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  • 8/20/2019 Posizion of the American Dietetic Associetion - Vegetarian Diets

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    from the association

    Position of the American Dietetic Association:

     Vegetarian Diets

    ABSTRACTIt is the position of the American Di-etetic Association that appropriatelyplanned vegetarian diets, including total vegetarian or vegan diets, arehealthful, nutritionally adequate, andmay provide health benefits in theprevention and treatment of certaindiseases. Well-planned vegetarian di-ets are appropriate for individuals

    during all stages of the life cycle, in-cluding pregnancy, lactation, infancy,childhood, and adolescence, and forathletes. A vegetarian diet is definedas one that does not include meat (in-cluding fowl) or seafood, or productscontaining those foods. This articlereviews the current data related tokey nutrients for vegetarians includ-ing protein, n-3 fatty acids, iron, zinc,iodine, calcium, and vitamins D andB-12. A vegetarian diet can meet cur-rent recommendations for all of thesenutrients. In some cases, supplements

    or fortified foods can provide usefulamounts of important nutrients. An ev-idence-based review showed that veg-etarian diets can be nutritionally ad-equate in pregnancy and result inpositive maternal and infant healthoutcomes. The results of an evidence-based review showed that a vegetar-ian diet is associated with a lower riskof death from ischemic heart disease. Vegetarians also appear to have lowerlow-density lipoprotein cholesterol lev-els, lower blood pressure, and lowerrates of hypertension and type 2 diabe-tes than nonvegetarians. Furthermore,

     vegetarians tend to have a lower bodymass index and lower overall cancerrates. Features of a vegetarian dietthat may reduce risk of chronic diseaseinclude lower intakes of saturated fatand cholesterol and higher intakes of fruits, vegetables, whole grains, nuts,soy products, fiber, and phytochemi-

    cals. The variability of dietary practicesamong vegetarians makes individualassessment of dietary adequacy essen-tial. In addition to assessing dietary ad-

    equacy, food and nutrition profession-als can also play key roles in educating  vegetarians about sources of specificnutrients, food purchase and prepara-tion, and dietary modifications to meettheir needs. J Am Diet Assoc. 2009;109:1266-1282.

    POSITION STATEMENT

     It is the position of the American Di- etetic Association that appropriately planned vegetarian diets, includingtotal vegetarian or vegan diets, arehealthful, nutritionally adequate, andmay provide health benefits in the pre-vention and treatment of certain dis- eases. Well-planned vegetarian dietsare appropriate for individuals duringall stages of the lifecycle, including pregnancy, lactation, infancy, child-hood, and adolescence, and for athletes.

    VEGETARIAN DIETS IN PERSPECTIVE

     A vegetarian is a person who does noteat meat (including fowl) or seafood,

    or products containing these foods.The eating patterns of vegetariansmay vary considerably. The lacto-ovo- vegetarian eating pattern is based on

    grains, vegetables, fruits, legumes,seeds, nuts, dairy products, and eggs.The lacto-vegetarian excludes eggsas well as meat, fish, and fowl. The vegan, or total vegetarian, eating pat-tern excludes eggs, dairy, and otheranimal products. Even within thesepatterns, considerable variation mayexist in the extent to which animalproducts are excluded.

    Evidence-based analysis was usedto evaluate existing research on typesof vegetarian diets (1). One questionfor evidence-analysis was identified:What types of vegetarian diets areexamined in the research? The com-plete results of this evidence-basedanalysis can be found on the Ameri-can Dietetic Association’s Evidence Analysis Library (EAL) Web site(www.adaevidencelibrary.com) andare summarized below.

    EAL Conclusion Statement:   The twomost common ways of defining vege-tarian diets in the research are vegandiets: Diets devoid of all flesh foods;

    This American Dietetic Association (ADA) position paper includes theauthors’ independent review of the literature in addition to systematicreview conducted using the ADA’s Evidence Analysis Process and informa-tion from the Evidence Analysis Library. Topics from the Evidence AnalysisLibrary are clearly delineated. The use of an evidence-based approachprovides important added benefits to earlier review methods. The majoradvantage of the approach is the more rigorous standardization of reviewcriteria, which minimizes the likelihood of reviewer bias and increases theease with which disparate articles may be compared. For a detailed descrip-tion of the methods used in   the evidence analysis process, access ADA’s

    Evidence Analysis Process at http://adaeal.com/eaprocess/ .Conclusion Statements are assigned a grade by an expert work group

    based on the systematic analysis and evaluation of the supporting researchevidence. Grade IGood; Grade IIFair; Grade IIILimited; GradeIV Expert Opinion Only; and Grade V Not Assignable (because there isno evidence to support or refute the conclusion).

    Evidence-based information for this and other topics can be found athttps://www.adaevidencelibrary.com and subscriptions for nonmembers areavailable for purchase at  https://www.adaevidencelibrary.com/store.cfm.

    0002-8223/09/10907-0019$36.00/0doi: 10.1016/j.jada.2009.05.027 

    1266   Journal of the AMERICAN DIETETIC ASSOCIATION   ©  2009 by the American Dietetic Association

    http://www.adaevidencelibrary.com/http://adaeal.com/eaprocess/http://adaeal.com/eaprocess/http://adaeal.com/eaprocess/https://www.adaevidencelibrary.com/https://www.adaevidencelibrary.com/https://www.adaevidencelibrary.com/store.cfmhttps://www.adaevidencelibrary.com/store.cfmhttps://www.adaevidencelibrary.com/store.cfmhttps://www.adaevidencelibrary.com/store.cfmhttps://www.adaevidencelibrary.com/store.cfmhttps://www.adaevidencelibrary.com/http://adaeal.com/eaprocess/http://www.adaevidencelibrary.com/

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    and vegetarian diets: Diets devoid of all flesh foods, but also include egg (ovo) and/or dairy (lacto) products.

    However, these very broad cat-egories mask important variationswithin vegetarian diets and dietarypractices. These variations within

     vegetarian diets make absolute cat-egorization of vegetarian dietarypractices difficult and may be one of the sources of unclear relationshipsbetween vegetarian diets and otherfactors.  Grade IIFair.

    In this article, the term   vegetarianwill be used to refer to people choosing a lacto-ovo-, lacto-, or vegan vegetariandiet unless otherwise specified.

    Whereas lacto-ovo-, lacto-, and vegan-vegetarian diets are thosemost commonly studied, practitionersmay encounter other types of vegetar-

    ian or near-vegetarian diets. For ex-ample, people choosing macrobioticdiets typically describe their diet as vegetarian. The macrobiotic diet isbased largely on grains, legumes, and vegetables. Fruits, nuts, and seedsare used to a lesser extent. Some peo-ple following a macrobiotic diet arenot truly vegetarian because they eatlimited amounts of fish. The tradi-tional Asian-Indian diet is predomi-nantly plant based and is frequentlylacto-vegetarian although changes of-ten occur with acculturation, includ-ing greater consumption of cheese

    and a movement away from a vege-tarian diet. A raw foods diet may be a vegan diet, consisting mainly or ex-clusively of uncooked and unproc-essed foods. Foods used include fruits, vegetables, nuts, seeds, and sproutedgrains and beans; in rare instancesunpasteurized dairy products andeven raw meat and fish may be used.Fruitarian diets are vegan dietsbased on fruits, nuts, and seeds. Veg-etables that are classified botanicallyas fruits like avocado and tomatoesare commonly included in fruitarian

    diets; other vegetables, grains, beans,and animal products are excluded.Some people will describe them-

    selves as vegetarian but will eat fish,chicken, or even meat. These self-de-scribed vegetarians may be identifiedin research studies as semivegetarians.Individual assessment is required toaccurately evaluate the nutritionalquality of the diet of a vegetarian or aself-described vegetarian.

    Common reasons for choosing a vegetarian diet include health consid-

    erations, concern for the environ-ment, and animal welfare factors. Vegetarians also cite economic rea-sons, ethical considerations, worldhunger issues, and religious beliefs astheir reasons for following their cho-sen eating pattern.

    Consumer Trends

    In 2006, based on a nationwide poll,approximately 2.3% of the US adultpopulation (4.9 million people) consis-tently followed a vegetarian diet,stating that they never ate meat, fish,or poultry (2). About 1.4% of the USadult population was vegan (2). In2005, according to a nationwide poll,3% of 8- to 18-year-old children andadolescents were vegetarian; close to1% were vegan (3).

    Many consumers report an interestin vegetarian diets (4) and 22% reportregular consumption of meatless sub-stitutes for meat products (5). Addi-tional evidence for the increasing in-terest in vegetarian diets includes theemergence of college courses on vege-tarian nutrition and on animal rights;the proliferation of Web sites, period-icals, and cookbooks with a vegetar-ian theme; and the public’s attitudetoward ordering a vegetarian mealwhen eating away from home.

    Restaurants have responded to thisinterest in vegetarian diets. A survey

    of chefs found that vegetarian disheswere considered “hot” or “a perennialfavorite” by 71%; vegan dishes by 63%(6). Fast-food restaurants are begin-ning to offer salads, veggie burgers,and other meatless options. Most uni- versity foodservices offer vegetarianoptions.

