ISSN Exercise & Sport Nutrition Review Research E Recommendations [TRIBULUS TERRESTRIS]...

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Sports Nutrition Review Journal. 1 (1):1-44, 2004. ( www.sportsnutritionsociety.org ) 3

adequate evidence to show that they are notfalse or misleading. Because of this, DSHEArequires supplement manufacturers to includeon the label that This statement has not beenevaluated by the FDA. This product is notintended to diagnose, treat, cure, or preventany disease". According to the 1994

Nutrition Labeling and Education Act(NELA), the FDA has the ability to reviewand approve health claims for dietarysupplements and foods. However, since thelaw was passed, it has only reviewed a fewclaims. The delay in reviewing health claimsof dietary supplements resulted in a law suitfiled by Pearson & Shaw et al v. Shalala et alin 1993. After years of litigation, U.S. Courtof Appeals for the District of ColumbiaCircuit ruled in 1999 that qualified healthclaims may now be made about dietary

supplements with approval by FDA as long asthe statements are truthful and based onscience. Supplement companies wishing tomake health claims about supplements cansubmit research evidence to the FDA forapproval. Additionally, they must submit anInvestigation of New Drug (IND) applicationto FDA if a research study on a nutrient isdesigned to treat an illness and/or medicalaffliction and/or the company hopes to oneday obtain approval for making a qualifiedhealth claim if the outcome of the studysupports the claim. Studies investigatingstructure and function claims, however, donot need to be submitted to the FDA as anIND.

Manufacturers and distributors of dietarysupplements are not currently required torecord, investigate or forward to FDA anyreports they receive on injuries or illnessesthat may be related to the use of their

products. However, the FDA and other groups

trends and signals that may suggest a problem. Once a dietary supplement productis marketed, the FDA has the responsibilityfor showing that a dietary supplement isunsafe before it can take action to restrict the

product's use or removal from themarketplace. The Federal Trade Commission(FTC) is responsible to make suremanufacturers are truthful regarding claimsthey make about dietary supplements. TheFDA has the power to remove supplementsfrom the market if it has sufficient scientificevidence to show the supplement is unsafe.Additionally, the FTC has the power to actagainst companies who make false and/ormisleading marketing claims about a specific

product. This includes acting againstcompanies if the ingredients found in thesupplement do not match label claims. While

this does not ensure the safety of dietarysupplements, it does provide a means forgovernmental oversight of the dietarysupplement industry if adequate resources are

provided to enforce DSHEA. Since inceptionof DSHEA, the FDA has required a numberof supplement companies to submit evidenceshowing safety of their products and acted toremove a number of products sold as dietarysupplements from sale in the U.S. due tosafety concerns. Additionally, the FTC hasacted against a number of supplementcompanies for misleading advertisementsand/or structure and function claims.

As can be seen, although some argue that thedietary supplement industry is unregulatedand/or may have suggestions for additionalregulation, manufacturers of dietarysupplements must adhere to a number offederal regulations before a product can go tomarket. Further, they must have evidence thatthe ingredients sold in their supplements are


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development, conduct preliminary research on products, and/or assist in coordinatingresearch trials conducted by independentresearch teams (e.g., university basedresearchers or clinical research sites). Theyalso consult with marketing teams with theresponsibility to ensure structure and functionclaims do not misrepresent results of researchfindings. This has increased job opportunitiesfor sport nutrition specialists as well asenhanced opportunities for external fundingfor research groups interested in exercisenutrition research. While it is true that somecompanies use borrowed science, suppressnegative findings, and/or exaggerate resultsfrom research studies, the trend in thenutrition industry is to develop scientificallysound supplements. This trend toward greaterresearch support is the result of: 1.) attempts

to honestly and accurately inform the publicabout results; 2.) efforts to have data tosupport safety and efficacy on products forFDA and the FTC; and/or, 3.) to providescientific evidence to support advertisingclaims and increase sales. This trend is duein large part to greater scrutiny from the FDAand FTC as a result of increased consumerexpectations and political pressure to ensurethat companies sell quality products that have

been shown to be safe and effective in clinicaltrials. In our experience, companies whoadhere to these ethical standards prosperwhile those who do not struggle to adhere toFDA and FTC guidelines and lose consumerconfidence. When this occurs, companies areoften sued by consumers and/or are forced outof business because ultimately the consumerhas the final word on whether a supplement orsupplement company is credible or not.

HOW TO EVALUATE NUTRITIONALERGOGENIC AIDS

and determining whether there is any well-controlled data showing thesupplement/technique works. Trainingdevices and supplements based on soundscientific rationale with supportive researchshowing effectiveness may be worth tryingand/or recommending. However, those basedon unsound scientific rationales and/or littleto no data supporting the ergogenic value for

people involved in intense training may not.The sport nutrition specialist should be aresource to help their clients interpret thescientific and medical research that mayimpact on their welfare and/or help them trainmore wisely. The following are the questionswe recommend asking when evaluating the

potential ergogenic value of a supplement.

Does Th e Theory M ake Sense?

Most supplements that have been marketed toimprove health and/or exercise performanceare based on theoretical applications derivedfrom basic and/or clinical research studies.Based on these preliminary studies, a trainingdevice or supplement is often marketed to

people proclaiming the benefits observed in

these basic research studies. Although thetheory may sound good, critical analysis ofthe theory often reveals flaws in scientificlogic and/or that the claims made dont quitematch up with the literature cited. If you doyour homework, you can discern whether asupplement has been based on soundscientific evidence or not. To do so, we

suggest you read reviews about the trainingmethod, nutrient, and/or supplement fromresearchers who have been intimatelyinvolved in this line of research and/or consultreliable references about nutritional andherbal supplements 4-8. We also suggestdoing a search on the nutrient/supplement on


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are either unaware and/or ignorant of researchsupporting their use. The sport nutritionspecialist has the responsibility to know theliterature and/or search available data bases toknow whether there is merit or not to a

proposed ergogenic aid.

I s Th ere An y Scientif ic Evidence Supporti ngThe Er gogenic Value?

The next question suggest asking is whetherthere is any well-controlled data showing the

proposed ergogenic aid works as claimed inathletes or people involved in training. Thefirst place we look is the list of referencescited in marketing material supporting theirclaims. We look to see if the abstracts orarticles cited are general references or specificstudies that have evaluated the efficacy of the

nutrient/supplement. We then criticallyevaluate the abstracts and articles by asking aseries of questions.

Are the studies simply basic research donein animals/clinical populations or have thestudies been conducted on athletes?Studies reporting improved performance

in rats may be insightful but researchconducted on athletes is much moreconvincing.

Were the studies well controlled? Forergogenic aid research, the study should

be a placebo controlled, double blind, andrandomized clinical trail if possible. Thismeans that neither the researchers nor thesubjects were aware which groupreceived the supplement or the placeboduring the study and that the subjects wererandomly assigned into the placebo orsupplement group. At times, supplementclaims have been based on poorlydesigned studies (i.e., small groups of

Do the studies report statisticallysignificant results or are claims beingmade on non-significant means or trendsreported? Appropriate statistical analysisof research results allows for an unbiasedinterpretation of data. Although studiesreporting statistical trends may be ofinterest and lead researchers to conductadditional research, studies reportingstatistically significant results areobviously more convincing. With this

said, sport nutrition specialist must becareful not to commit type II statisticalerror (i.e., indicating that no differenceswere observed when a true effect was seen

but not detected statistically). Since manystudies on ergogenic aids (particularly inhigh level athletes) evaluate smallnumbers of subjects, results may not reach

statistical significance even though largemean changes were observed. In thesecases, additional research is warranted tofurther examine the potential ergogenicaid before conclusions can be made.

Do the results of the studies cited matchthe claims made about the supplement?It is not unusual for marketing claims togreatly exaggerate the results found in theactual studies. Therefore, you shouldcompare results observed in the studies tomarketing claims. Reputable companiesaccurately report results of studies so thatconsumers can make informed decisionsabout whether to try a product or not.

Were results of the study presented at areputable scientific meeting and/or

published in a peer-reviewed scientific journal? At times, claims are based onresearch that has either never been

published or only published in an obscure journal. The best research is typically presented at respected scientific meetings


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aids are those in which a number ofstudies, conducted at different labs, havereported similar results.

I s The Supplement L egal A nd Safe?

The final question we ask is whether thesupplement is legal and/or safe. Someathletic associations have banned the use ofvarious nutritional supplements (e.g.,

prohormones, ephedra, etc). Obviously, if the

supplement is banned, the sport nutritionspecialist should discourage its use. Inaddition, many supplements have not beenstudied for long-term safety. People whoconsider taking nutritional supplementsshould be well aware of the potential sideeffects so that they can make an informeddecision regarding whether to use a

supplement or not. Additionally, they shouldconsult with a knowledgeable physician to seeif there are any underlying medical problemsthat may contraindicate use. When evaluatingthe safety of a supplement, we suggestlooking to see if any side effects have beenreported in the scientific or medical literature.In particular, we suggest determining howlong a particular supplement has been studied,the dosages evaluated, and whether any sideeffects were observed. We also recommendconsulting the PDR for nutritionalsupplements and herbal supplements to see ifany side effects have been reported and/orthere are any known drug interactions. If noside effects have been reported in thescientific/medical literature, we generally willview the supplement as safe for the length oftime and dosages evaluated.

