Vitamins Fall 2011

8/2/2019 Vitamins Fall 2011

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Introduction

Vitamins were discovered at the beginningof the twentieth century.

Definition: An essential, noncaloric,

organic nutrient needed in tiny amounts inthe diet.


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Introduction

The role of vitamins is to help makepossible the processes by which othernutrients are digested, absorbed, andmetabolized or built into body structures.

The only disease a vitamin can cure is theone caused by a deficiency of that vitamin.


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Definition and Classification ofVitamins


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Vitamin Precursors

Some vitamins exist as precursors, orprovitamins


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Fat-Soluble and Water-Soluble Vitamins


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The Fat-Soluble Vitamins

A, D, E, K Found in fats and oils of foods

Require bile for absorption

Stored in liver and fatty tissues until needed

Not needed in the diet daily

Can reach toxic levels if too much is consumed

Deficiencies can occur when people eat dietsthat are extraordinarily low in fat


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Vitamin A

Beta-carotene plant-derived precursor

Retinol active form stored in the liver

Converted by cells into its other two active forms,

retinal and retinoic acid, as needed


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Vitamin A plays a role in Gene expression

Vision

Maintenance of body linings and skin Immune defenses

Growth of bones and of the body

Normal development of cells

Reproduction


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Regulation of Gene Expression

Vitamin A exerts influence on bodyfunctions through its regulation of genes.

Hundreds of genes are regulated by the

retinoic acid form of vitamin A.


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Food Sources of Vitamin A

Beta-carotene is found in vegetables andfruits

Orange or muddy green colored

Active vitamin A is found in foods of animalorigin

Liver, fish oil, milk, fortified cereals, eggs,

butter


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Food Sources of Vitamin A


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Vitamin D

Can be self-synthesized with the help ofsunlight.

Whether made with the help of sunlight or

obtained from food, vitamin D undergoeschemical transformations in the liver andkidneys to activate it.


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Roles of Vitamin D

Vitamin D functions as a hormoneto: Regulate blood calcium and phosphorus levels,

thereby maintaining bone integrity

To replenish blood calcium, vitamin D acts atthree body locations to raise blood calciumlevels:

Skeleton

Digestive tract

Kidneys


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Vitamin D stimulates maturation of cells,including immune cells that defend againstdisease

Vitamin D acts on genes, affecting how cells

grow, multiply, and specialize

Deficiencies may include

High blood pressure

Some common cancers

Rheumatoid arthritis

Multiple sclerosis

Psoriasis

Roles of Vitamin D


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How Can People Make a Vitamin from Sunlight?

When ultraviolet light from the sun shineson a cholesterol compound in human skin,the compound is transformed into a vitaminD precursor and is absorbed directly into

the blood.

Over the next day, the liver and kidneysfinish converting the precursor to active

vitamin D.

Sunlight presents no risk of vitamin Dtoxicity; sun breaks down excess vitamin D

in the skin.


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Intake Recommendations and Food Sources

5 micrograms/day for adults 19 to 50 years

UL 50 micrograms/day (2,000 IU on supplementlabels)


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Vitamin E

Vitamin E, tocopherol


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The Extraordinary Bodyguard

Vitamin E is an antioxidant.Oxidative damage occurs when highlyunstable molecules known as free radicals,

formed normally during cell metabolism,and disrupt cellular structures.


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Deficiencies are almost never seen inhealthy humans.

A classic vitamin E deficiency occurs in

premature babies born before the transferof the vitamin from mother to the infant,which takes place in the last weeks ofpregnancy.

Infants RBC lyse and infant becomes anemic

Vitamin E Deficiency


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Chronic Diseases and Vitamin E Intakes

Heart disease and cancer may arise in partthrough tissue oxidation and inflammation.

People with low blood vitamin E

concentrations die more often from theseand other causes than do people withhigher blood levels.

d S f i i


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Food Sources of Vitamin E

R l f Vit i K


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Roles of Vitamin K

Main function of vitamin K is to helpsynthesize proteins that help blood clot.

Also necessary for the synthesis of key boneproteins.

S f Vit i K


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Sources of Vitamin K

Vit i K T i it


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Vitamin K Toxicity

Toxicity is rare and there is no TolerableUpper Intake Level.