    New Product Availability

    The US market for processed vegetar-ian foods (foods like meat analogs,nondairy milks, and vegetarian en-

    trees that directly replace meat orother animal products) was estimatedto be $1.17 billion in 2006 (7). Thismarket is forecast to grow to $1.6 bil-lion by 2011 (7).

    The availability of new products, in-cluding fortified foods and conveniencefoods, would be expected to have animpact on the nutrient intake of vege-tarians who choose to eat these foods.Fortified foods such as soy milks, meatanalogs, juices, and breakfast cerealsare continually being added to the mar-

    ketplace with new levels of fortifica-tion. These products and dietary sup-plements, which are widely available insupermarkets and natural foods stores,can add substantially to vegetarians’intakes of key nutrients such as cal-cium, iron, zinc, vitamin B-12, vitamin

    D, riboflavin, and long-chain n-3 fattyacids. With so many fortified productsavailable today, the nutritional statusof the typical vegetarian today wouldbe expected to be greatly improvedfrom that of a vegetarian 1 to 2 decadesago. This improvement would beenhanced by the greater awarenessamong the vegetarian population of what constitutes a balanced vegetariandiet. Consequently older research datamay not represent the nutritional sta-tus of present-day vegetarians.

    Health Implications of Vegetarian Diets

     Vegetarian diets are often associatedwith a number of health advantages,including lower blood cholesterol levels,lower risk of heart disease, lower bloodpressure levels, and lower risk of hy-pertension and type 2 diabetes. Vege-tarians tend to have a lower body massindex (BMI) and lower overall cancerrates. Vegetarian diets tend to be lowerin saturated fat and cholesterol, andhave higher levels of dietary fiber, mag-nesium and potassium, vitamins C andE, folate, carotenoids, flavonoids, and

    other phytochemicals. These nutri-tional differences may explain some of the health advantages of those follow-ing a varied, balanced vegetarian diet.However, vegans and some other vege-tarians may have lower intakes of vita-min B-12, calcium, vitamin D, zinc, andlong-chain n-3 fatty acids.

    Recently, outbreaks of food-borne ill-ness associated with the consumptionof domestically grown and importedfresh fruits, sprouts, and vegetablesthat have been contaminated by   Sal-monella,   Escherichia coli, and other

    micro-organisms have been seen.Health advocacy groups are calling forstricter inspection and reporting proce-dures and better food-handling prac-tices.

    NUTRITION CONSIDERATIONS FORVEGETARIANS

    Protein

    Plant protein can meet protein re-quirements when a variety of plantfoods is consumed and energy needs

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    are met. Research indicates that anassortment of plant foods eaten overthe course of a day can provide allessential amino acids and ensure ad-equate nitrogen retention and use inhealthy adults; thus, complementaryproteins do not need to be consumed

    at the same meal (8). A meta-analysis of nitrogen bal-

    ance studies found no significant dif-ference in protein needs due to thesource of dietary protein (9). Based onthe protein digestibility-correctedamino acid score, which is the stan-dard method for determining proteinquality, other studies have found thatalthough isolated soy protein canmeet protein needs as effectively asanimal protein, wheat protein eatenalone, for example, may result in areduced efficiency of nitrogen utiliza-

    tion (10). Thus, estimates of proteinrequirements of vegans may vary, de-pending to some degree on dietarychoices. Food and nutrition profes-sionals should be aware that proteinneeds might be somewhat higherthan the Recommended Dietary Al-lowance in those vegetarians whosedietary protein sources are mainlythose that are less well digested, suchas some cereals and legumes (11).

    Cereals tend to be low in lysine, anessential amino acid (8). This may berelevant when evaluating diets of in-dividuals who do not consume animal

    protein sources and when diets arerelatively low in protein. Dietary ad- justments such as the use of morebeans and soy products in place of other protein sources that are lowerin lysine or an increase in dietary pro-tein from all sources can ensure anadequate intake of lysine.

     Although some vegan women haveprotein intakes that are marginal,typical protein intakes of lacto-ovo- vegetarians and of vegans appear tomeet and exceed requirements (12). Athletes can also meet their protein

    needs on plant-based diets (13).

    n-3 Fatty Acids

    Whereas vegetarian diets are gener-ally rich in n-6 fatty acids, they maybe marginal in n-3 fatty acids. Dietsthat do not include fish, eggs, or gen-erous amounts of algae generally arelow in eicosapentaenoic acid (EPA)and docosahexaenoic acid (DHA),fatty acids important for cardiovascu-lar health as well as eye and brain

    development. The bioconversion of -linolenic acid (ALA), a plant-basedn-3 fatty acid, to EPA is generally lessthan 10% in humans; conversion of  ALA to DHA is substantially less (14). Vegetarians, and particularly vegans,tend to have lower blood levels of  EP A 

    and DHA than nonvegetarians (15).DHA supplements derived from mi-croalgae are well absorbed and posi-tively influence blood levels of DHA,and also   EPA through retroconver-sion (16). Soy milk and breakfastbars, fortified with DHA, are nowavailable in the marketplace.

    The Dietary Reference Intakes rec-ommend intakes of 1.6 and 1.1 g ALA per day, for men and women, respec-tively (17). These recommendationsmay not be optimal for vegetarianswho consume little if any DHA and

    EPA (17)   and thus may need addi-tional ALA for conversion to DHA andEPA. Conversion rates for ALA tendto improve when dietary   n-6   levelsare not high or excessive (14). Vege-tarians should include good sources of  ALA in their diet, such as flaxseed,walnuts, canola oil, and soy. Thosewith increased requirements of n-3fatty acids, such as pregnant and lac-tating women, may   benefit fromDHA-rich microalgae (18).

    Iron

    The iron in plant foods is nonhemeiron, which is sensitive to both inhibi-tors and enhancers of iron absorption.Inhibitors of iron absorption includephytates, calcium, and the polypheno-lics in tea, coffee, herb teas, and cocoa.Fiber only slightly inhibits iron absorp-tion (19). Some food preparation tech-niques such as soaking and sprouting beans, grains, and seeds, and the leav-ening of bread, can diminish phytatelevels (20) and thereby enhance ironabsorption (21,22). Other fermentationprocesses, such as those used to make

    miso and tempeh,   may also improveiron bioavailability (23). Vitamin C and other organic acids

    found in fruits and vegetables cansubstantially enhance iron absorp-tion and reduce the inhibitory effectsof phytate and thereby improve ironstatus (24,25). Because of lower bio-availability of iron from a vegetariandiet, the recommended iron intakesfor vegetarians are 1.8 times those of nonvegetarians (26).

    Whereas many studies of iron ab-

    sorption have been short term, thereis evidence that adaptation to low in-takes takes place over the long term,and involves both increased absorp-tion and decreased losses (27,28). In-cidence of iron-deficiency anemiaamong vegetarians is similar to that

    of nonvegetarians (12,29). Although vegetarian adults have lower ironstores than nonvegetarians, their se-rum ferritin levels are usually withinthe normal range (29,30).

    Zinc

    The bioavailability of zinc from vege-tarian diets is lower than from nonveg-etarian diets, mainly due to the higherphytic acid content of vegetarian diets(31). Thus, zinc requirements for some vegetarians whose diets consist mainly

    of phytate-rich unrefined grains and le-gumes may exceed the RecommendedDietary Allowance (26). Zinc intakes of  vegetarians vary with some researchshowing zinc intakes near recommen-dations (32) and other research finding zinc intakes of vegetarians signifi-cantly below recommendations (29,33).Overt zinc deficiency is not evident inWestern vegetarians. Due to the diffi-culty in evaluating marginal zinc sta-tus, it is not possible to determine thepossible effect of lower zinc absorptionfrom vegetarian diets (31). Zinc sourcesinclude soy products, legumes, grains,

    cheese, and nuts. Food preparationtechniques, such as soaking andsprouting beans, grains, and seeds aswell as leavening bread, can reducebinding of zinc by phytic acid and in-crease zinc bioavailability (34). Organicacids, such as citric acid, can also en-hance zinc absorption to some extent(34).

    Iodine

    Some studies suggest that veganswho do not consume key sources of 

    iodine, such as iodized salt or sea veg-etables, may be at risk for iodine de-ficiency, because plant-based   dietsare typically low in iodine (12,35). Seasalt and kosher salt are generally notiodized nor are salty seasonings suchas tamari. Iodine intake from sea veg-etables should be monitored becausethe iodine content of sea vegetables varies widely and some contain sub-stantial amounts of iodine (36).

    Foods such as soybeans, cruciferous vegetables, and sweet potatoes con-

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    tain natural goitrogens. These foodshave not been associated with thyroidinsufficiency in healthy people   pro- vided iodine intake is adequate (37).