CLASSIFYING AND CATEGORIZINGSUPPLEMENTS

and/or managing caloric intake, weight gainsupplements, weight loss supplements, and

performance enhancement supplements.Based on the above criteria, we generallycategorize nutritional supplements into thefollowing categories:

I. Apparently Effective. Supplements thathelp people meet general caloric needsand/or the majority of research studiesshow is effective and safe.

II. Possibly Effective. Supplements thatinitial studies support the theoreticalrationale but that more research is neededto determine how the supplement mayaffect training and/or performance.

III. Too Early To Tell. Supplements that thetheory may make sense but there isinsufficient research to support the use at

this time.IV. Apparently Ineffective. Supplementsthat the theoretical rationale makes littlescientific sense and/or research has clearlyshown to be ineffective.

When a sport nutrition specialist councils people who train, they should first evaluatetheir diet and training program. They shouldmake sure that the athlete is eating an energy

balanced, nutrient dense diet and that they aretraining intelligently. This is the foundationto build a good program. Following this, werecommend that they generally onlyrecommend supplements in category I. Ifsomeone is interested in trying supplements incategory II, they should make sure that theyunderstand that these supplements are moreexperimental and that they may or may notsee the type of results claimed. Werecommend discouraging people from tryingsupplements in category III because thereisnt enough data available on whether they


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balanced view than simply dismissing the useof all dietary supplements out of hand.

GENERAL DIETARY GUIDELINESFOR ACTIVE INDIVIDUALS

A well-designed diet that meets energy intakeneeds and incorporates proper timing ofnutrients is the foundation upon which a goodtraining program can be developed. Research

has clearly shown that athletes that do notingest enough calories and/or do not consumeenough of the right type of macronutrientsmay impede training adaptations whileathletes who consume a good diet can helpthe body adapt to training. Moreover,maintaining an energy deficient diet duringtraining may lead to loss of muscle mass,

increased susceptibility to illness, andincrease prevalence of overreaching and/orovertraining. Incorporating good dietary

practices as part of a training program is oneway to help optimize training adaptations and

prevent overtraining. The followingoverviews energy intake and major nutrientneeds of active individuals.

Energy I ntake

The first component to optimize training and performance through nutrition is to ensure theathlete is consuming enough calories to offsetenergy expenditure 1, 10-12 . People who

participate in a general fitness program (e.g.,exercising 30 - 40 minutes per day, 3 times

per week) can generally meet nutritionalneeds following a normal diet (e.g., 1,800 2,400 kcals/day or about 25 - 35 kcals/kg/dayfor a 50 80 kg individual) because theircaloric demands from exercise are not toogreat (e.g., 200 400 kcals/session) 1.

needs may approach 50 80 kcals/kg/day(2,500 8,000 kcals/day for a 50 100 kgathlete). For elite athletes, energyexpenditure during heavy training orcompetition may be enormous. For example,energy expenditure for cyclists to compete inthe Tour de France has been estimated as highas 12,000 kcals/day (150 - 200 kcals/kg/d fora 60 80 kg athlete) 13-15 . Additionally,caloric needs for large athletes (i.e., 100 150kg) may range between 6,000 12,000

kcals/day depending on the volume andintensity of different training phases 13.

Although some argue that athletes can meetcaloric needs simply by consuming a well-

balanced diet, it is often very difficult forlarger athletes and/or athletes engaged in highvolume/intense training to be able to eat

enough food in order to meet caloric needs1,

11, 13-15 . Maintaining an energy deficient dietduring training often leads to significantweight loss (including muscle mass), illness,onset of physical and psychologicalsymptoms of overtraining, and reductions in

performance 12. Nutritional analyses ofathletes diets have revealed that many aresusceptible to maintaining negative energyintakes during training. Susceptible

populations include runners, cyclists,swimmers, triathletes, gymnasts, skaters,dancers, wrestlers, boxers, and athletesattempting to lose weight too quickly 11 .Additionally, female athletes have beenreported to have a high incidence of eatingdisorders 11 . Consequently, it is important forthe sport nutrition specialist working withathletes to ensure that athletes are well-fedand consume enough calories to offset theincreased energy demands of training andmaintain body weight. Although this soundsrelatively simple, intense training often


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food choices and how to how to count fatgrams 1, 11 .

Strategic Eating and Refu eli ng

In addition to the general nutritionalguidelines described above, research has alsodemonstrated that timing and composition ofmeals consumed may play a role inoptimizing performance, training adaptations,and preventing overtraining 1, 10, 36, 37 . In this

regard, it takes about 4 hours for carbohydrateto be digested and begin to be stored asmuscle and liver glycogen. Consequently,

pre-exercise meals should be consumed about4 to 6 h before exercise 10. This means that ifan athlete trains in the afternoon, breakfast isthe most important meal to top off muscle andliver glycogen levels. Research has also

indicated that ingesting a light carbohydrateand protein snack 30 to 60 min prior toexercise (e.g., 50 g of carbohydrate and 5 to10 g of protein) serves to increasecarbohydrate availability toward the end of anintense exercise bout 38, 39 . This also serves toincrease availability of amino acids anddecrease exercise-induced catabolism of

protein 36, 38, 39 .

When exercise lasts more than one hour,athletes should ingest glucose/electrolytesolution (GES) drinks in order to maintain

blood glucose levels, help preventdehydration, and reduce theimmunosuppressive effects of intenseexercise 10, 40-45 . Following intenseexercise, athletes should consumecarbohydrate and protein (e.g., 1 g/kg ofcarbohydrate and 0.5 g/kg of protein) within30 min after exercise as well as consume ahigh carbohydrate meal within two hoursfollowing exercise 1, 36, 37 . This nutritional

has been shown to supersaturatecarbohydrate stores prior to competition andimprove endurance exercise capacity 1, 10, 37 .Thus, the type of meal and timing of eatingare important factors in maintainingcarbohydrate availability during trainingand potentially decreasing the incidence ofovertraining.

Vitamins

Vitamins are essential organic compoundswhich serve to regulate metabolic processes,energy synthesis, neurological processes, and

prevent destruction of cells. There are two primary classifications of vitamins: fat andwater soluble. The fat soluble vitaminsinclude vitamins A, D, E, & K. The bodystores fat soluble vitamins and therefore

excessive intake may result in toxicity. Watersoluble vitamins are B vitamins and vitaminC. Since these vitamins are water soluble,excessive intake of these vitamins areeliminated in urine. Table 1 describes RDA,

proposed ergogenic benefit, and summary ofresearch findings for fat and water solublevitamins. Although research hasdemonstrated that specific vitamins may

posses some health benefit (e.g., vitamin E,niacin, folic acid, vitamin C, etc), few have

been reported to directly provide ergogenicvalue for athletes. However, some vitaminsmay help athletes tolerate training to a betterdegree by reducing oxidative damage(vitamin E, C) and/or help to maintain ahealthy immune system during heavy training(vitamin C). Theoretically, this may helpathletes tolerate heavy training leading toimproved performance. The remainingvitamins reviewed appear to have littleergogenic value for athletes who consume anormal, nutrient dense diet. Since dietary


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the available medical literature andrecommended that Americans consume a one-a-day low-dose multivitamin in order to

promote general health. Suggestions thatthere is no benefit of vitamin supplementationfor athletes and/or it is unethical for an sportnutrition specialist to recommend that theirclients take a one-a-day multi-vitamin and/orsuggest taking other vitamins that may reducecholesterol levels (niacin), serve asantioxidants (Vitamin E), decrease risk to

heart disease (niacin, Vitamin E), or may helpmaintain a health immune system (Vitamin C)is not consistent with current availableliterature.

Minerals

Minerals are essential inorganic elements

necessary for a host of metabolic processes.Minerals serve as structure for tissue,important components of enzymes andhormones, and regulators of metabolic andneural control. Some minerals have beenfound to be deficient in athletes or becomedeficient in response to training and/or

prolonged exercise. When mineral status isinadequate, exercise capacity may be reduced.Dietary supplementation of minerals indeficient athletes has generally been found toimprove exercise capacity. Additionally,supplementation of specific minerals in non-deficient athletes has also been reported toaffect exercise capacity. Table 2 describesminerals that have been purported to affectexercise capacity in athletes. Of the mineralsreviewed, several appear to possess healthand/or ergogenic value for athletes undercertain conditions. For example, calciumsupplementation in athletes susceptible to

premature osteoporosis may help maintain bone mass. There is also recent evidence that

availability of salt (sodium chloride) duringthe initial days of exercise training in the heathas been reported to help maintain fluid

balance and prevent dehydration. Finally,zinc supplementation during training has beenreported to decrease exercise-induced changesin immune function. Consequently,somewhat in contrast to vitamins, thereappear to be several minerals that mayenhance exercise capacity and/or trainingadaptations for athletes under certain

conditions. However, although ergogenicvalue has been purported for remainingminerals, there is little evidence that boron,chromium, magnesium, or vanadium affectexercise capacity or training adaptations inhealthy individuals eating a normal diet.Suggestions that there is no benefit of mineralsupplementation for athletes and/or it is

unethical for an sport nutrition specialist torecommend that their clients take mineralsthat research has shown may affect healthand/or performance is not consistent withcurrent available literature.

