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Chapter 7

Lecture Slides

What are vitamins and how do they work?

Vitamins – Major Functions

Coenzyme Functions

B Vitamins

Coenzyme Functions

B Vitamins

Antioxidant Functions

Beta-Carotene (Vitamin A)

Vitamin C

Vitamin E

Free Radicals

• Reactive oxygen species (ROS)

– Superoxide radical

– Hydroxy radical

• Reactive nitrogen species (RNS)

– Interaction of nitric oxide (NO) with superoxide

• Free radicals are produced during normal metabolic processes and are involved in normal cell functioning, but may be produced in excess under certain circumstances and be damaging to cellular constituents

Figure 7.2

Coenzyme Functions

B vitamins

Antioxidant Functions

Beta-Carotene (Vitamin A)

Vitamin C

Vitamin E

Hormone Functions

Vitamin D

Essential vitamins

• Cannot be synthesized in the body in sufficient quantity

• Causes deficiency symptoms when intake is inadequate

• Alleviates deficiency symptoms when added back into the diet

• Some substances, such as CoQ10, have been attributed with vitamin-like activity, but are not essential vitamins

What vitamins are essential to human nutrition?

• Water-soluble vitamins

– Thiamin

– Riboflavin

– Niacin

– Vitamin B6

– Vitamin B12

– Folate

– Biotin

– Pantothenic acid

– Choline*

– Vitamin C

• Fat-soluble vitamins

– Vitamin A

– Vitamin D

– Vitamin E

– Vitamin K

* Not classified as a vitamin

Foods rich in VitaminsStarches

and Grains

Fruits, citrus and others

Vegetables, dark green and others

Meat, fish,

poultry

Milk and dairy

products

Fats and Oils

Folate

β-carotene

Niacin

Folate

Niacin

Folate

* Fortified milk

Notes: (1) Vitamin D is synthesized in the skin from sunlight (2) Vitamin K is

synthesized in the intestines by bacteria (3) β-carotene may be converted to

vitamin A (4) Some foods are fortified with up to 100% of the RDA for vitamins

and minerals.

Food Labels - Vitamins

• Vitamins A and C listed

– % of Daily Value

• Others may be listed

In general, how do deficiencies or excesses of vitamins influence health or physical performance?

• Four stages of vitamin deficiency

– Preliminary stage

– Biochemical deficiency stage

– Physiologic deficiency stage

– Clinically manifest deficiency stage

Example of stages of vitamin deficiency(Vitamin B12)

• Preliminary stage

– Individual switches to a vegan diet and avoids fortified foods

• Biochemical deficiency stage

– Serum levels of vitamin B12 decrease

• Physiologic deficiency stage

– General feelings of weakness occur

• Clinically manifest deficiency stage

– Pernicious anemia develops

Note: First 3 stages represent Subclinical Malnutrition

Excessive intake of vitamins

• RDA for some vitamins now being considered for health promotion

• Hypervitaminosis

– Not likely to occur from natural foods

– Most likely due to excessive intake • Vitamin supplements

• Fortified foods

• Combination of the two

– Vitamins begin to function as drugs

– UL has been established for 7 of the 13 essential vitamins

Format for vitamins

• Name; terms

• DRI

• Food sources

• Major functions

• Deficiency

– Health

– Performance

• Supplementation

– Health

– Performance

• Prudent recommendations

Fat-Soluble Vitamins

• Vitamins A, D, E, and K

• Soluble in fat, but not in water

• Found in foods with some fat content

• Several may be manufactured in the body

• Excessive intake of several may be toxic

Essential Fat-soluble Vitamins

Vitamin A

Name (synonyms):

– Retinol (preformed vitamin A)

– Provitamins; carotenoids such as beta-carotene

Dietary reference intakes (DRI):

– Retinol equivalents (RE) or retinal activity equivalents (RAE)

– 1 RAE = 1 mcg retinal or 12 mcg beta-carotene

– RDA = 900, 700 RAE or 3000, 2300 IU (1 RAE = 3.3 IU)

– UL = 3 mg/day, or 10,000 IU

– DV is 5000 IU (1/2 the UL)

Vitamin A

Good food sources:

– Vitamin A in animal foods; liver, butter, fortified milk

– Beta-carotene in dark-green, yellow-orange vegetables; some fruits

Major functions in humans:

– Maintenance of epithelial cells; Vision – night and

peripheral; bone development; immune system;

antioxidant

Vitamin A

Deficiency - effects on health:

– Night blindness; skin lesions; impaired growth; blindness from xerophthalmia (destruction of cornea)

Deficiency - effects on sport performance:

– Theoretical problems with impaired gluconeogenesis, synthesis of muscle protein, or night vision in sports, but no data are available to support these contentions

Vitamin A

Supplementation - effects on health (beneficial or detrimental):

– Not recommended unless under medical guidance;

– Hypervitaminosis A: weakness, nausea, headache, joint pain, skin peeling; may lead to bone loss; hip fractures; liver damage; in pregnancy excess A may be teratogenic

– Beta-carotene; harmless yellowing of skin in excess

– Note: Antioxidant effects on health covered later in chapter

Vitamin A

Supplementation - effects on sport (beneficial or detrimental):

– Little theoretical value; no beneficial effect

– Note: Antioxidant effects of beta-carotene on exercise performance and prevention of muscle tissue damage covered later in the chapter

Vitamin A

Prudent recommendations:

– Supplementation in excess not recommended; excesses of both vitamin A and beta-carotene (discussed later) may be harmful to one’s health.