    Calcium

    Calcium intakes of lacto-ovo-vegetar-ians are similar to, or   hig her than,those of nonvegetarians (12), whereasintakes of vegans tend to be lowerthan both groups and may fall belowrecommended intakes (12). In the Ox-ford component of the European Pro-spective Investigation into Cancerand Nutrition (EPIC-Oxford) study,the risk of bone fracture was similarfor lacto-ovo-vegetarians and meateaters, whereas vegans had a 30%higher risk of fracture possibly due totheir considerably lower mean cal-

    cium intake (38). Diets rich in meat,fish, dairy products, nuts, and grainsproduce a high renal acid load,mainly due to sulfate and phosphateresidues. Calcium resorption frombone helps to buffer this acid load,resulting in increased urinary lossesof calcium. A high sodium intake canalso promote urinary calcium losses.On the other hand, fruits and vegeta-bles rich in potassium and magne-sium produce a high renal alkalineload which slows bone calcium resorp-tion, and decreases calcium losses inthe urine. In addition, some studies

    show that the ratio of dietary calciumto protein is a better predictor of bonehealth than calcium intake alone.Typically, this ratio is high in lacto-ovo-vegetarian diets and favors bonehealth, whereas vegans have a ratioof calcium to protein that is similar toor lower than that of nonvegetarians(39). Many vegans may find it is eas-ier to meet their calcium needs if cal-cium-fortified foods or dietary supple-ments are utilized (39).

    Low-oxalate greens (eg, bok choy,broccoli, Chinese cabbage, collards,

    and kale) and fruit juices fortifiedwith calcium citrate malate are goodsources of highly bioavailable calcium(50% to 60% and 40% to 50%, respec-tively), while calcium-set tofu, andcow’s milk have good bioavailabilityof calcium (about 30% to 35%), andsesame seeds, almonds, and driedbeans have   a lower bioavailability(21% to 27%) (39). The bioavailabilityof calcium from soy milk fortified withcalcium carbonate is equivalent tocow’s milk although limited research

    has shown that calcium availability issubstantially less when tricalciumphosphate   is   used to fortify the soybeverage (40). Fortified foods such asfruit juices, soy milk, and rice milk,and breakfast cereals can contributesignificant amounts   of   dietary cal-

    cium for the vegan (41). Oxalates insome foods, such as spinach andSwiss chard, greatly reduce calciumabsorption, making these vegetablesa poor source of usable calcium. Foodsrich in phytate may also inhibit cal-cium absorption

    Vitamin D

     Vitamin D has long been known toplay a role in bone health. Vitamin Dstatus depends on sunlight exposureand intake of vitamin D–fortified

    foods or supplements. The extent of cutaneous vitamin D production fol-lowing sunlight exposure is highly variable and is dependent on a num-ber of factors, including the time of day, season, latitude, skin pigmenta-tion, sunscreen use, and age. Low vi-tamin D intakes (42), low serum 25-hydroxyvitamin D levels (12), andreduced bone mass (43) have been re-ported in some vegan and macrobioticgroups who did not use vitamin Dsupplements or fortified foods.

    Foods that are fortified with vita-min D include cow’s milk, some

    brands of soy milk, rice milk, and or-ange juice, and some breakfast cere-als and margarines. Both vitamin D-2and vitamin D-3 are used in supple-ments and to fortify foods. VitaminD-3 (cholecalciferol) is of animal ori-gin and is obtained through the ultra- violet irradiation of 7-dehydrocholes-terol from lanolin. Vitamin D-2(ergocalciferol) is produced from theultraviolet irradiation of ergosterolfrom yeast and is acceptable to veg-ans. Although some research sug-gests that vitamin D-2 is less effective

    than vitamin D-3 in maintaining se-rum 25-hydroxyvitamin D levels (44)other studies find that vitamin D-2and vitamin D-3 are equally effective(45). If sun exposure and intake of fortified foods are insufficient to meetneeds, vitamin D supplements arerecommended.

    Vitamin B-12

    The vitamin B-12 status of some veg-etarians is less than adequate due to

    not regularly consuming    reliablesources of vitamin B-12 (12,46,47).Lacto-ovo-vegetarians can obtain ad-equate vitamin B-12 from dairy foods,eggs, or other reliable vitamin B-12sources (fortified foods and supple-ments), if regularly consumed. For

     vegans, vitamin B-12 must be ob-tained from regular use of vitaminB-12-fortified foods, such as fortifiedsoy and rice beverages, some break-fast cereals and meat analogs, or RedStar Vegetarian Support Formula nu-tritional yeast; otherwise a daily vita-min B-12 supplement is needed. Nounfortified plant food contains anysignificant amount of active vitaminB-12. Fermented soy products cannotbe considered a reliable source of ac-tive B-12 (12,46).

     Vegetarian diets are typically rich

    in folacin, which may mask the hema-tological symptoms of vitamin B-12deficiency, so that vitamin B-12 defi-ciency may go undetected until afterneurological signs   and symptomsmay be manifest   (47). Vitamin B-12status is best determined by measur-ing serum levels of homocysteine,methylmalonic acid, or holotransco-balamin II (48).

    VEGETARIAN DIETS THROUGHOUT THELIFE CYCLE

    Well-planned vegan, lacto-vegetarian,and lacto-ovo-vegetarian diets are ap-propriate for all stages of the life cycle,including pregnancy and lactation. Ap-propriately planned vegan, lacto-vege-tarian, and lacto-ovo-vegetarian dietssatisfy nutrient needs of infants, chil-dren, and adolescents and promote nor-mal growth (49-51). Figure 1 providesspecific suggestions for meal planning for vegetarian diets. Lifelong vegetari-ans have adult height, weight, andBMIs that are similar to those who be-came vegetarian later in life, suggest-

    ing that well-planned vegetarian dietsin infancy and childhood do not affectfinal adult height or weight (53). Vege-tarian diets in childhood and adoles-cence can aid in the establishment of lifelong healthful eating patterns andcan offer some important nutritionaladvantages. Vegetarian children andadolescents have lower intakes of cho-lesterol, saturated fat, and total fat andhigher intakes of fruits, vegetables, andfiber than nonvegetarians (54,55). Veg-etarian children have also been re-

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    ported to be leaner and to have lowerserum cholesterol levels (50,56).

    Pregnant and Lactating Women

    The nutrient and energy needs of pregnant and lactating vegetarianwomen do not differ from those of nonvegetarian women with the excep-tion of higher iron recommendationsfor vegetarians. Vegetarian diets canbe planned to meet the nutrient needsof pregnant and lactating women. Ev-idence-based analysis of the researchliterature was used to evaluate exist-ing research on vegetarian pregnancy(57). Seven questions for evidence-analysis were identified:

    ●   How do macronutrient and energyintake in pregnant vegetarians dif-fer from intakes in pregnant omni- vores?

    ●   Are birth outcomes different formothers who maintain a vegetarian vs an omnivorous diet during preg-nancy?

    ●   How do macronutrient and energyintake in pregnant vegans differfrom intakes in pregnant omnivores?

    ●   Are birth outcomes different formothers who maintain a vegan vsan omnivorous diet during preg-nancy?

    ●   What are patterns of micronutrientintake among pregnant vegetarians?

    ●   What is the bioavailability of differ-ent micronutrients in pregnant veg-etarians?

    ●  What are birth outcomes associatedwith the micronutrient intake of maternal vegetarian diets?

    The complete results of this evidence-based analysis can be found on the EALWeb site (www.adaevidencelibrary.com)and are summarized below.

    Macronutrient and Energy Intake.   Fourprimary research studies were identi-fied that examined maternal macro-nutrient intake during lacto-ovo- orlacto- vegetarian pregnancy (58-61).

    None focused on pregnant vegans.EAL Conclusion Statement:  Limited re-

    search on non-US populations indi-cates that the macronutrient intakeof pregnant vegetarians is similar tothat of nonvegetarians with the fol-lowing exceptions (as percentages of energy intake):

    ●  pregnant vegetarians receive statis-tically lower levels of protein thanpregnant nonvegetarians; and

    ●  pregnant vegetarians receive statis-tically higher levels of carbohydrates

    than pregnant nonvegetarians.

    It is important to note, however,that none of the studies report a clin-ically significant difference in macro-nutrient intake. In other words, noneof the studies report a protein defi-ciency in pregnant vegetarians.Grade IIILimited.

    EAL Conclusion Statement:   No researchwas identified that focused on macro-nutrient intakes among pregnant veg-ans. Grade V Not Assignable.

    Birth Outcomes.   Four cohort studieswere identified that examined the rela-tionship between maternal macronu-trient intake during pregnancy andbirth outcomes such as birth weightand length (59-62). None of the studiesfocused on pregnant vegans.

    EAL Conclusion Statement:   Limited re-search on non-US populations indi-cates that there are no significanthealth differences in babies born tononvegan vegetarian mothers vs non- vegetarians.  Grade IIILimited.

    EAL Conclusion Statement:   No researchwas identified that focused on the birthoutcomes of vegan vs omnivorousmothers. Grade V Not Assignable.

    Micronutrient Intake.   Based on 10 stud-ies (58-60,63-69), two of which were

    conducted in the United States (64,65),only the following micronutrients hadlower intake among vegetarians thannonvegetarians:

    ●  vitamin B-12;●  vitamin C;●  calcium; and●   zinc.