Water

The most important nutritional ergogenic aidfor athletes is water. Exercise performancecan be significantly impaired when 2% ormore of body weight is lost through sweat.For example, when a 70-kg athlete loses morethan 1.4 kg of body weight during exercise(2%), performance capacity is oftensignificantly decreased. Further, weight lossof more than 4% of body weight duringexercise may lead to heat illness, heatexhaustion, heat stroke, and possibly death 45.For this reason, it is critical that athletesconsume a sufficient amount of water and/orGES sports drinks during exercise in order tomaintain hydration status. The normal sweat


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cold water or a GES sports drink every 5 to15-min during exercise 45, 49-52 . Athletes andshould not depend on thirst to prompt them todrink because people do not typically getthirsty until they have lost a significantamount of fluid through sweat. Additionally,athletes should weigh themselves prior to andfollowing exercise training to ensure that theymaintain proper hydration 45, 49-52 . The athleteshould consume 3 cups of water for every

pound lost during exercise in order adequately

rehydrate themselves45

. Athletes should trainthemselves to tolerate drinking greateramounts of water during training and makesure that they consume more fluid inhotter/humid environments. Preventingdehydration during exercise is one of the mosteffective ways to maintain exercise capacity.Finally, inappropriate and excessive weight

loss techniques (e.g., cutting weight in saunas,wearing rubber suits, severe dieting, vomiting,using diuretics, etc) are extremely dangerousand should be prohibited. Sport nutritionspecialists can play an important role ineducating athletes and coaches about properhydration methods and supervising fluidintake during training and competition.

DIETARY SUPPLEMENTS ANDATHLETES

Most of the work we do with athletesregarding sport nutrition is to teach them andtheir coaches how to structure their diet andtime food intake to optimize performance andrecovery. Dietary supplements can play ameaningful role in helping athletes consumethe proper amount of calories, carbohydrate,and protein in their diet. However, theyshould be viewed as supplements to the diet,not replacements for a good diet. While it istrue that most dietary supplements available

specialists must be aware of the current dataregarding nutrition, exercise, and performanceand be honest about educating their clientsabout results of various studies (whether proor con). With the proliferation of informationavailable about nutritional supplements to theconsumer, the sport nutrition specialist,nutritionist, and nutrition industry losecredibility when they do not accuratelydescribe results of various studies to the

public. The following overviews several

classifications of nutritional supplements thatare often taken by athletes and categorizesthem into apparently effective, possiblyeffective, too early to tell, and apparentlyineffective supplements based on myinterpretation of the literature. It should benoted that this analysis will primarily focuson whether the proposed nutrient has been

found to affect exercise and/or trainingadaptations based on the current availableliterature. Additional research may reveal itmay or may not possess ergogenic valuewhich may then change its classification. Itshould be also noted that although there may

be little ergogenic value to some nutrients,there may be some potential health benefitsthat may be helpful for some populations.Therefore, just because a nutrient does notappear to affect performance and/or trainingadaptations, that does not mean it may nothave possible health benefits.

Convenience Suppl ements

Convenience supplements are mealreplacement powders (MRPs), ready to drinksupplements (RTDs), energy bars, andenergy gels. They currently represent thelargest segment of nutrition industryrepresenting 50 75% of most companyssales. They are typically fortified with 33


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snacks and/or use them to help control caloricintake when trying to gain and/or lose weight.In our view, MRPs, RTDs, and energy

bars/gels can provide a convenient way for people to meet specific dietary needs and/orserve as good alternatives to fast food. Use ofthese types of products can be particularlyhelpful in providing carbohydrate, protein,and other nutrients prior to and/or followingexercise in an attempt to optimize nutrientintake when an athlete doesnt have time to sit

down for a good meal. However, they should be used to improve dietary availability ofmacronutrients not as a replacement for agood diet. Care should also be taken to makesure they do not contain any banned or

prohibited nutrients.

M uscle Bu il ding Supplements

The following provides an analysis of theliterature regarding purported weight gainsupplements and our general interpretation ofhow they should be categorized based on thisinformation. Table 3 summarizes how wecurrently classify the ergogenic value of anumber of purported performance-enhancing,muscle building, and fat loss supplements

based on an analysis of the available scientificevidence.

Apparently Effective

Weight Gain Powders . One of the mostcommon means athletes have employed toincrease muscle mass is to add extra caloriesto the diet. Most athletes bulk up in thismanner by consuming extra food and/orweight gain powders. Studies haveconsistently shown that simply adding anextra 500 1,000 calories per day to your dietwill promote weight gain 20, 36 However

Therefore, we typically do not recommendthis type of weight gain approach.

Creatine. In our view, the most effectivenutritional supplement available to athletes toincrease high intensity exercise capacity andmuscle mass during training is creatine.

Numerous studies have indicated that creatinesupplementation increases body mass and/ormuscle mass during training 53 Gains aretypically 2 5 pounds greater than controls

during 4 12 weeks of training54

. The gainsin muscle mass appear to be a result of animproved ability to perform high intensityexercise enabling an athlete to train harderand thereby promote greater trainingadaptations and muscle hypertrophy 55-57 . Theonly clinically significant side effect reportedfrom creatine supplementation has been

weight gain36, 53, 54, 58

Although concernshave been raised about the safety and possibleside effects of creatine supplementation 59, 60 ,recent long-term safety studies have reportedno apparent side effects 58, 61, 62 and/or thatcreatine may lessen the incidence of injuryduring training 63-65 . Consequently,supplementing the diet with creatine and/orcreatine containing formulations seems to bea safe and effective method to increasemuscle mass.

-hydroxy -methylbutyrate (H M B). HMBis a metabolite of the amino acid leucine.Leucine and metabolites of leucine have beenreported to inhibit protein degradation 66.Supplementing the diet with 1.5 to 3 g/d ofcalcium HMB has been typically reported toincrease muscle mass and strength

particularly among untrained subjectsinitiating training 67-72 and the elderly 73.Gains in muscle mass are typically 0.5 to 1 kggreater than controls during 3 6 weeks of


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mass possibly due to a greater variability inresponse of HMB supplementation amongathletes 77-79 . Consequently, there is fairlygood evidence showing that HMB mayenhance training adaptations in individualsinitiating training. However, additionalresearch is necessary to determine whetherHMB may enhance training adaptations inathletes.

Possibly Effective

Br anched Chain A mino A cids (BCAA ).BCAA supplementation has been reported todecrease exercise-induced protein degradationand/or muscle enzyme release (an indicator ofmuscle damage) possibly by promoting ananti-catabolic hormonal profile 36, 38, 80 .Theoretically, BCAA supplementation during

intense training may help minimize proteindegradation and thereby lead to greater gainsin fat-free mass. There is some evidence tosupport this hypothesis. For example, Schenaand colleagues 81 reported that BCAAsupplementation (~10 g/d) during 21-days oftrekking at altitude increased fat free mass(1.5%) while subjects ingesting a placebo hadno change in muscle mass. Bigard andassociates 82 reported that BCAAsupplementation appeared to minimize loss ofmuscle mass in subjects training at altitude for6-weeks. Finally, Candeloro and coworkers83 reported that 30 days of BCAAsupplementation (14 grams/day) promoted asignificant increase in muscle mass (1.3%)and grip strength (+8.1%) in untrained

subjects. Although more research isnecessary, these findings suggest that BCAAsupplementation may have some impact on

body composition.

Essenti al Ami no Acids (EA A). Recent

resistance exercise promoted significantlygreater training adaptations as compared towaiting until 2-hours after exercise toconsume the supplement. Although moredata is needed, there appears to be strongtheoretical rationale and some supportiveevidence that EAA supplementation mayenhance protein synthesis and trainingadaptations.

Glutamine. Glutamine is the most plentiful

non-essential amino acid in the body and plays a number of important physiologicalroles 36. Glutamine has been reported toincrease cell volume and stimulate protein 94-96 and glycogen synthesis 97. Theoretically,glutamine supplementation prior to and/orfollowing exercise (e.g., 6-10 g) may help tooptimize cell hydration and protein synthesis

during training leading to greater gains inmuscle mass and strength 36, 98 . In support ofthis hypothesis, a recent study by Colker andassociates 99 found that subjects whosupplemented their diet with glutamine (5grams) and BCAA (3 grams) enriched whey

protein during training promoted about a 2 pound greater gain in muscle mass and greatergains in strength than ingesting whey proteinalone. Although more data is needed, thereappears to be a strong scientific rationale andsome preliminary evidence to indicate thatglutamine may help build muscle.