Toxicity causes jaundice and may occur ifsupplements of a synthetic version aregiven too enthusiastically.

Th W t S l bl Vit i


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The Water-Soluble Vitamins

Vitamin C and the B vitamins Cooking and washing cut foods with water can

leach these vitamins out of the food.

Absorbed easily and excreted easily in urine. Foods never deliver a toxic dose of them but

large doses concentrated in some vitaminsupplements can reach toxic levels.

The most expensive urine in town

Th W k f Vit i C


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The Work of Vitamin C

Functions of vitamin C Assists enzymes involved in the formation and

maintenance ofcollagen

Acts as an antioxidant, especially protecting theimmune system cells from free radicalsgenerated during their assault on invaders

Deficiency Symptoms


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Deficiency Symptoms

Most scurvy symptoms are due to collagenbreakdown

Loss of appetite

Growth cessation

Tenderness to touch

Bleeding gums

Swollen ankles and wrists

Anemia

Red spots on skin

Weakness

Loose teeth

Is Vitamin C Hazardous to Health?


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Possible adverse effects of taking 2 grams aday:

Alteration of the insulin response to carbohydrate

Interference with blood clotting medications

Kidney stones

Gout

Digestive upsets



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The Need for Vitamin C


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B vitamins function as part

ofcoenzymes

coenzymes help enzymesdo their jobs

B Vitamin Roles in Metabolism


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Thiamin, riboflavin, niacin, pantothenic acid,and biotin participate in the release ofenergy from the energy nutrients

Folate and vitamin B12

help cells multiply

Vitamin B6 helps the body use amino acidsto synthesize proteins


B Vitamin Deficiencies


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B Vitamin Deficiencies

In a B vitamin deficiency, every cell is affected.

Symptoms include

Nausea

Severe exhaustion

Irritability

Depression

Forgetfulness

Loss of appetite and weight

Impairment of immune response

Abnormal heart action

Skin problems

Swollen red tongue

Teary, red eyes

Pain in muscles

The B Vitamins as Individuals


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The B Vitamins as Individuals

Thiamin Plays a critical role in the energy metabolism of

all cells.

Occupies a site on nerve cell membranes.

Nerve processes and their responding musclesdepend heavily on thiamin.

Thiamin Deficiency


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Thiamin Deficiency

In developed countries today, alcohol abuseoften leads to a severe form of thiamindeficiency, Wernicke-Korsakoff syndrome.

Alcohol impairs thiamin absorption

Symptoms

Apathy, irritability, mental confusion, memory loss,jerky movement, staggering gait

Food Sources and Recommended Intakes


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Food Sources and Recommended Intakes

Rib fl i


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Riboflavin

Ni i


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Niacin

Participates in energy metabolism of everycell.

Deficiency disease is pellagra

Niacin


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Pellagra symptoms: 4 Ds

Diarrhea

Dermatitis

Dementia

Death

Niacin

Niacin Sources


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The key nutrient that prevents pellagra isniacin

Or, consuming adequate tryptophan whichcan be converted to niacin in the body

The amount of niacin in a diet is stated interms ofniacin equivalents (NE), ameasure that takes available tryptophan

into account

Niacin Sources


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Niacin as a Drug


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Supplements may be taken as a treatmentto lower blood lipids associated withcardiovascular disease.

Symptoms of toxicity

Life-threatening drop in blood pressure

Liver injury

Peptic ulcers

Vision loss

Niacin flush

g

Folate


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Folate helps synthesize DNA and so isimportant for making new cells

Folate Deficiency


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y

Deficiency of folate causes anemia,diminished immunity, and abnormaldigestive function.

Deficiencies are related to increased risk ofcervical cancer (in women infected withHPV), breast cancer (in women who drinkalcohol) and pancreatic cancer (in men who

smoke).

Folate and Birth Defects


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Adequate intakes of folate during pregnancycan reduce a womans chances of having achild with a neural tube defect (NTD).

NTD arise in the first days or weeks ofpregnancy, long before most womensuspect they are pregnant.

Sources of Folate and Recommendations


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Vitamin B12


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Vitamin B12

and folate are closely related:each depends on the other for activation.