     Vegetarians did not meet dietarystandard (in at least one country) for:

    ●  vitamin B-12 (in the United King-dom);

    ●   iron (in the United States, for both

     vegetarians and omnivores);●   folate (in Germany, though lower

    rate of deficiency than among omni- vores); and

    ●  zinc (in the United Kingdom).

    EAL Conclusion Statement:  Grade IIILimited.

    Micronutrient Bioavailability.   Six studies(five non-US, one with combined USand non-US samples; all but one of pos-itive quality) were identified that ex-amined the bioavailability of differentmicronutrients in vegetarian  vs non-

     vegetarian pregnant women (58,63,64,66,67,69). Of the micronutrients exam-ined in the research, only serum B-12levels were significantly lower in non- vegan-vegetarians than nonvegetar-ians. In addition, one study reportedthat lower B-12 levels are more likelyto be associated with high serum totalhomocysteine in lacto-ovo-vegetariansthan low meat eaters or omnivores.Whereas zinc levels were not signifi-cantly different between nonvegan- vegetarians and nonvegetarians, vege-tarians who have a high intake of 

    calcium may be at risk for zinc defi-ciency (because of the interaction be-tween phytate, calcium, and zinc).Based on limited evidence, plasma fo-late levels may actually be higheramong some vegetarian groups thannonvegetarians.

    EAL Conclusion Statement:  Grade IIILimited.

    Micronutrients and Birth Outcome EAL Con-clusion Statement:   Limited evidencefrom seven studies (all outside the

     A variety of menu planning approaches can provide adequat e nutrit ion for vegetarians.The Dietary Reference Intakes are a valuable resource for food and nutrition professionals.

     Various food guides (41,52) can be used when working with vegetarian clients. In addition, thefollowing guidelines can help vegetarians plan healthful diets:

    ●  Choose a variety of foods, including whole grains, vegetables, fruits, legumes, nuts, seeds,and, if desired, dairy products, and eggs.

    ●  Minimize intake of foods that are highly sweetened, high in sodium, and high in fat,especially saturated fat and  trans -fatty acids.

    ●  Choose a variety of fruits and vegetables.●   If animal foods such as dairy products and eggs are used, choose lower-fat dairy products

    and use both eggs and dairy products in moderation.●  Use a regular source of vitamin B-12 and, if sunlight exposure is limited, of vitamin D.

    Figure 1.   Suggestions for planning vegetarian meals.

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    United States) indicated that the mi-cronutrient content of a balanced ma-ternal vegetarian diet does not havedetrimental outcomes for the healthof the child at birth (58-63,69). Theremay be, however, a risk for a falsepositive diagnosis of Down syndrome

    in the fetus when maternal serumfree beta-human chorionic gonadotro-pin and alpha fetoprotein levels areused as markers in vegetarian moth-ers.  Grade IIILimited.

    Nutrition Considerations.   Results of evi-dence-based analysis suggest that vegetarian diets can be nutritionallyadequate in pregnancy and can leadto a positive birth outcome (57).

    Key nutrients in pregnancy include vitamin B-12, vitamin D, iron, andfolate whereas key nutrients in lacta-tion include vitamin B-12, vitamin D,

    calcium, and zinc. Diets of pregnantand lactating vegetarians should con-tain reliable sources of vitamin B-12daily. Based on recommendations forpregnancy and lactation, if there isconcern about vitamin D synthesisbecause of limited sunlight exposure,skin tone, season, or sunscreen use,pregnant and lactating women shoulduse vitamin D supplements or vita-min D–fortified foods. No studiesincluded in the evidence-analysis ex-amined vitamin D status during veg-etarian pregnancy. Iron supplements

    may be needed to prevent or treatiron-deficiency anemia, which is com-mon in pregnancy. Women capable of becoming pregnant as well as womenin the periconceptional period are ad- vised to consume 400   g folate dailyfrom supplements, fortified foods, orboth. Zinc and calcium needs can bemet through food or supplementsources as identified in earlier sec-tions on these nutrients.

    DHA also plays a role in pregnancyand lactation. Infants of vegetarianmothers appear to have lower cord

    and plasma DHA than do infants of nonvegetarians (70). Breast milkDHA is lower in vegans and lacto-ovo- vegetarians than in nonvegetarians(71). Because of DHA’s beneficial ef-fects on gestational length, infant vi-sual function, and neurodevelopment,pregnant and lactating vegetariansand vegans should choose foodsources of DHA (fortified foods or eggsfrom hens fed DHA-rich microalgae)or use a microalgae-derived DHA sup-plement (72,73). Supplementation

    with ALA, a DHA precursor, in preg-nancy and lactation has not beenshown to be effective in increasing in-fant DHA levels or breast milk DHA concentration (74,75).

    InfantsGrowth of young vegetarian infantsreceiving adequate amounts of breastmilk or commercial infant formula isnormal. When solid foods are intro-duced, provision of good sources of en-ergy and nutrients can ensure normalgrowth. The safety of extremely re-strictive diets such as fruitarian andraw foods diets has not been studiedin children. These diets can be verylow in energy, protein, some vita-mins, and some minerals and cannotbe recommended for infants and chil-

    dren.Breastfeeding is common in vege-tarian women, and this practiceshould be supported. The breast milkof vegetarian women is similar incomposition to that of nonvegetariansand is nutritionally adequate. Com-mercial infant formulas should beused if infants are not breastfed orare weaned before 1 year of age. Soyformula is the only option for non-breastfed vegan infants. Other prep-arations including soymik, rice milk,and homemade formulas should notbe used to replace breast milk or com-

    mercial infant formula.Solid foods should be introduced in

    the same progression as for nonveg-etarian infants, replacing strainedmeat with mashed or pureed tofu, le-gumes (pureed and strained if neces-sary), soy or dairy yogurt, cooked egg yolk, and cottage cheese. Later,around 7 to 10 months, foods such ascubed tofu, cheese, or soy cheese andbite-size pieces of veggie burgers canbe started. Commercial, full-fat, forti-fied soy milk or pasteurized cow’smilk can be used as a primary bever-

    age starting at age 1 year or older fora child who is growing normally andeating a variety of foods (51). Foodsthat are rich in energy and nutrientssuch as legume spreads, tofu, andmashed avocado should be used whenthe infant is being weaned. Dietaryfat should not be restricted in chil-dren younger than 2 years.

    Guidelines for dietary supplementsgenerally follow those for nonvegetar-ian infants. Breastfed infants whosemothers do not have an adequate in-

    take of vitamin B-12 should receive a vitamin B-12 supplement (51). Zincintake should be assessed and zincsupplements or zinc-fortified foodsused when complementary foods areintroduced if the diet is low in zinc ormainly consists of foods with low zinc

    bioavailability (76).

    Children

    Growth of lacto-ovo-vegetarian chil-dren is similar to that of their nonveg-etarian peers (50). Little informationabout the growth of nonmacrobiotic vegan children has been published.Some studies suggest that vegan chil-dren tend to be slightly smaller butwithin the normal ranges of the stan-dards for weight and height (58). Poorgrowth in children has primarily been

    seen in those on very restricteddiets (77).Frequent meals and snacks and the

    use of some refined foods (such as for-tified breakfast cereals, breads, andpasta) and foods higher in unsatur-ated fats can help vegetarian childrenmeet energy and nutrient needs. Av-erage protein intakes of vegetarianchildren (lacto-ovo, vegan, and macro-biotic) generally meet or exceed rec-ommendations (12). Vegan childrenmay have slightly higher proteinneeds because of differences in pro-tein digestibility and amino acid com-

    position (49,78)   but these proteinneeds are generally met when dietscontain adequate energy and a vari-ety of plant foods.

    Food guides for vegetarian childrenhave been published elsewhere (12).

    Adolescents

    Growth of lacto-ovo-vegetarian andnonvegetarian adolescents is similar(50). Earlier studies suggest that veg-etarian girls reach menarche slightlylater than nonvegetarians (79); more

    recent studies find no difference inage at menarche (53,80). Vegetarian diets appear to offer

    some nutritional advantages for ado-lescents. Vegetarian adolescents arereported to consume more fiber, iron,folate, vitamin A, and vitamin C thannonvegetarians (54,81). Vegetarianadolescents also consume more fruitsand vegetables, and fewer sweets,fast foods, and salty snacks comparedto nonvegetarian adolescents (54,55).Key nutrients of concern for adoles-

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    cent vegetarians include calcium, vi-tamin D, iron, zinc, and vitamin B-12.

    Being vegetarian does not causedisordered eating as some have sug-gested although a vegetarian dietmay be selected to camouflage an ex-isting eating disorder (82). Because of 

    this, vegetarian diets are somewhatmore common among adolescentswith eating disorders than in the gen-eral adolescent population (83). Foodand nutrition professionals should beaware of young clients who greatlylimit food choices and who exhibitsymptoms of eating disorders.

    With guidance in meal planning, vegetarian diets can be appropriateand healthful choices for adolescents.