Protein. As previously described, researchhas indicated that people undergoing intensetraining may need additional protein in their

diet to meet protein needs (i.e., 1.5 2.0grams/day). People who do not ingest enough

protein in their diet may slow recovery andtraining adaptations 36. Protein supplementsoffer a convenient way to ensure that athletesconsume quality protein in the diet and meet


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biologically active protein subtypes and peptides (e.g., -lactalbumin, -lactoglobulin,glycomacropeptides, immunoglobulins,lactoperoxidases, lactoferrin, etc) havevarying effects on the physiological,hormonal, and/or immunological responses totraining. In addition, whether timing of

protein intake may play a role in proteinsynthesis and training adaptations 85-92 .Although more research is necessary in thisarea, research clearly indicates that protein

needs of individuals engaged in intensetraining are elevated, that different types of protein have varying effects on anabolism andcatabolism, that different types of proteinsubtypes and peptides have unique

physiological effects, and that timing of protein intake may play an important role inoptimizing protein synthesis following

exercise. Therefore, it is simplistic andmisleading to suggest that there is no datasupporting contentions that athletes needmore protein in their diet and/or there is no

potential ergogenic value of incorporatingdifferent types of protein into the diet.

Too Early to Tell

-ketoglu tarate ( -KG). -KG is anintermediate in the Krebs cycle that isinvolved in aerobic energy metabolism.There is some clinical evidence that -KGmay serve as an anticatabolic nutrient aftersurgery 100, 101 . However, it is unclearwhether -KG supplementation duringtraining may affect training adaptations.

-Ketoisocaproate (KI C). KIC is a branched-chain keto acid that is a metabolite of leucinemetabolism. In a similar manner as HMB,leucine and metabolites of leucine arebelieved to possess anticatabolic properties

composition.

Ecdysterones. Ecdysterones (also known asectysterone, 20 Beta-Hydroxyecdysterone,turkesterone, ponasterone, ecdysone, orecdystene) are naturally derived

phytoecdysteroids (i.e., insect hormones).They are typically extracted from the herbsLeuza rhaptonticum sp., Rhaponticumcarthamoides, or Cyanotis vaga. They canalso be found in high concentrations in the

herb Suma (also known as Brazilian Ginsengor Pfaffia). Research from Russia andCzechoslovakia conducted over the last 30years indicates that ecdysterones may possesssome potentially beneficial physiologicaleffects in insects and animals 105-109 .However, since most of the data onecdysterones have been published in obscure

journals, results are difficult to interpret.While future studies may find some ergogenicvalue of ecdysterones, it is our view that it istoo early to tell whether phytoecdysteroidsserve as a safe and effective nutritionalsupplement for athletes.

Growth H ormon e Releasin g Peptides(GH RP) and Secretogues. Research hasindicated that growth hormone releasing

peptides (GHRP) and other non-peptidecompounds (secretagogues) appear to helpregulate growth hormone (GH) release 110, 111 .These observations have served as the basisfor development of nutritionally-based GHstimulators (e.g., amino acids, pituitary

peptides, pituitary substances, macuna

pruriens, broad bean, alpha GPC, etc).Although there is clinical evidence that

pharmaceutical grade GHRPs and some non- peptide secretagogues can increase GH andIGF-1 levels at rest and in response toexercise, it is currently unknown whether any


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the treatment of osteoporosis) 112-114 . For thisreason, soy protein (which is an excellentsource of isoflavones) and isoflavone extractshave been investigated in the possibletreatment of osteoporosis. Results of thesestudies have shown promise in preventingdeclines in bone mass in post-menopausalwomen as well as reducing risks to sideeffects associated with estrogen replacementtherapy. More recently, the isoflavoneextracts 7-isopropoxyisoflavone (ipriflavone)

and 5-methyl-7-methoxy-isoflavone(methoxyisoflavone) have been marketed aspowerful anabolic substances. These claimshave been based on research described in

patents filed in Hungary in the early 1970s 115,116 . Although the data presented in the patentsare interesting, there is currently no peer-reviewed data indicating that isoflavonesupplementation affects exercise, bodycomposition, or training adaptations.

Ornithine- -ketoglu tarate (OKG). OKG isanother nutrient believed to possessanabolic/catabolic effect. Animal and clinicalstudies have suggested that patientsadministered OKG experienced improved

protein balance 115, 116 . Theoretically, OKGmay provide some value for athletes engagedin intense training. A recent study by Chetlinand colleagues 117 reported that OKGsupplementation (10 grams/day) during 6-weeks of resistance training promoted greatergains in bench press. However, no significantdifferences were observed in squat strength,training volume, gains in muscle mass, orfasting insulin and growth hormone.Therefore, additional research is needed

before conclusions can be drawn.

Sul fo-Polysacchar ides (M yostatinInhibitors) Myostatin or growth

and development. The result is that theseanimals experience what has been termed as adouble-muscle phenomenon apparently byallowing muscle to grow beyond its normalgenetic limit. In agriculture research,eliminating and/or inhibiting myostatin mayserve as an effective way to optimize animalgrowth leading to larger, leaner, and a more

profitable livestock yield. In humans,inhibiting myostatin gene expression has beentheorized as a way to prevent or slow down

muscle wasting in various diseases, speed uprecovery of injured muscles, and/or promoteincreases in muscle mass and strength inathletes 123 . While these theoretical

possibilities may have great promise, researchon the role of myostatin inhibition on musclegrowth and repair is in the very early stages

particularly in humans. There is someevidence that myostatin levels are higher inthe blood of HIV positive patients who haveexperience muscle wasting and that myostatinlevels negatively correlate with musclemass 118 . There is also evidence thatmyostatin gene expression may be fiberspecific and that myostatin levels may beinfluenced by immobilization in animals 124 .Additionally, a recent study by Ivey andcolleagues 123 reported that female athleteswith a less common myostatin allele (agenetic subtype that may be more resistant tomyostatin) experienced greater gains inmuscle mass during training and less loss ofmuscle mass during detraining. No such

pattern was observed in men with varyingamounts of training histories and muscle

mass. These early studies suggest thatmyostatin may play a role in regulatingmuscle growth to some degree. Recently,some nutrition supplement companies havemarketed sulfo-polysaccharides (derived froma sea algae called Cytoseira canariensis) as a


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Smilax Off icinal is (SO). SO is a compoundwhich contains plant sterols purported toenhance immunity as well as provide anandrogenic effect on muscle growth 1. Somedata supports the potential immune enhancingeffects of SO. However, we are not aware ofany data that show that SO supplementationincreases muscle mass during training.

Zin c/Magnesium Aspartate (ZM A). ZMAformulations have recently become a popular

supplement purported to promote anabolismat night. The theory is based on studiessuggesting that zinc and magnesiumdeficiency may reduce the production oftestosterone and insulin like growth factor(IGF-1). ZMA supplementation has beentheorized to increase testosterone and IGF-1leading to greater recovery, anabolism, andstrength during training. In support of thistheory, Brilla and Conte 125 reported that azinc-magnesium formulation increasedtestosterone and IGF-1 (two anabolichormones) leading to greater gains in strengthin football players participating in springtraining. While these data are interesting,more research is needed to further evaluatethe role of ZMA on body composition andstrength during training before conclusionscan be drawn.

Apparently Ineffective

Boron. Boron is a trace mineral proposed toincrease testosterone levels and promoteanabolism. Several studies have evaluated the

effects of boron supplementation duringtraining on strength and body compositionalterations. These studies indicate that boronsupplement (2.5 mg/d) appears to have noimpact on muscle mass or strength 126, 127 .

theorized to serve as an anabolic nutrient.Theoretically, this may increase anabolicresponses to exercise. Although some initialstudies reported that chromiumsupplementation increased gains in musclemass and strength during training particularlyin women 128-130 , most well-controlled thathave been conducted since then have reportedno benefit in healthy individuals takingchromium (200-800 mcg/d) for 4 to 16-weeksduring training 131-137 . Consequently, it

appears that although chromiumsupplementation may have some therapeutic benefits for diabetics, chromium does notappear to be a muscle-building nutrient forathletes.

Conjugated L inoleic A cids (CLA ). Animalstudies indicate that adding CLA to dietaryfeed decreases body fat, increases muscle and

bone mass, has anti-cancer properties,enhances immunity, and inhibits progressionof heart disease 138-140 . Consequently, CLAsupplementation in humans has beensuggested to help manage body composition,delay loss of bone, and provide health benefit.Although animal studies are impressive 141-143 and a some studies suggests benefit at some

but not all dosages 144, 145 , most studiesconducted on humans show little to no effecton body composition or muscle growth. 146, 147

Gamma Oryzanol (F eru li c Acid). Gammaoryzanol is a plant sterol theorized to increaseanabolic hormonal responses during training148. Although data are limited, one study

reported no effect of 0.5 g/d of gammaoryzanol supplementation on strength, musclemass, or anabolic hormonal profiles during 9-weeks of training 149 .