Main roles: helps maintain nerves and is apart of coenzymes needed in new blood cellsynthesis.

Vitamin B12


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Symptoms of deficiency of either folate orvitamin B12 include the presence ofimmature red blood cells.

Administering extra folate often clears upthis blood condition but allows the B12deficiency to continue.

Vitamin B12s other functions then become

compromised, and the results can bedevastating: damaged nerves, creepingparalysis, and general muscle and nervemalfunctioning.

Vitamin B12


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Intrinsic factor is a compound made by thestomach needed for the absorption of B12.

A few people have an inherited defect in thegene for intrinsic factor, which makes B12absorption poor.

Vitamin B12


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Vitamin B12

must be injected to bypass thedefective absorptive system.

This anemia of the vitamin B12 deficiencycaused by a lack of intrinsic factor is knownas pernicious anemia.

Vitamin B12


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Vitamin B12


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Who is at particular risk of a B12 deficiency? Answer: vegans

Vitamin B6


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Biotin and Pantothenic Acid


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Biotin and pantothenic acid are alsoimportant in energy metabolism.

Both vitamins are readily available in foods.

Conclusion


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Conclusion


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Food Feature: Choosing Foods Rich inVi i


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Vitamins

Foods work in harmony to provide mostnutrients

A variety of foods works best

Controversy: Vitamin Supplements: Do theB fit O t i h th Ri k ?


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Benefits Outweigh the Risks?

Which is the best source?

Arguments in Favor of Taking Supplements


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People with Increased Nutrient Needs


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Nutrient needs increase during certainstages of life and so sometimes nutrientsupplementation is needed.

1. Women who lose a lot of blood and therefore a

lot of iron during menstruation each month mayneed an _______ supplement.

2. Newborns require a single dose of vitamin ___at birth.

3. Women of childbearing age need supplementsof _______ to reduce the risk of NTD.

Answers: 1. iron; 2. K; 3. folic acid

People with Low Nutrient Status


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Subclinical deficiencies are more commonthan classical deficiencies.

People who dont eat enough food to deliver theneeded amounts of nutrients, such as habitual

dieters, otherwise healthy elderly, andvegetarians who omit entire food groups andmay not find an appropriate substitute

People Coping with Physical Stress


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Any condition that interferes with a personsappetite, ability to eat, or ability to absorbor use nutrients can easily impair nutritionstatus.

Arguments Against Taking Supplements


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Unlike foods, supplements can easily causenutrient imbalances or toxicities.

The higher the dose, the greater the risk ofharm.

Arguments Against Taking Supplements


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Toxicity


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No one knows for sure how many people inthe U.S. suffer from supplement toxicitiesbut in the year 2005, over 125,000 adverseevents were reported from vitamins,

minerals, essential oils, herbs, and othersupplements.

Toxic overdoses are more common inchildren due to fruit-flavored, chewablevitamins shaped like cartoon characters thatyoung children like to eat in amounts thatcan cause poisoning.

Unknown Needs


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No one knows exactly how to formulate theideal supplement

Should phytochemicals be added? If yes, howmuch?

What nutrients should be added?

Absorption And Metabolism of Nutrients


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Nutrients are absorbed best when ingestedwith food.

Taken in pure, concentrated form, nutrientsare likely to interfere with one anothers

absorption or with the absorption ofnutrients from foods eaten with them.

Zinc hinders copper and calcium absorption

Iron hinders zinc absorption

Vitamin C enhances iron absorption

Marginal Deficiencies, Oxidative Stress, and Chronic Diseases


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g , ,

Antioxidant nutrients help to quench free radicals,

rendering them harmless to cellular structures.Population studies support the theory that peoplewith high intakes of fruits and vegetables thatsupply the antioxidant nutrients enjoy better health

than people with lower intakes.

Choosing a Type


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Conclusion


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People in developed nations are far more likely to

suffer from overnutrition and poor lifestyle choicesthan from nutrient deficiencies.

Invest energy in eating a wide variety of fruits andvegetables in generous quantities, along with therecommended daily amounts of whole grains, leanmeats, and milk products every day, and takesupplements only when they are needed.

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Vitamins Fall 2011

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