    Older Adults

    With aging, energy needs decreasebut recommendations for several nu-trients, including calcium, vitamin D,and vitamin B-6 are higher. Intakesof micronutrients, especially calcium,zinc, iron, and vitamin B-12, declinein older adults (84). Studies indicatethat older vegetarians have dietaryintakes that are similar to nonveg-etarians (85,86).

    Older adults may have difficultywith vitamin B-12 absorption fromfood, frequently due to atrophic gas-tritis, so vitamin B-12-fortified foodsor supplements should be used be-

    cause the vitamin B-12 in fortifiedfoods and supplements is usuallywell-absorbed (87). Cutaneous vita-min D production decreases with ag-ing so that dietary or supplementalsources of vitamin D are especiallyimportant (88). Although current rec-ommendations for protein for healthyolder adults are the same as those foryounger adults on a body weight basis(17), this is a controversial area (89).Certainly older adults who have lowenergy requirements will need to con-sume concentrated sources of protein.

    Older adults can meet protein needson a vegetarian diet if a variety of protein-rich plant foods, including le-gumes and soy products, are eatendaily.

    Athletes

     Vegetarian diets can also meet theneeds of competitive athletes. Nutri-tion recommendations for vegetarianathletes should be formulated with con-sideration of the effects of both vegetar-

    ian diets and exercise. The position of  American Dietetic Association and Di-etitians of Canada on nutrition andathletic performance provides addi-tional information specific to vegetar-ian athletes (90). Research is needed onthe relation between vegetarian diet

    and performance. Vegetarian diets thatmeet energy needs and contain a vari-ety of plant-based protein foods, suchas soy products, other legumes, grains,nuts, and seeds, can provide adequateprotein without the use of special foodsor supplements (91). Vegetarian ath-letes may have lower muscle creatineconcentration due to low dietary creat-ine levels (92,93). Vegetarian athletesparticipating in short-term, high-inten-sity exercise and resistance training may benefit from creatine supplemen-tation (91). Some, but not all research

    suggests that amenorrhea may be morecommon among vegetarian  than non- vegetarian athletes (94,95). Female vegetarian athletes may benefit fromdiets that include adequate energy,higher levels of fat, and generousamounts of calcium and iron.

    VEGETARIAN DIETS AND CHRONICDISEASE

    Cardiovascular Disease (CVD)

    Evidence-based analysis of the re-search literature is being used toevaluate existing research on the re-

    lationship between vegetarian di-etary patterns and CVD risk factors(96). Two evidence analysis questionshave been completed:

    ●  What is the relationship between a vegetarian diet and ischemic heartdisease?

    ●   How is micronutrient intake in a vegetarian diet associated withCVD risk factors?

    Ischemic Heart   Disease.   Two large co-hort studies   (97,98)   and one meta-

    analysis (99)   found that vegetarianswere at lower risk of death from isch-emic heart disease than nonvegetar-ians. The lower risk of death was seenin both lacto-ovo-vegetarians and veg-ans (99). The difference in risk per-sisted after adjustment for BMI,smoking habits, and social class (97).This is especially significant becausethe lower BMI commonly seen in veg-etarians (99)   is one factor that mayhelp to explain the lower risk of heartdisease in vegetarians. If this differ-

    ence in risk persists even after adjust-ment for BMI, other aspects of a veg-etarian diet may be responsible forthe risk reduction, above and beyondthat which would be expected due tolower BMI.

    EAL Conclusion Statement:   A vegetar-

    ian diet is associated with a lower riskof death from ischemic heart disease.Grade IGood.

    Blood Lipid Levels.   The lower risk of death from ischemic heart diseaseseen in vegetarians could be ex-plained in part by differences in bloodlipid levels. Based on blood lipid lev-els in one large cohort study, the in-cidence of ischemic heart disease wasestimated to be 24% lower in lifelong  vegetarians and 57% lower in lifelong  vegans compared to meat eaters (97).

    Typically, studies find lower total cho-lesterol and low-density lipoprotein(LDL) cholesterol levels in vegetari-ans   (100,   for example). Interventionstudies have demonstrated a reduc-tion in total and LDL-cholesterol lev-els when subjects switched from theirusual diet to a vegetarian diet (101,for example). Although evidence islimited that a vegetarian diet is asso-ciated with higher high-density li-poprotein cholesterol levels or withhigher or lower triglyceride levels, a vegetarian diet is consistently associ-

    ated with lower LDL cholesterol lev-els. Other factors such as variationsin BMI and foods eaten or avoidedwithin the context of a vegetarian dietor lifestyle differences could partiallyexplain the inconsistent results withregard to blood lipid levels.

    Factors in a vegetarian diet thatcould have a beneficial effect on bloodlipid levels include the higher amountsof fiber, nuts, soy, and plant sterols andlower levels of saturated fat. Vegetari-ans consume between 50% and 100%more fiber than nonvegetarians and

     vegans have higher intakes than lacto-ovo-vegetarians (12). Soluble fiber hasbeen repeatedly shown to lower totaland LDL cholesterol levels and to re-duce risk of coronary heart disease (17). A diet high in nuts significantly lowerstotal and LDL cholesterol levels (102).Soy isoflavones may play a role in re-ducing LDL cholesterol levels and inreducing the susceptibility of LDL tooxidation (103). Plant sterols, found inlegumes, nuts and seeds, whole grains, vegetable oils, and other plant-based

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    foods reduce cholesterol absorption andlower LDL cholesterol levels (104).

    Factors Associated with Vegetarian Dietsthat May Affect Risk of CVD.   Other fac-tors in vegetarian diets may impactCVD risk independent of effects on

    cholesterol levels. Foods that featureprominently in a vegetarian diet thatmay offer protection from CVD in-clude soy protein (105), fruits and vegetables, whole grains, and nuts(106,107). Vegetarians appear to con-sume more phytochemicals than dononvegetarians because a greaterpercentage of their energy intakecomes from plant foods. Flavonoidsand other phytochemicals appear tohave protective effects as antioxi-dants, in reducing platelet aggrega-tion and blood clotting, as anti-in-flammatory agents, and in improving endothelial function (108,109). Lacto-ovo-vegetarians have been shown tohave significantly better vasodilationresponses, suggesting a beneficial ef-fect of vegetarian diet on vascular en-dothelial function (110).

    Evidence analysis was conductedto examine how the micronutrientmakeup of vegetarian diets might berelated to CVD risk factors.

    EAL Conclusion Statement:   No re-search meeting inclusion criteriawere identified that examined the mi-cronutrient intake of a vegetarian

    diet and CVD risk factors.   Grade V Not Assignable.

    Not all aspects of vegetarian dietsare associated with reduced risk forheart disease. The higher serum ho-mocysteine levels that have been re-ported in some vegetarians, appar-ently due to inadequate vitamin B-12intake, may increase risk of CVD(111,112)   although not all studiessupport this (113).

     Vegetarian diets have been suc-cessfully used in treatment of CVD. A regimen that used a very low-fat

    (10% of energy) near vegan (limitednonfat dairy and egg whites allowed)diet along with exercise, smoking ces-sation, and stress management, wasshown to reduce blood lipid levels,blood pressure, and weight,   and im-prove exercise capacity (114). A near- vegan diet high in phytosterols, vis-cous fiber, nuts, and soy protein hasbeen shown to be as effective as alow-saturated fat diet and a statin forlowering  serum LDL-cholesterol lev-els (115).

    Hypertension

     A cross-sectional study and a cohortstudy found that there was a lowerrate of hypertension among vegetari-ans than nonvegetarians (97,98).Similar findings were reported inSeventh-day   Adventists (Adventists)

    in Barbados (116) and in preliminaryresults from the A dventist HealthStudy-2 cohort (117). Vegans appearto have a lower rate of hypertensionthan do other vegetarians (97,117).

    Several studies have reportedlower blood pressure in vegetarianscompared to nonvegetarians (97,118)although other studies reported littledifference in blood pressure between vegetarians   and nonvegetarians(100,119,120). At least one of thestudies reporting lower blood pres-sure in vegetarians found that BMI

    rather than diet accounted for muchof the age-adjusted variation in bloodpressure (97). Vegetarians tend tohave   a lower BMI than nonvegetar-ians (99); thus, vegetarian diets’ in-fluence on BMI may partially accountfor reported differences in blood pres-sure between vegetarians and non- vegetarians. Variations in dietary in-take and lifestyle within groups of  vegetarians may limit the strength of conclusions with regard to the rela-tionship between vegetarian dietsand blood pressure.

    Possible factors in vegetarian dietsthat could result in lower blood pres-sure include the collective effect of  various beneficial compounds foundin plant foods such as potassium,magnesium, antioxidants, dietary fat,and fiber (118,121). Results from theDietary Approaches to Stop Hyper-tension study, in which subjects con-sumed a low-fat diet rich in fruits, vegetables and dairy, suggest thatsubstantial dietary levels of potas-sium, magnesium, and calcium playan important role in reducing bloodpressure levels (122). Fruit and vege-

    table intake was responsible for aboutone-half of the blood pressure reduc-tion of the Dietary Approaches toStop Hypertension diet (123). In ad-dition, nine studies report that con-sumption of five to 10 servings of fruitand vegetables   sig nificantly lowersblood pressure (124).