Anabolic Steroids & Proh ormon es.


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prescribed by physicians to prevent loss ofmuscle mass for people with various diseasesand illnesses 155-166 . It is well known that

athletes have experimented with large dosesof anabolic steroids in an attempt to enhancetraining adaptations, increase muscle mass,and/or promote recovery during intensetraining 150-154 . Research has generally shownthat use of anabolic steroids and growthhormone during training can promote gains instrength and muscle mass 150, 160, 167-174 .

However, a number of potentially lifethreatening adverse effects of steroid abusehave been reported including liver andhormonal dysfunction, hyperlipidemia (highcholesterol), increased risk to cardiovasculardisease, and behavioral changes (i.e., steroidrage) 169, 175-179 . Some of the adverse effectsassociated with the use of these agents areirreversible, particularly in women 176 . Forthis reason, anabolic steroids have has been

banned by most sport organizations andshould be avoided unless prescribed by a

physician to treat an illness.

Prohormones (androstenedione, 4-androstenediol, 19-nor-4-androstenedione,19-nor-4-androstenediol, 7-keto DHEA, andDHEA, etc) are naturally derived precursorsto testosterone or other anabolic steroids.Prohormones have become popular among

body builders because they believe they arenatural boosters of anabolic hormones.Consequently, a number of over-the-countersupplements contain prohormones. Whilethere is a strong theoretical rationale that

prohormones may increase testosteronelevels, there is virtually no evidence that thesecompounds affect training adaptations inyounger men with normal hormone levels. Infact, most studies indicate that they do notaffect testosterone and that some may actually

nutritional supplements containing prohormones will result in a positive drug testfor anabolic steroids. Use of supplements

knowingly or unknowingly containing prohormones have been believed to havecontributed to a number of recent positivedrug tests among athletes. Consequently, careshould be taken to make sure that anysupplement an athlete considers taking doesnot contain prohormone precursors

particularly if their sport bans and tests for

use of such compounds.

Tr ibulu s Terr estri s. Tribulus terrestris (alsoknown as puncture weed/vine or caltrops) is a

plant extract that has been suggested tostimulate leutinizing hormone (LH) whichstimulates the natural production oftestosterone 102 . Consequently, Tribulus has

been marketed as a supplement that canincrease testosterone and promote greatergains in strength and muscle mass duringtraining. Several recent studies haveindicated that Tribulus supplementationappears to have no effects on bodycomposition or strength during training 187, 188 .

Vanadyl Sul fate (Vanadium). In a similarmanner as chromium, vanadyl sulfate is atrace mineral that has been found to affectinsulin-sensitivity and may affect protein andglucose metabolism 102 . For this reason,vanadyl sulfate has been purported to increasemuscle mass and strength during training.Although there may be some clinical benefitsfor diabetics, vanadyl sulfate supplementation

does not appear to have any effect on strengthor muscle mass during training in non-diabetic individuals 189, 190 .

Weight L oss Supplements


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research supports their use. See Table 3 for asummary.


L ow Calori e Di et Foods & Supplements. Most of the products in this categoryrepresent low fat/carbohydrate, high proteinfood alternatives 191 . They typically consistof pre-packaged food, bars, MRP, or RTDsupplements. They are designed to provideconvenient foods/snacks to help people followa particular low calorie diet plan. In thescientific literature, diets that provide lessthan 1000 calories per day are known as verylow calorie diets (VLCDs). Pre-packagedfood, MRPs, and/or RTDs are often

provided in VLCD plans to help people cutcalories. In most cases, VLCD plans

recommend behavioral modification and that people start a general exercise program.

Research on the safety and efficacy of peoplemaintaining VLCDs generally indicate thatthey can promote weight loss. For example,Hoie et al 192 reported that maintaining aVLCD for 8-weeks promoted a 27 lbs

(12.6%) loss in total body mass, a 21 lbs lossin body fat (23.8%), and a 7 lbs (5.2%) loss inlean body mass in 127 overweight volunteers.Bryner and colleagues 193 reported thataddition of a resistance training programwhile maintaining a VLCD (800 kcal/d for12-weeks) resulted in a better preservation oflean body mass and resting metabolic ratecompared to subjects maintaining a VLCDwhile engaged in an endurance training

program. Kern and coworkers 194 reportedthat a medically supervised weight loss

program involving behavioral modificationand VLCD promoted a 51 lbs weight loss andthat 61% of subjects maintained at least 50%

Increasing protein intake during weight losshelps preserve muscle mass and restingenergy expenditure to a better degree than

high carbohydrate diets 199 . These findingsand others indicate that VLCDs (typicallyusing MRPs and/or RTDs as a means tocontrol caloric intake) can be effective

particularly as part of an exercise and behavioral modification program. Most people appear to maintain at least half of theinitial weight lost for 1-2 years but tend to

regain most of the weight back within 2-5years. Therefore, although these diets mayhelp people lose weight on the short-term, itis essential people who use them follow gooddiet and exercise practices in order tomaintain the weight loss.

Ephedra, Caff ein e, and Sil icin.Thermogenics are supplements designed tostimulate metabolism thereby increasingenergy expenditure and promote weight loss.They typically contain the ECA stack ofephedra alkaloids (e.g., Ma Haung, 1R,2S

Nor-ephedrine HCl, Sida Cordifolia), caffeine(e.g., Gaurana, Bissey Nut, Kola) andaspirin/salicin (e.g., Willow Bark Extract).More recently, other potentially thermogenicnutrients have been added to variousthermogenic formulations. For example,thermogenic supplements may also containsynephrine (e.g., Citrus Aurantum, BitterOrange), calcium & sodium phosphate,thyroid stimulators (e.g., guggulsterones, L-tyrosine, iodine), cayenne & black pepper,and ginger root.

A significant amount of research hasevaluated the safety and efficacy of EC andECA type supplements. Studies show thatuse of synthetic or herbal sources ofephedrine and caffeine (EC) promote about 2


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minor side effects. Molnar and associates 200 reported that overweight children treated for20 weeks with ephedrine and caffeine

observed a 14.4% loss in body mass and a6.6% decrease in body fat with no differencesin side effects. Interestingly, Greenway andcolleagues 208reported that ECsupplementation was a more cost-effectivetreatment for reducing weight, cardiac risk,and LDL cholesterol than several weight lossdrugs (fenfluramine with mazindol or

phentermine). Finally, Boozer and associates200 reported that 6-months of herbal ECsupplementation promoted weight loss withno clinically significant adverse effects inhealthy overweight adults. Less is knownabout the safety and efficacy of synephrine,thyroid stimulators, cayenne/black pepper andginger root.

Despite these findings, the Food and DrugAdministration (FDA) has recently bannedthe sale of ephedra containing supplements.The rationale has been based on reports toadverse event monitoring systems and in themedia suggesting a link between intake ofephedra and a number of severe medicalcomplications (e.g., high blood pressure,elevated heart rate, arrhythmias, suddendeath, heat stroke, etc) 210, 211 . Althoughresults of available clinical studies do notshow these types of adverse events and the

ban is in the process of being contestedlegally, ephedra is no longer available as aningredient in dietary supplements.Consequently, thermogenic supplements now

contain other nutrients believed to increaseenergy expenditure (e.g., synephrine, greentea, etc). Anyone contemplating takingthermogenic supplements should carefullyconsider the potential side effects, discuss

possible use with a knowledgeable physician,

foods (fruits, vegetables) or fiber supplementsincrease the feeling of fullness (satiety). Theytypically allow you to feel full while ingesting

fewer calories. Theoretically, maintaining ahigh fiber diet may serve to help decrease theamount of food you eat. In addition, highfiber diets/supplements have also been

purported to help lower cholesterol and blood pressure as well as help diabetics manageglucose and insulin levels. Some of theresearch conducted on high fiber diets

indicates that they provide some benefit, particularly in diabetic populations. Forexample, Raben et al 212 reported that subjectsmaintaining a low fat/high fiber diet for 11weeks lost about 3 lbs of weight and 3.5 lbsof fat. Other studies report either nosignificant effects or modest amounts of fatloss. High fiber/low fat diets have also beenfound to help reduce cholesterol.Consequently, although maintaining a low fat/ high fiber diet may have some health

benefits, they do not appear to promote asignificant amount of weight or fat loss.

Calcium. Research has indicated that calciummodulates 1,25-diydroxyvitamin D whichserves to regulate intracellular calcium levelsin fat cells 213-215 . Increasing dietaryavailability of calcium reduces 1,25-diydroxyvitamin D and promotes reductionsin fat mass in animals 213-215 . Dietary calciumhas been shown to suppress fat metabolismand weight gain during periods of high caloricintake 213, 216 . Further, increasing calciumintake has been shown to increase fat

metabolism and preserve thermogenesisduring caloric restriction 213, 216, 217 . Insupport of this theory, Davies and colleagues218 reported that dietary calcium wasnegatively correlated to weight and thatcalcium supplementation (1,000 mg/d)


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loss (38-64%) compared to subjects on a lowcalcium diet (400-500 mg/d). These findingsand others suggest a strong relationship

between calcium intake and fat loss.

Phosphates. The role of sodium and calcium phosphate on energy metabolism and exercise performance has been studied for decades 36.These studies have revealed that sodium

phosphate supplementation appears to possessergogenic properties particularly in endurance

exercise events219, 220

. More recently, phosphate supplementation has also beensuggested to affect energy expenditure. Forexample, Kaciuba-Uscilko and colleagues 221 reported that phosphate supplementationduring a 4-week weight loss programincreased resting metabolic rate (RMR) andrespiratory exchange ratio (suggesting greatercarbohydrate utilization and caloricexpenditure) during submaximal cyclingexercise. In addition, Nazar and coworkers222 reported that phosphate supplementationduring an 8-week weight loss programincreased RMR by 12-19% and prevented anormal decline in thyroid hormones.Although the rate of weight loss was similarin this trial, results suggest that phosphatesupplementation may influence metabolic rate

possibly by affecting thyroid hormones.Consequently, it is possible that phosphatecould serve as a potential thermogenicnutrient in non-ephedrine based supplements.Additional research is necessary to test thishypothesis.

Green Tea Extr act. Green tea is one of themore interesting herbal supplements that hasrecently been suggested to affect weight loss.Green tea contains high amounts of caffeineand catechin polyphenols. Research suggeststhat catechin polyphenols possess antioxidant

day) significantly increased 24-hour energyexpenditure and fat utilization in humans.The thermogenic effects of green tea

supplementation were much greater thanwhen an equivalent amount of caffeine wasevaluated suggesting a synergistic effect.Theoretically, increases in energy expendituremay help individuals lose weight and/ormanage body composition.

Calciu m Pyruvate. Calcium Pyruvate is

supplement that hit the scene about five or sixyears ago with great promise. The theoreticalrationale was based on studies from the early1990s that reported that calcium pyruvatesupplementation (16 25 g/d with or withoutdihydroxyacetone phosphate [DHAP])

promoted fat loss in overweight/obese patients following a medially supervisedweight loss program 226-228 . Although themechanism for these findings was unclear, theresearchers speculated that it might be relatedto appetite suppression and/or alteredcarbohydrate and fat metabolism. Sincecalcium pyruvate is very expensive, severalstudies have attempted to determine whetheringesting smaller amounts of calcium

pyruvate (6-10 g/d) affect body compositionin untrained and trained populations. Resultsof these studies are mixed. Kalman andcolleagues 229 reported that calcium pyruvatesupplementation (6 g/d for 6-weeks)significantly decreased body weight (-1.2 kg),

body fat (-2.5 kg), and percent body fat (-2.7%). However, Stone and colleagues 230 reported that pyruvate supplementation did

not affect hydrostatically determined bodycomposition during 5-weeks of in-seasoncollege football training. These findingsindicate that although there is somesupportive data indicating that calcium

pyruvate supplementation may enhance fat


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relatively new supplement. It is purported toaffect glucose and fat metabolism as well asinhibit sweet cravings. In support of these

contentions, some recent data have been published by Shigematsu and colleagues 231,232 indicating that short and long-term oralsupplementation of gymnema sylvestre in ratsfed normal and high-fat diets may have some

positive effects on fat metabolism, blood lipidlevels, and/or weight gain/fat deposition.Although these findings are interesting, we

are aware of no published studies that haveevaluated the effects of gymnema sylvestresupplementation on lipid metabolism or bodycomposition in humans. Consequently, moreresearch is needed before conclusions can bedrawn.

Chitosan. Chitosan has been marketed as aweight loss supplement for several years. It is

purported to inhibit fat absorption and lowercholesterol. Several animal studies reportdecreased fat absorption, increased fecal fatcontent, and/or lower cholesterol followingchitosan feedings 233-236 . However, the effectsin humans appear to be less impressive. Forexample, although there is some datasuggesting that chitosan supplementation maylower blood lipids in humans, 237 other studiesreport no effects on fecal fat content 238or

body composition alterations 239, 240 whenadministered to people following their normaldiet. It seems that people may be prone to eatmore when they know they are taking a fat

blocking supplement in a similar way peopletend to eat more when the consume low-fat

foods. Whether chitosan may promote greateramounts of fat loss when people are put on acontrolled diet is unclear.

Non-Eph edra Contain in g Thermogenics.Since the safety of ephedra supplements has

that synephrine may increase metabolismwithout significantly affecting heart rate and

blood pressure. However, it is unclear

whether dietary supplementation of CitrusAurantum may enhance weight loss. Anumber of thyroid stimulating supplementshave also been marketed. Most containnutrients (e.g., guggulsterones, 3, 5-Diiodo-L-Thyronine, etc.) believed to enhance theconversion of triidiothyronine (T3) tothyroxin (T4) or increase availability of T2

(diidiothyronine) or T3 which wouldtheoretically increase basal metabolic rate(resting caloric expenditure) and promoteweight loss 243, 244 . However, while thyroidmedications can effectively increasemetabolic rate 245, it is unclear whether thesesupplements can promote weight loss.Additionally, several of these types ofsupplements have been recently pulled by theFDA due to adverse health outcomes reportedamong people using these types ofsupplements particularly if they also containusnic acid.

Phosphatidyl Cholin e (Lecithin). Choline isconsidered an essential nutrient that is neededfor cell membrane integrity and to facilitatethe movement of fats in and out of cells. It isalso a component of the neurotransmitteracetylcholine and is needed for normal brainfunctioning, particularly in infants. For thisreason, phosphatidyl choline (PC) has been

purported as a potentially effectivesupplement to promote fat loss as well asimprove neuromuscular function. There is

some data from animal studies that supportsthe potential value of PC as a weight losssupplement 246. There has also been someinterest in determining the potential ergogenicvalue of choline supplementation duringendurance exercise 247, 248 . However, it is


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liver metabolism, fat metabolism, and fatdeposition in animals 249, 250 . There has also

been interest in determining whether betaine

supplementation may help lowerhomocysteine levels which has recently beenidentified as a marker of risk to heart disease251 . For this reason, betaine supplements have

been marketed as a supplement designed to promote heart health as well as a weight loss.Although the potential theoretical rationale of

betaine supplementation is interesting, it is

currently unclear whether betainesupplementation may serve as an effectiveweight loss supplement in humans.

Coleus F orskohli i (F orskolin). Forskolin isanother relatively new weight losssupplement. Forskolin is a plant native toIndia that has been used for centuries intraditional Ayurvedic medicine primarily totreat skin disorders and respiratory problems252, 253 . A considerable amount of researchhas evaluated the physiological and potentialmedical applications of forskolin over the last25 years. Forskolin has been reported toreduce blood pressure, increase the heartsability to contract, help inhibit plateletaggregation, improve lung function, and aidin the treatment of glaucoma 252-254 . Withregard to weight loss, forskolin has beenreported to increase cyclic AMP and therebystimulate fat metabolism 255-257 .Theoretically, forskolin may therefore serveas an effective weight loss supplement. Insupport of this theory, Sabinsa Corporation(the principle source for Forskolin in the

U.S.) reported that forskolin supplementation(250 mg of a 10% forskolin extract takentwice daily for 8-weeks) administered in anopen label manner to six overweight females

promoted a 7.25 lbs loss in body weight and a7.7% decrease bioelectrical impedance (BIA)

coleus forskohlii in overweight women helpedmaintain weight and was not associated withany clinically significant adverse events 259.

Additional research is needed beforeconclusions can be drawn.

Dehydroepiandrosteron e (DH EA ) and 7- Keto DH EA. Dehydroepiandrosterone(DHEA) and its sulfated conjugate DHEASrepresent the most abundant adrenal steroidsin circulation 260. Although, DHEA is

considered a weak androgen, it can beconverted to the more potent androgenstestosterone and dihydrotestosterone intissues. In addition, DHEAS can beconverted into androstenedione andtestosterone. DHEA levels have beenreported to decline with age in humans 261.The decline in DHEA levels with aging has

been associated with increased fataccumulation and risk to heart disease 262 .Since DHEA is a naturally occurringcompound, it has been suggested that dietarysupplementation of DHEA may help maintainDHEA availability, maintain and/or increasetestosterone levels, reduce body fataccumulation, and/or reduce risk to heartdisease as one ages 260, 262 . Although animalstudies have generally supported this theory,the effects of DHEA supplementation on

body composition in human trials have beenmixed. For example, Nestler and coworkers263 reported that DHEA supplementation(1,600 mg/d for 28-d) in untrained healthymales promoted a 31% reduction in

percentage of body fat. However, Vogiatzi

and associates264

reported that DHEAsupplementation (40 mg/d for 8 wks) had noeffect on body weight, percent body fat, orserum lipid levels in obese adolescents. Morerecently, 7-keto DHEA has been marketed asa potentially more effective form of DHEA.