    Diabetes

     Adventist vegetarians are reported tohave lower rates of diabetes than Ad-

     ventist nonvegetarians (125). In the Adventist Health Study, age-adjustedrisk for developing diabetes was two-fold greater in nonvegetarians, com-pared with their vegetarian counter-parts (98). Although obesity increasesthe risk of type 2 diabetes, meat and

    processed meat intake was found tobe an important risk factor for diabe-tes e ven after adjustment for BMI(126). In the Women’s Health Study,the authors also observed positive as-sociations between intakes of redmeat and processed meat and risk of diabetes after adjusting for BMI, totalenergy intake, and exercise (127). A significantly increased risk of diabe-tes was most pronounced for frequentconsumption of processed meats suchas bacon and hot dogs. Results re-mained significant even after further

    adjustment for dietary fiber, magne-sium, fat, and glycemic load (128). Ina large cohort study, the relative riskfor type 2 diabetes in women for everyone-serving increase in intake was1.26 for red meat and 1.38 to 1.73 forprocessed meats (128).

    In addition, higher intakes of vege-tables, whole-grain foods, legumes,and nuts have all been associatedwith a substantially lower risk of in-sulin resistance and type 2 diabetes,and improved glycemic control in ei-ther normal or insulin-resistant indi- viduals (129-132). Observational

    studies have found that diets rich inwhole-grain foods are associated withimproved insulin sensitivity. This ef-fect may be partly mediated by signif-icant levels of magnesium and cerealfiber in the whole-grain foods (133).Persons with elevated blood glucosemay experience an improvement ininsulin resistance and lower fasting blood glucose levels after they haveconsumed whole grains (134). Peopleconsuming about three servings perday of whole-grain foods are 20% to30% less likely to develop type 2 dia-

    betes than low consumers (3 serv-ings per week) (135).In the Nurses’ Health Study, nut

    consumption was inversely associ-ated with risk of type 2 diabetes afteradjustment for BMI, physical activ-ity, and many other factors. The riskof diabetes for those consuming nutsfive or more times a week was 27%lower than those almost never eating nuts, whereas the risk of diabetes forthose consuming peanut butter atleast five times a week (equivalent to

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    5 oz peanuts/week) was 21% lowerthan those who almost never ate pea-nut butter (129).

    Because legumes contain slowly di-gested carbohydrate and have a highfiber content, they are expected to im-prove glycemic control and reduce in-

    cident diabetes. In a large prospectivestudy, an inverse association wasseen between the intake of total le-gumes, peanuts, soybeans, and otherlegumes by Chinese women, and theincidence of type 2 diabetes mellitus,after adjustment for BMI and otherfactors. The risk of type 2 diabeteswas 38% and 47% lower, for thoseconsuming a high intake of total le-gumes and soybeans, respectively,compared to a low intake (132).

    In a prospective study, the risk of type 2 diabetes was 28% lower for

    women in the upper quintile of vege-table, but not fruit intake, comparedto the lower quintile of vegetable in-take. Individual vegetable groupswere all inversely and significantlyassociated with the risk of type 2 di-abetes (131). In another study, con-sumption of green leafy vegetablesand fruit, but not fruit juice, was as-sociated with a lower risk of diabetes(136).

    Fiber-rich vegan diets are charac-terized by a low glycemic index  and  alow to moderate glycemic load (137).In a 5-month randomized clinical

    trial, a low-fat vegan diet was shownto considerably improve glycemic con-trol in persons with type 2 diabetes,with 43% of subjects reducing diabe-tes medication (138). Results weresuperior to those obtained from fol-lowing a diet based on American Dia-betes Association guidelines (individ-ualized based on body weight andlipid concentrations; 15%-20% pro-tein;  7% saturated fat; 60% to 70%carbohydrate and monounsaturatedfat; 200 mg cholesterol).

    Obesity

     Among Adventists, about 30% of whom follow a meatless diet, vegetar-ian eating patterns have been associ-ated with lower BMI, and BMI in-creased as the frequency of meatconsumption   increased in both menand women (98). In the Oxford Vege-tarian Study, BMI values were higherin nonvegetarians compared with vegetarians in all age groups for bothmen and women (139). In a cross-sec-

    tional study of 37,875 adults, meat-eaters had the highest age-adjustedmean BMI and vegans the lowest,with other vegetarians having inter-mediate values (140). In the EPIC-Oxford Study, weight gain over a5-year period, among a health-con-

    scious cohort, was lowest among those who moved to a diet containing fewer animal foods (141). In a largecross-sectional British study, it wasobserved that those people who be-came vegetarian as adults did not dif-fer in BMI or body weight comparedto those who were life-long vegetari-ans (53). However, those who havebeen following a vegetarian diet for atleast 5 years typically have a lowerBMI. Among Adventists in Barbados,the number of obese vegetarians, whohad followed the diet for more than 5

    years, was 70% less than the numberof obese omnivores whereas recent vegetarians (following the diet   5years) had   body weights similar toomnivores (116). A low-fat vegetariandiet has been shown to be more effec-tive in long-term weight loss for post-menopausal women than a moreconventional National   CholesterolEducation Program diet (142). Vege-tarians may have a lower BMI due totheir higher consumption of fiber-rich, low-energy foods, such as fruitand vegetables.

    Cancer

     Vegetarians tend to have an overallcancer rate lower than that of thegeneral population, and this is notconfined to smoking-related cancers.Data from the Adventist HealthStudy revealed that nonvegetarianshad a substantially increased risk forboth colorectal and prostate cancercompared with vegetarians, but therewere no significant differences in riskof lung, breast, uterine, or stomachcancer between the groups after con-

    trolling for age, sex, and smoking (98). Obesity is a significant factor in-creasing the risk of cancer at a num-ber of sites (143). Because the BMI of  vegetarians tends to be lower thanthat of nonvegetarians, the lighterbody weight of the vegetarians maybe an important factor.

     A vegetarian diet provides a varietyof cancer-protective dietary factors(144). Epidemiologic studies haveconsistently shown that a regularconsumption of fruit and vegetables is

    strongly associated   with a reducedrisk of some cancers (108,145,146). Incontrast, among survivors of earlystage breast cancer in the Women’sHealthy Eating and Living trial, theadoption of a diet enhanced by addi-tional daily fruit and vegetable serv-

    ings did not reduce additional breastcancer events   or   mortality over a7-year period (147).

    Fruit and vegetables contain a com-plex mixture of phytochemicals, pos-sessing potent antioxidant, antiprolif-erative, and cancer-protective activity.The phytochemicals can display addi-tive and synergistic effects, and arebest consumed in whole foods(148-150). These phytochemicals inter-fere with several cellular processes in- volved in the progression of cancer.These mechanisms include the inhibi-

    tion of cell proliferation, inhibition of DNA adduct formation, inhibition of phase 1 enzymes, inhibition of signaltransduction pathways and oncogeneexpression, induction of cell cycle arrestand apoptosis, induction of phase 2 en-zymes, blocking the activation of nu-clear factor-kappaB, and inhibiting an-giogenesis (149).

     According to the recent World Can-cer Research Fund report (143), fruitand vegetables are protective againstcancer of the lung, mouth, esophagus,and stomach, and to a lesser degreesome other sites. The regular use of 

    legumes also provides a measure of protection against stomach and pros-tate cancer (143). Fiber, vitamin C,carotenoids, flavonoids, and other phy-tochemicals in the diet are reported toexhibit protection against various can-cers. Allium vegetables may protectagainst stomach cancer and garlic pro-tects against colorectal cancer. Fruitsrich in the red pigment lycopene arereported to protect against prostatecancer (143). Recently, cohort studieshave suggested that a high intake of whole grains provided substantial pro-

    tection against various cancers (151).Regular physical activity provides sig-nificant protection against most of themajor cancers (143).

     Although there is such a variety of potent phytochemicals in fruit and vegetables, human population studieshave not shown large differences incancer incidence or mortality ratesbetween vegetarians and nonvegetar-ians (99,152). Perhaps more detailedfood consumption data are needed be-cause the bioavailability and potency

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    of phytochemicals depends on foodpreparation, such as whether the veg-etables are cooked or raw. In the caseof prostate cancer, a high dairy intakemay lessen the chemoprotective effectof a vegetarian diet. Use of dairy andother calcium-rich foods have been

    associated with an   increased risk of prostate cancer (143,153,154), al-though   not   all studies support thisfinding (155).

    Red meat and processed meat con-sumption is consistently associatedwith an increase in the risk of colorec-tal cancer (143). On the other hand,the intake of legumes was negativelyassociated with risk of colon cancer innonvegetarians (98). In a pooled anal-ysis of 14 cohort studies, the adjustedrisk of colon cancer was substantiallyreduced by a high intake of fruit and

     vegetable vs a low intake. Fruit and vegetable intakes were associatedwith a lower risk of distal colon can-cer, but not with proximal colon can-cer (156). Vegetarians have a sub-stantially greater intake of fiber thannonvegetarians. A high fiber intake isthought to protect against colon can-cer, although not all research sup-ports this. The EPIC study involving 10 European countries reported a25% reduction in risk of colorectalcancer in the highest quartile of di-etary fiber intake compared to thelowest. Based upon these findings,

    Bingham and colleagues (157)   con-cluded that in populations with a lowfiber intake, doubling the fiber intakecould reduce the colorectal cancer by40%. On the other hand, a pooledanalysis of 13 prospective cohortstudies reported a high dietary fiberintake was not associated with a de-creased risk of colorectal cancer afteraccounting for multiple risk factors(158).