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observed on thyroid stimulating hormone(TSH), T4, or other hormones. Althoughmore research is needed, these findings

provide some support to contentions that 7-keto DHEA may serve as an effective weightloss supplement. However, additionalresearch is needed before definitiveconclusions can be made.

Psychotropic Nutr ients/H erbs. This is arelatively new type of weight loss supplement

category. Psychotropic nutrients/herbs oftencontain things like St. Johns Wart, Kava,Ginkgo Biloba, Ginseng, and L-Tyrosine.They are believed to serve as naturallyoccurring antidepressants, relaxants, andmental stimulants. The theoretical rationaleregarding weight loss is that they may help

people fight depression or maintain mentalalertness while dieting. Although a number ofstudies support potential role as naturallyoccurring psychotropics or stimulants, the

potential value in promoting weight loss isunclear.

Apparently Ineffective

Chromium. Interest in chromium as a potential body composition modifieremanated from studies suggesting thatchromium may enhance insulinsensitivity/glucose disposal in diabetics.Initial studies reported that chromiumsupplementation during resistance trainingimproved fat loss and gains in lean body mass128-130 . However, recent studies using more

accurate methods of assessing bodycomposition have mostly reported no effectson body composition in healthy non-diabeticindividuals 131-137 . For example, Walker andcolleagues 132 reported that chromiumsupplementation (200 g/d for 14-weeks) did

Conjugated L inoleic A cids (CLA ). CLA is aterm used to describe a group of positionaland geometric isomers of linoleic acid that

contain conjugated double bonds. AddingCLA to the diet has been reported to possesssignificant health benefits in animals 138, 266 .In terms of weight loss, CLA feedings toanimals have been reported to markedlydecrease body fat accumulation 138, 139, 143 .Consequently, CLA has been marketed as ahealth and weight loss supplement since the

mid 1990s. Although basic research inanimals is very promising, the effect of CLAsupplementation in humans is less clear.There are some data suggesting that CLAsupplementation may modestly promote fatloss and/or increases in lean mass 144, 267-271 .However, other studies indicate that CLAsupplementation (1.7 to 12 g/d for 4-weeks to6-months) has limited to no effects on bodycomposition alterations in untrained or trained

populations 144, 146, 147, 267, 272-274 . The reasonfor the discrepancy in research findings has

been suggested to be due to differences in purity and the specific isomer studied. Forinstance, early studies in humans showing noeffect used CLA that contained all 24isomers. Today, most labs studying CLA use50-50 mixtures containing the trans-10,cis-12and cis-9,trans-11 isomers, the former ofwhich being recently implicated in positivelyaltering body composition. In our view,although CLA supplementation may have

promise to promote general health, additionalresearch is needed to determine if specificisomers of CLA may affects body

composition in humans before conclusionscan be made.

Garcini a Cambogia (H CA). HCA is anutrient that has been hypothesized toincrease fat oxidation by inhibiting citrate


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reported that HCA supplementation sparedcarbohydrate utilization and promoted lipidoxidation during exercise in mice. However,

Kriketos and associates277

reported that HCAsupplementation (3 g/d for 3-days) did notaffect resting or post-exercise energyexpenditure or markers of lipolysis in healthymen. Likewise, Heymsfield and coworkers278 reported that HCA supplementation (1.5g/d for 12-weeks) while maintaining a lowfat/high fiber diet did not promote greater

weight or fat loss than subjects on placebo.Finally, Mattes and colleagues 279 reportedthat HCA supplementation (2.4 g/d for 12-weeks) did not affect appetite, energy intake,or weight loss. These findings suggest thatHCA supplementation does not appear to

promote fat loss in humans.

L-Carnitine. Carnitine serves as an importanttransporter of fatty acids from the cytosol intothe mitochondria of the cell. Theoretically,increasing cellular levels of carnitine wouldthereby enhance transport of fats into themitochondria and fat metabolism. For thisreason, L-carnitine has been one of the mostcommon nutrients found in various weightloss supplements. Over the years, a numberof studies have been conducted on the effectsof L-carnitine supplementation on fatmetabolism, exercise capacity and bodycomposition. Although there is some datashowing that L-carnitine supplementationmay be beneficial for some patient

populations, most well controlled studiesindicate that L-carnitine supplementation does

not affect muscle carnitine content, fatmetabolism, and/or weight loss in overweightor trained subjects 280 . For example, Villaniet al 281 reported that L-carnitinesupplementation (2 g/d for 8-weeks) did notaffect weight loss, body composition, or

equisetum arvense, arctostaphylos uva-ursi,arctium lappa and silene saxifraga infusionmay affect diuresis in animals 282, 283 . Two

studies presented at the 2001 AmericanCollege of Sports Medicine meeting 284, 285 indicated that although herbal diuretics

promoted a small amount of dehydration(about 0.3% in one day), they were not nearlyas effective as a common diuretic drug (about3.1% dehydration in one day). Consequently,although more research is needed, the

potential value of herbal diuretics as a weightloss supplement appears limited.

Perf orman ce Enhancement Supplements

A number of nutritional supplements have been proposed to enhance exercise performance. Some of these nutrients have been described above. Table 3 categorizesthe proposed ergogenic nutrients intoapparently safe and effective, possiblyeffective, too early to tell, and apparentlyineffective. Weight gain supplements

purported to increase muscle mass may alsohave ergogenic properties if they also

promote increases in strength. Similarly,some sports may benefit from reductions infat mass. Therefore, weight loss supplementsthat help athletes manage body weight and/orfat mass may also posses some ergogenic

benefit. The following describes whichsupplements may or may not affect

performance that were not previouslydescribed. Based on this analysis, Table 4summarizes the general nutritional

recommendations for athletes and whichdietary supplements may help power andendurance athletes.



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Sports Nutrition Review Journal 1 (1):1-44 2004 ( www sportsnutritionsociety org ) 27


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bicarbonate as it may cause gastrointestinaldistress.

Caffeine. Caffeine is a naturally derivedstimulant found in many nutritionalsupplements typically as Gaurana, Bissey

Nut, or Kola. Caffeine can also be found incoffee, tea, soft drinks, energy drinks, andchocolate. Studies indicate that ingestion ofcaffeine (e.g., 3-9 mg/kg taken 30 90minutes before exercise) can spare

carbohydrate use during exercise and therebyimprove endurance exercise capacity 295, 299 .People who drink caffeinated drinksregularly, however, appear to experience lessergogenic benefits from caffeine 300.Additionally, some concern has beenexpressed that ingestion of caffeine prior toexercise may contribute to dehydrationalthough recent studies have not supportedthis concern 301-303 . Caffeine doses above 9mg/kg can result in urinary caffeine levelsthat surpass the doping threshold for manysport organizations. Suggestions that there isno ergogenic value to caffeinesupplementation is not supported by the

preponderance of available scientific studies.

Possibly Effective

Post-Exercise Carbohydrate and Protein.Ingesting carbohydrate and protein followingexercise enhances carbohydrate storage and

protein synthesis. Theoretically, ingestingcarbohydrate and protein following exercisemay lead to greater training adaptations. In

support of this theory, Esmarck andcoworkers 93 found that ingestingcarbohydrate and protein immediatelyfollowing exercise doubled trainingadaptations in comparison to waiting until 2-hours to ingest carbohydrate and protein.

Glutamine. As described above, glutaminehas been shown to influence protein synthesisand help maintain the immune system.

Theoretically, glutamine supplementationduring training should enhance gains instrength and muscle mass as well as helpathletes tolerate training to a better degree.Although there is some evidence thatglutamine supplementation with protein canimprove training adaptations, more research isneeded to determine the ergogenic value in

athletes.Essential Amin o Acids (EAA). Ingestion of3-6 grams of EAA following resistanceexercise has been shown to increase proteinsynthesis 84-92 . Theoretically, ingestion ofEAA after exercise should enhance gains instrength and muscle mass during training.While there is sound theoretical rationale, it iscurrently unclear whether following thisstrategy would lead to greater trainingadaptations and/or whether EAAsupplementation would be better than simplyingesting carbohydrate and a quality proteinfollowing exercise.

Branched Chain A min o Acids (BCAA ).

Ingestion of BCAA (e.g., 6-10 grams perhour) with sports drinks during prolongedexercise would theoretically improve

psychological perception of fatigue (i.e.,central fatigue). Although there is strongrationale, the effects of BCAAsupplementation on exercise performance ismixed with some studies suggesting an

improvement and others showing no effect36

.More research is needed before conclusionscan be drawn.

Calcium -HMB. HMB supplementation has been reported to improve training adaptations



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Glycerol. Ingesting glycerol with water has been reported to increase fluid retention 305 .Theoretically, this should help athletes

prevent dehydration during prolongedexercise and improve performance

particularly if they are susceptible todehydration. Although studies indicate thatglycerol can significantly enhance body fluid,studies are mixed on whether it can improveexercise capacity 52, 306-311 .

Ephedrine/Caffeine.Most research hasevaluated the effects of ingesting ephedrine

and caffeine (EC) supplements on weightloss. However, since ephedra and caffeine arestimulants and caffeine has been shown tohave ergogenic properties, there has also beeninterest in the potential ergogenic value ofEC. Recent research has shown that ingestionof low to moderate amounts of synthetic ECsupplements generally improves enduranceand high intensity exercise performance withno apparent adverse effects 312-316 . However,it is unclear whether dietary supplementscontaining botanical ephedrine (i.e., ephedra)and caffeine (e.g., kola nut) have similareffects on performance. Further, since mostsport organizations ban use of ephedrine the

potential use in athletes appears limited.

Too Early to Tell

A number of supplements purported toenhance performance and/or trainingadaptation fall under this category. Thisincludes the weight gain and weight loss

supplements listed in Table 3 as well as thefollowing supplements not previouslydescribed in this category.

M edium Chain Tr iglyceri des (M CT).MCTs are shorter chain fatty acids that can

Ribose. Ribose is a 3-carbon carbohydratethat is involved in the synthesis of adenosinetriphosphate (ATP) in the muscle (the useable

form of energy). Clinical studies have shownthat ribose supplementation can increaseexercise capacity in heart patients 323-327 . Forthis reason, ribose has been suggested to be anergogenic aid for athletes. Although moreresearch is needed, most studies show noergogenic value of ribose supplementation onexercise capacity in health untrained or

trained populations328-330

.Apparently Ineffective

Inosine. Inosine is a building block for DNAand RNA that is found in muscle. Inosine hasa number of potentially important roles thatmay enhance training and/or exercise

performance 331 . Although there is sometheoretical rationale, available studies indicatethat inosine supplementation has no apparentaffect on exercise performance capacity 332-334.

Supplements to Promote General H ealth

In addition to the supplements previously

described, several nutrients have beensuggested to help athletes stay healthy duringintense training. For example, the AmericanMedical Association recently recommendedthat all Americans ingest a daily low-dosemultivitamin in order to ensure that people geta sufficient amount of vitamins and mineralsin their diet. Although one-a-day vitamin

supplementation has not been found toimprove exercise capacity in athletes, it maymake sense to take a daily vitaminsupplement for health reasons. Glucosomineand chondroitin have been reported to slowcartilage degeneration and reduce the degree



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p ( ) ( p y g ) 29

enhance immune function 42, 337-339 .Similarly, nutrients such as vitamins E and Cmay help restore overwhelmed anti-oxidant

defenses exhibited by athletes and reduce therisk of numerous chronic diseases 340 .Creatine, calcium -HMB, BCAA, and L-carnitine have been shown to help athletestolerate heavy training periods 36, 74, 80, 81, 83,341-344 . Finally, omega-3 fatty acids, insupplemental form, are now endorsed by theAmerican Heart Association for heart health

in certain individuals345

. This supportivesupplement position stems from: 1.) aninability to consume cardio-protectiveamounts by diet alone; and, 2.) the mercurycontamination sometimes present in whole-food sources of DHA (docosahexaenoic acid)and EPA (eicosapentaenoic acid) found infatty fish. Consequently, prudent use ofthese types of nutrients at various timesduring training may help athletes stay healthyand/or tolerate training to a greater degree 37.

SUMMARY

Numerous nutritional and herbal products aremarketed to promote weight gain, weight loss,and/or improve performance. Most have a

theoretical basis for use but little datasupporting safety and efficacy in athletes. Anumber are heavily marketed despite dataindicating that they do not affect bodycomposition, performance, and/or trainingadaptations at the dosages recommended. Itis in these particular situations thatunsupported claims explicitly or implicitly

endorsed by sport nutrition specialistsconstitute fraud and/ or quackery. Prudent

training, maintaining an energy balance andnutrient dense diet, proper timing of nutrientintake, and obtaining adequate rest are the

cornerstones to enhancing performance and/ortraining adaptations. Use of a limited numberof nutritional supplements that research hassupported can help improve energyavailability (e.g., sports drinks, carbohydrate,creatine, caffeine, etc) and/or promoterecovery (carbohydrate, protein, essentialamino acids, etc) can provide additional

benefit in certain instances. The sportnutrition specialist should stay up to dateregarding the role of nutrition on exercise sothey can provide honest and accurateinformation to their students, clients, and/orathletes about the role of nutrition and dietarysupplements on performance and training.Furthermore, the sport nutrition specialistshould actively participate in exercisenutrition research; write unbiased scholarlyreviews for journals and lay publications; helpdisseminate the latest research findings to the

public so they can make informed decisionsabout appropriate methods of exercise,dieting, and/or whether various nutritionalsupplements can affect health, performance,and/or training; and, disclose any commercial

or financial conflicts of interest during such promulgations to the public. Finally, sportnutrition specialists can challenge companieswho sell exercise equipment and/or nutritionalsupplements to develop scientifically based

products, conduct research on their products,and honestly market the results of studies soconsumers can make informed decisions.

REFERENCES

1. Leutholtz B, Kreider RB. Exercise and Sport Nutrition. In: Wilson T, Temple N, eds. Nutritional Health. Totowa, NJ:Humana Press Inc ; 2001:207 39



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9. National Library of Medicine/Pub Med. 2002;Available: (http://www.ncbi.nlm.nih.gov/PubMed/.10. Sherman WM, Jacobs KA, Leenders N. Carbohydrate metabolism during endurance exercise. In: Kreider RB, Fry AC,

O'Toole ML, eds. Overtraining in Sport. Champaign: Human Kinetics Publishers; 1998:289-308.11. Berning JR. Energy intake, diet, and muscle wasting. In: Kreider RB, Fry AC, O'Toole ML, eds. Overtraining in Sport.

Champaign: Human Kinetics; 1998:275-88.12. Kreider RB, Fry AC, O'Toole ML. Overtraining in Sport. Champaign, IL.: Human Kinetics Publishers; 1998.13. Kreider RB. Physiological considerations of ultraendurance performance. Int J Sport Nutr 1991;1(1):3-27.14. Brouns F, Saris WH, Beckers E, et al. Metabolic changes induced by sustained exhaustive cycling and diet manipulation. Int J

Sports Med 1989;10 Suppl 1:S49-62.15. Brouns F, Saris WH, Stroecken J, et al. Eating, drinking, and cycling. A controlled Tour de France simulation study, Part II.

Effect of diet manipulation. Int J Sports Med 1989;10 Suppl 1:S41-8.16. Lemon PW, Tarnopolsky MA, MacDougall JD, Atkinson SA. Protein requirements and muscle mass/strength changes during

intensive training in novice bodybuilders. J Appl Physiol 1992;73(2):767-75.17. Tarnopolsky MA, MacDougall JD, Atkinson SA. Influence of protein intake and training status on nitrogen balance and lean

body mass. J Appl Physiol 1988;64(1):187-93.18. Tarnopolsky MA, Atkinson SA, MacDougall JD, Chesley A, Phillips S, Schwarcz HP. Evaluation of protein requirements for

trained strength athletes. J Appl Physiol 1992;73(5):1986-95.19. Tarnopolsky MA. Protein and physical performance. Curr Opin Clin Nutr Metab Care 1999;2(6):533-7.20. Kreider RB. Effects of protein and amino acid supplementation on athletic performance. Sportscience 1999. Available:

http://www.sportsci.org/jour/9901/rbk.html;3(1) .21. Kreider RB, Kleiner SM. Protein supplements for athletes: need vs. convenience. Your Patient & Fitness 2000;14(6):12-8.22. Bucci L, Unlu L. Proteins and amino acid supplements in exercise and sport. In: Driskell J, Wolinsky I, eds. Energy-Yielding

Macronutrients and Energy Metabolism in Sports Nutrition. Boca Raton, FL: CRC Press; 2000:191-212.23. Boirie Y, Dangin M, Gachon P, Vasson MP, Maubois JL, Beaufrere B. Slow and fast dietary proteins differently modulate

postprandial protein accretion. Proc Natl Acad Sci U S A 1997;94(26):14930-5.24. Boirie Y, Gachon P, Cordat N, Ritz P, Beaufrere B. Differential insulin sensitivities of glucose, amino acid, and albumin

metabolism in elderly men and women. J Clin Endocrinol Metab 2001;86(2):638-44.25. Boirie Y, Gachon P, Corny S, Fauquant J, Maubois JL, Beaufrere B. Acute postprandial changes in leucine metabolism as

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