    Soy isoflavones and soy foods havebeen shown to possess anti-cancerproperties. Meta-analysis of eight

    studies (one cohort, and seven casecontrol) conducted in high-soy-con-suming Asians showed a significanttrend of decreasing risk of breast can-cer with increasing soy food intake. Incontrast, soy intake was unrelated tobreast cancer risk in studies con-ducted in 11 low-soy-consuming Western populations (159). However,controversy remains regarding the value of soy as a cancer-protectiveagent, because not all research sup-ports the protective value of soy to-

    wards breast cancer (160). On theother hand, meat consumption hasbeen linked in some, but not all, stud-ies with an  increased risk of breastcancer (161). In one study, breast can-cer risk increased by 50% to 60% foreach additional 100 g/day of meat con-

    sumed (162).

    Osteoporosis

    Dairy products, green leafy vegeta-bles, and calcium-fortified plant foods(including some brands of ready-to-eat cereals, soy and rice beverages,and juices) can provide ample calciumfor vegetarians. Cross-sectional andlongitudinal population-based studiespublished during the past 2 decadessuggest no differences in bone min-eral density (BMD), for both trabecu-

    lar and cortical bone, between  omni- vores and lacto-ovo-vegetarians (163). Although very little data exist on

    the bone health of vegans, some stud-ies suggest that bone density is loweramong vegans compared with non- vegetarians (164,165). The Asian vegan women in these studies had very low intakes of protein and cal-cium. An inadequate protein and lowcalcium intake has been shown to beassociated with bone loss and frac-tures at the hip  and spine in elderlyadults (166,167). In addition, vitaminD status is compromised in some veg-

    ans (168).Results from the EPIC-Oxford study

    provide evidence that the risk of bonefractures for vegetarians is similar tothat of omnivores (38). The higher riskof bone fracture in vegans appeared tobe a consequence of a lower calciumintake. However, the fracture rates of the vegans who consumed over 525 mg calcium/day were not different f rom thefracture rates in omnivores (38). Otherfactors associated with a vegetariandiet, such as fruit and vegetable con-sumption, soy intake, and intake of vi-

    tamin K-rich leafy greens must be con-sidered when examining bone health.Bone has a protective role in main-

    taining systemic pH. Acidosis is seento suppress osteoblastic activity, withthe gene expression of specific matrixproteins and alkaline phosphatase ac-tivity diminished. Prostaglandin pro-duction by the osteoblasts increasessynthesis of the osteoblastic receptoractivator of nuclear factor kappaB li-gand. The acid induction of receptoractivator of nuclear factor kappaB li-

    gand stimulates osteoclastic activityand recruitment of new osteoclasts topromote bone resorption and buffer-ing of the proton load (169).

     An increased fruit and vegetableconsumption has a positive effect onthe calcium economy and markers of 

    bone metabolism (170). The high po-tassium and magnesium content of fruits, berries, and vegetables, withtheir alkaline ash, makes these foodsuseful dietary agents for inhibiting bone resorption (171). Femoral neckand lumbar spine BMD of premeno-pausal women was about 15% to 20%higher for women in the highest quar-tile of potassium intake comparedwith those in the lowest quartile(172).

    Dietary potassium, an indicator of net endogenous acid production and

    fruit and vegetable intake, was shownto exert a modest influence on mark-ers of bone health, which over a life-time may contribute to a decreasedrisk of osteoporosis (173).

    High protein intake, especially an-imal protein, can produce increasedcalciuria (167,174). Postmenopausalwomen with diets high in animal pro-tein and low in plant protein revealeda high rate of bone loss and a greatlyincreased risk of hip fracture (175). Although excessive protein intakemay compromise bone health, evi-dence exists that low protein intakes

    may increase the risk of low bone in-tegrity (176).

    Blood levels of undercarboxylatedosteocalcin, a sensitive marker of vi-tamin K status, are used to indicaterisk of hip fracture (177), and predictBMD (178). Results from two large,prospective cohort studies suggest aninverse relationship between vitaminK (and green, leafy vegetable) intakeand risk of hip fracture (179,180).

    Short-term clinical studies suggestthat soy protein rich in isoflavones de-creases spinal bone loss in postmeno-

    pausal women (181). In a meta-analy-sis of 10 randomized controlled trials,soy isoflavones demonstrated a signifi-cant benefit on spine BMD (182). In arandomized controlled trial, postmeno-pausal women receiving genistein ex-perienced significant decreases in uri-nary excretion of deoxypyridinoline (amarker of bone resorption), and in-creased levels of serum bone-specific al-kaline phosphatase (a marker of boneformation) (183). In another meta-anal-ysis of nine randomized controlled tri-

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    als on menopausal women, soy isofla- vones significantly inhibited boneresorption and stimulated bone forma-tion compared to placebo (184).

    To promote bone health, vegetari-ans should be encouraged to consumefoods that provide adequate intakes

    of calcium, vitamin D, vitamin K, po-tassium, and magnesium; adequate,but not excessive protein; and to in-clude generous amounts of fruits and vegetables and soy products, withminimal amounts of sodium.

    Renal Disease

    Long-term high intakes of dietaryprotein (above 0.6 g/kg/day for a per-son with kidney disease not undergo-ing dialysis or above the Dietary Ref-erence Intake for protein of 0.8 g/kg/ 

    day for people with normal kidneyfunction) from either animal or vege-tables sources, may worsen existing chronic kidney disease or cause renalinjury in   those with normal renalfunction (185). This may be due to thehigher glomerular filtration rate as-sociated with a higher protein intake.Soy-based vegan diets appear to benutritionally adequate for peoplewith chronic kidney disease and mayslow   progression of kidney disease(185).

    DementiaOne study suggests that vegetariansare at lower risk of developing demen-tia than nonvegetarians (186). Thisreduced risk may be due to the lowerblood pressure seen in vegetarians orto the higher antioxidant intake of  vegetarians (187). Other possible fac-tors reducing risk could include alower incidence of cerebrovasculardisease and possible reduced use of postmenopausal hormones. Vegetari-ans can, however, have risk factorsfor dementia. For example, poor vita-

    min B-12 status has been linked to anincreased risk of dementia apparentlydue to the hyperhomocysteinemiathat is seen with vitamin B-12 defi-ciency (188).

    Other Health Effects of Vegetarian Diets

    In a cohort study, middle-aged vege-tarians were found to be 50% lesslikely to have diverticulitis comparedwith nonvegetarians (189). Fiber wasconsidered to be the most important

    protective factor, whereas meat in-take may increase the risk of divertic-ulitis (190). In a cohort study of 800women aged 40 to 69 years, nonveg-etarians were more than twice aslikely as vegetarians to suffer fromgallstones (191), even after control-

    ling for obesity, sex, and aging. Sev-eral studies from a research group inFinland suggest that fasting, followedby a vegan diet, may be useful in thetreatment of rheumatoid arthritis(192).

    PROGRAMS AND AUDIENCES AFFECTED

    Special Supplemental Nutrition Programfor Women, Infants, and Children

    The Special Supplemental NutritionProgram for Women, Infants, andChildren is a federal grant program

    that serves pregnant, postpartum,and breastfeeding women; infants;and children up to age 5 years whoare documented as being at nutri-tional risk with family income belowfederal standards. This program pro- vides vouchers to purchase somefoods suitable for vegetarians includ-ing infant formula, iron-fortified in-fant cereal, vitamin C–rich fruit or vegetable juice, carrots, cow’s milk,cheese, eggs, iron-fortified ready-to-eat cereal, dried beans or peas, andpeanut butter. Recent changes to thisprogram promote the purchase of whole-grain breads and cereals, allowthe substitution of canned beans fordried beans, and provide vouchers forpurchasing fruits and vegetables(193). Soy-based beverages and cal-cium-set tofu that meet specificationscan be substituted for cow’s milk forwomen and for children with medicaldocumentation (193).

    Child Nutrition Programs

    The National School Lunch Programallows nonmeat protein products in-

    cluding certain soy products, cheese,eggs, cooked dried beans or peas, yo-gurt, peanut butter, other nut or seedbutters, peanuts, tree nuts, and seedsto be used (194). Meals served mustmeet the 2005 Dietary Guidelines for Americans and provide at least onethird of the Recommended Dietary Allowance for protein, vitamins A andC, iron, calcium, and energy. Schoolsare not required to make modifica-tions to meals based on food choices of a family or a child although they are

    permitted to provide substitute foodsfor children who are medically certi-fied as having a special dietary need(195). Some public schools regularlyfeature vegetarian choices, including  vegan, menu items and this seems tobe more common than in the past al-

    though many school food programsstill have limited options for vegetar-ians (196). Public schools are allowedto offer soy milk to children who bring a written statement from a parent orguardian identifying the student’sspecial dietary need. Soy milks mustmeet specified standards to be ap-proved as substitutes and schoolsmust pay for expenses   that   exceedfederal reimbursements (197).

    Feeding Programs for Elderly Adults

    The federal Elderly Nutrition Pro-gram distributes funds to states, ter-ritories, and tribal organizations for anational network of programs thatprovide congregate and home-deliv-ered meals (often known as Meals onWheels) for older Americans. Mealsare often provided by local Meals onWheels agencies. A 4-week set of veg-etarian menus has been developed foruse by the National Meals on WheelsFoundation (198). Similar menushave been adapted by individual pro-grams including New York City’s De-partment for the Aging which has

    preapproved a 4-week set of vegetar-ian menus (199).

    Corrections Facilities

    Court rulings in the United Stateshave granted prison inmates the rightto have vegetarian meals for certainreligious and medical reasons (200).In the federal prison system, vegetar-ian diets are only provided for in-mates who document that their diet isa part of an established religiouspractice (201). Following review and

    approval by the chaplaincy team, theinmate can participate in the Alterna-tive Diet Program either through self-selection from the main line that in-cludes a nonflesh option and access tothe salad/hot bar or through provisionof nationally recognized, religiouslycertified processed foods (202). If meals are served in prepared trays,local procedures are developed for theprovision of nonflesh foods (201). Inother prisons, the process for obtain-ing vegetarian meals and the type of 

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    meal available varies depending onwhere the prison is   located and thetype of prison (201). Although someprison systems provide meatless al-ternatives, others simply leave meatoff the inmate’s tray.

    Military/Armed Forces

    The US Army’s Combat Feeding Pro-gram, which oversees all food regula-tions, provides a choice of vegetarianmenus including vegetarian Meals,Ready-to-Eat (203,204).

    Other Institutions and Quantity FoodService Organizations

    Other institutions, including colleges,universities, hospitals, restaurants,and publicly funded museums and

    parks, offer varying amounts andtypes of vegetarian selections. Re-sources are available for vegetarianquantity food preparation.

    ROLES AND RESPONSIBILITIES OF FOODAND NUTRITION PROFESSIONALS

    Nutrition counseling can be highlybeneficial for vegetarian clients whomanifest specific health problems re-lated to poor dietary choices and for vegetarians with existing clinical con-ditions that require additional di-etary modifications (eg, diabetes, hy-

    perlipidemia, and kidney disease).Depending on the client’s knowledgelevel, nutrition counseling may beuseful for new vegetarians and for in-dividuals at various stages of the lifecycle including pregnancy, infancy,childhood, adolescence, and for the el-derly. Food and nutrition profession-als have an important role in provid-ing assistance in the planning of healthful vegetarian diets for thosewho express an interest in adopting  vegetarian diets or who already eat a vegetarian diet, and they should be

    able to give current accurate informa-tion about vegetarian nutrition. In-formation should be individualizeddepending on type of vegetarian diet,age of the client, food preparationskills, and activity level. It is impor-tant to listen to the client’s own de-scription of his or her diet to ascertainwhich foods can play   a role in mealplanning.   Figure 1   provides   mealplanning suggestions.  Figure 2   pro- vides a list of Web resources on vege-tarian diets.

    Qualified food and nutrition profes-sionals can help vegetarian clients inthe following ways:

    ●  Provide information about meeting requirements for vitamin B-12, cal-cium, vitamin D, zinc, iron, and n-3fatty acids because poorly planned vegetarian diets may sometimesfall short of these nutrients.

    ●   Give specific guidelines for plan-ning balanced lacto-ovo-vegetarianor vegan meals for all stages of the

    life cycle.●   Supply information about general

    measures for health promotion anddisease prevention.

    ●   Adapt guidelines for planning bal-anced lacto-ovo-vegetarian or veganmeals for clients with special dietaryneeds due to allergies or chronic dis-ease or other restrictions.

    ●  Be familiar with vegetarian optionsat local restaurants.

    ●  Provide ideas for planning optimal vegetarian meals while traveling.

    ●   Instruct clients about the prepara-tion and use of foods that frequentlyare part of vegetarian diets. Thegrowing selection of products aimedat vegetarians may make it impos-sible to be knowledgeable about allsuch products. However, practitio-

    ners working with vegetarian cli-ents should have a basic knowledgeof preparation, use, and nutrientcontent of a variety of grains,beans, soy products, meat analogs,and fortified foods.

    ●   Be familiar with local sources forpurchase of vegetarian foods. Insome communities, mail ordersources may be necessary.

    ●  Work with family members, partic-ularly the parents of vegetarianchildren, to help provide the bestpossible environment for meeting 

    nutrient needs on a vegetarian diet.●   If a practitioner is unfamiliar with

     vegetarian nutrition, he/she shouldassist the individual in finding someone who is qualified to advisethe client or should direct the clientto reliable resources.

    Qualified food and nutrition profes-sionals can also play key roles in ensur-ing that the needs of vegetarians aremet in foodservice operations, includ-ing child nutrition programs, feeding programs for the elderly, corrections fa-

    cilities, the military, colleges, universi-ties, and hospitals. This can be accom-plished through development of guidelines specifically addressing theneeds of vegetarians, creation and im-plementation of menus acceptable to vegetarians, and the evaluation of whether or not a program meets theneeds of its vegetarian participants.

    CONCLUSIONS

     Appropriately planned vegetarian dietshave been shown to be healthful, nutri-

    tionally adequate, and may be benefi-cial in the prevention and treatment of certain diseases. Vegetarian diets areappropriate for all stages of the life cy-cle. There are many reasons for the ris-ing interest in vegetarian diets. Thenumber of vegetarians in the UnitedStates is expected to increase during the next decade. Food and nutritionprofessionals can assist vegetarian cli-ents by providing current, accurate in-formation about vegetarian nutrition,foods, and resources.

    Vegetarian Nutrition Dietetic PracticeGrouphttp://vegetariannutrition.net

    Andrews University Nutrition Departmenthttp://www.vegetarian-nutrition.info

    Center for Nutrition Policy and Promotionhttp://www.mypyramid.gov/tips_resources/ vegetarian_diets.html

    Food and Nutrition Information Centerhttp://www.nal.usda.gov/fnic/pubs/bibs/gen/ vegetarian.pdf

    Mayo Clinichttp://www.mayoclinic.com/health/ vegetarian-diet/HQ01596

    Medline Plus, Vegetarian Diethttp://www.nlm.nih.gov/medlineplus/ vegetariandiet.html

    Seventh-day Adventist DieteticAssociationhttp://www.sdada.org/plant.htm

    The Vegan Society (vitamin B-12)http://www.vegansociety.com/food/nutrition/ b12/ 

    The Vegetarian Resource Grouphttp://www.vrg.org

    The Vegetarian Society of the UnitedKingdomhttp://www.vegsoc.org/health

    Figure 2.  Useful Web sites concerning vege-

    tarian diets.

    July 2009   ●   Journal of the AMERICAN DIETETIC ASSOCIATION   1277

    http://vegetariannutrition.net/http://www.vegetarian-nutrition.info/http://www.mypyramid.gov/tips_resources/vegetarian_diets.htmlhttp://www.mypyramid.gov/tips_resources/vegetarian_diets.htmlhttp://www.nal.usda.gov/fnic/pubs/bibs/gen/vegetarian.pdfhttp://www.nal.usda.gov/fnic/pubs/bibs/gen/vegetarian.pdfhttp://www.mayoclinic.com/health/vegetarian-diet/HQ01596http://www.mayoclinic.com/health/vegetarian-diet/HQ01596http://www.nlm.nih.gov/medlineplus/vegetariandiet.htmlhttp://www.nlm.nih.gov/medlineplus/vegetariandiet.htmlhttp://www.sdada.org/plant.htmhttp://www.vegansociety.com/food/nutrition/b12/http://www.vegansociety.com/food/nutrition/b12/http://www.vrg.org/http://www.vegsoc.org/healthhttp://www.vegsoc.org/healthhttp://www.vrg.org/http://www.vegansociety.com/food/nutrition/b12/http://www.vegansociety.com/food/nutrition/b12/http://www.sdada.org/plant.htmhttp://www.nlm.nih.gov/medlineplus/vegetariandiet.htmlhttp://www.nlm.nih.gov/medlineplus/vegetariandiet.htmlhttp://www.mayoclinic.com/health/vegetarian-diet/HQ01596http://www.mayoclinic.com/health/vegetarian-diet/HQ01596http://www.nal.usda.gov/fnic/pubs/bibs/gen/vegetarian.pdfhttp://www.nal.usda.gov/fnic/pubs/bibs/gen/vegetarian.pdfhttp://www.mypyramid.gov/tips_resources/vegetarian_diets.htmlhttp://www.mypyramid.gov/tips_resources/vegetarian_diets.htmlhttp://www.vegetarian-nutrition.info/http://vegetariannutrition.net/

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