Vitamin D (cholecalciferol)

Name, terms:

– Cholecalciferol (vitamin D3)

– Calcitriol – Physiologically active hormonal form

DRI (In the absence of adequate sunlight):

– AI = 5 mcg, or 200 IU (1 mcg = 40 IU)

– AI = 400-600 IU for older individuals

– DV = 400 IU (Twice the AI)

– UL = 2,000 IU

Vitamin D

Food sources

– Most foods contain no vitamin D

– Fatty fish (salmon, sardines) contain 200-500 IU in 3 oz

– Egg yolks contain about 25 IU

– Mushrooms, Shitake; 3 contain about 250 IU

– Fortified foods (milk; cereals) may contain 50-100% of RDA

Supplements

– D2, ergocalciferol; D3, cholecalciferol

• D3, cholecalciferol, is the recommended form

– Normally contain 200-600 IU

– Some contain 5,000 IU

Vitamin D

Exposure to sunshine– Swimsuit with no sunscreen

• 20,000 – 30,000IU in 30 minutes

– Hand, arm and face exposure • RDA with 10-20 minutes in the summer sun

– Need longer exposure time in the winter

• May be difficult to obtain sufficient amounts in northern latitudes

Vitamin D

• Major functions:

– Bone metabolism

• Works with parathormone (parathyroid gland)

• Absorb Ca++ from intestines and kidney

• Helps regulate phosphate metabolism

– Appears to be important in muscle function

– Involved in the development of the skin

– May help inhibit cell proliferation

Vitamin D

Deficiency – Health effects

– Some contend vitamin D deficiency is widespread and is associated with serious health problems

– Increased losses of calcium from bone

• Rickets in children; osteomalacia in adults

– Muscle weakness: impaired calcium metabolism in muscle

• Increased risk of falls in older individuals

– Relation of sun exposure to cancer development

• Epidemiological research shows risk of certain cancers with adequate exposure to sunshine; vitamin D may inhibit cell proliferation

Vitamin D

• Deficiency – Physical Performance– Although vitamin D deficiency may cause muscle

weakness, few data are available relative to the effects of vitamin D deficiency on exercise performance

Vitamin D

• Supplementation – Health effects

– Bone health

• Combined with calcium appears to help decrease fractures in postmenopausal women

• May also lower the risk of fractures in the elderly by increasing muscle strength and preventing falls

– Cancer

• Epidemiological studies show reduced risk of colorectal cancer with vitamin D and calcium intake

• Prospective studies are equivocal, but some find reduced cancer risk. Research is ongoing.

Vitamin D

– Diabetes

• May enhance immune functions to prevent autoimmune diseases

• Supplementation suggested to help prevent type I diabetes in children

Vitamin D

– Kidney stones and other adverse effects

• Excess calcium may combine with some salts, such as oxalates, to form kidney stones

• Excess calcium may lead to calcified plaque in arteries

• Excess vitamin D may cause vomiting, weight loss, and loss of muscle tone

Vitamin D

• Supplementation – Effects on exercise performance

– Research is very limited, only a few studies

• No ergogenic effects of single megadose

• No ergogenic effects of supplementation over the course of 2 years

– Little is known of the vitamin D status of athletes

Vitamin D

– Obtain at least the RDA for your age

• Foods rich in or fortified with vitamin D and adequate sunshine

– Some health professionals recommend 1,000 to 2,000 IU daily

• Supplement with vitamin D, preferably D3

• Canada recommends supplement for elderly over 50

• Take no more than 2,000 IU daily

• Consult physician if at risk for kidney stones

Vitamin E

Name, terms:

– RRR-alpha-tocopherol

• d-alpha-tocopherol (natural form)

• dl-alpha-tocopherol (synthetic form)

– RRR-gamma-tocopherol

DRI:– RDA = 15 mg RRR-alpha-tocopherol

– 1 mg = 1.5 IU

– DV = 30 IU

– UL = 1,000mg or 1,500 IU

Vitamin E

Food sources:

– Polyunsaturated vegetable oils; margarine

1 tablespoon contains 3-5 IU

– Fortified cereals; wheat germ oil

Fortified cereals contain 10-45 IU

– 1 tablespoon wheat germ oil contains 40 IU

Moderate amount in meats, dairy, fruits and vegetables

Vitamin E

Supplements:

– May contain natural or synthetic sources

– Synthetic form (dl-) not the same as natural form (d-)

– Need 40-50% more of synthetic to match natural source

Vitamin E

• The total function of vitamin E in human nutrition is unknown

– “A vitamin looking for a disease”

• Major function is to serve as an antioxidant

– Prevent oxidation of cell phospholipids

• Red blood cells

• LDL-cholesterol

– Prevent oxidation of vitamin A

Vitamin E

Deficiency – Health:

– Deficiency is rare

– May result from a genetic deficiency to absorb fat

– May result from very low fat diets

– Free radical damage could cause cancer, heart disease (oxidized LDL) or anemia

Deficiency – Physical Performance

– Anemia could impair performance; few data available

Vitamin E

• Supplementation – Effects on health

– Antioxidant effects theorized to help prevent heart disease and cancer

– Research findings discussed later with other antioxidants

Vitamin E

– Theorized to maintain integrity of RBC and O2

delivery by preventing RBC membrane oxidation

– Possible benefits

• Altitude (1-3 miles)

• High-smog areas

– No apparent ergogenic effect at sea level

– Antioxidant effect on muscle tissue damage later in chapter

Vitamin E

– Diets rich in vitamin E may be healthful

– Supplements taken for purported health benefits should be used with caution

– Supplements are not ergogenic for physically active individuals

Vitamin K

Name, terms:

– Vitamin K is the generic term for menadione (K3)

• Phylloquinone (K1) – plant form

• Menoquinone (K2) – animal form

– AI = 120 and 90 mcg/day for males and females

– DV = 80 mcg

– No UL

Vitamin K

Food sources:

– Plant foods: Vegetable oils; green leafy vegetables

• Main dietary source

• 3 oz spinach contain 380 mcg

– Animal foods: Meats and milk

• Lower concentrations

• 3 oz meat contain 1 mcg

Synthesis in body:

– Intestinal bacteria form menoquinone (MK)

Vitamin K

– Essential in two steps of the blood clotting process

– May enhance function of osteocalcin, a protein with an important role in bone formation

Vitamin K

Deficiency – Effects on health

– Uncommon, but may occur with antibiotics

– May cause impaired blood clotting; hemorrhage

Deficiency – Effects on exercise performance

– No data available

Vitamin K

Supplementation – Effects on Health:

• Emerging data of a beneficial role on bone health

– Pharmacological doses effective to enhance bone mineralization in patients with osteoporosis

– Supplements (K1) may help prevent bone loss, particularly when taken with vitamin D

• Effective dose of 150-250 mcg/day

Vitamin K

Supplementation – Effects on exercise performance

• No studies have evaluated the ergogenic effects of vitamin K supplementation

• One short-term study reported an increased index of bone formation markers in female athletes, but some of the subjects were vitamin-K deficient before the supplementation protocol

• A long-term study found no beneficial effects on bone loss in female endurance athletes

Vitamin K

– Individuals desiring to use vitamin K supplements should do so only under the guidance of a physician

– One-a-day supplements may contain 0 to 120 mcg

Water-soluble Vitamins

• Nine vitamins

– B complex (8 individual vitamins)

– Vitamin C

• Deficiency symptoms may be noted in 2-4 weeks for some B vitamins

– May impair energy production for exercise

Figure 7.3

Essential Water-soluble Vitamins

Thiamin

Name, terms:

– Vitamin B1

– Antiberiberi vitamin

– Antineuritic vitamin

– RDA = 0.5 mg per 1,000 Calories

– 1.2 mg/day males; 1.1 mg/day females

– UL – None

– DV = 1.5 mg

Thiamin

• Food sources:

– Widely distributed in plants and animal foods

– Whole wheat, pork

– Fortified cereals contain 100% of RDA

– Energy substrate coenzyme for carbohydrate

• Needed to convert pyruvate to acetyl-CoA

• Normal functioning of the nervous system

Thiamin

• Deficiency – Health:

– Symptoms may occur in several weeks

– Mental confusion; muscular weakness

– Beriberi: Damage to nervous system and heart

• Deficiency – Physical Performance

– Thiamin needs are increased with exercise and a high-carbohydrate diet

– Deficiency impairs endurance performance

• Deficiencies are rare

Thiamin

• Supplementation: Effects on health

– No benefits to well nourished individuals

– No UL has been established for thiamin

• Supplementation: Effects on exercise performance

– No beneficial effects on performance• World War II studies

– Recent study suggests reduced subjective complaints of fatigue following strenuous exercise; needs confirmation

– Thiamine derivatives, allithiamine: no ergogenic effects

Thiamin

• Prudent recommendations:

– Supplements not recommended

– Athletes should consume nutrient-dense foods

Riboflavin

• Name, terms:

• Vitamin B2

• DRI:

• RDA = 1.3 mg/day males; 1.1 mg/day females

• UL – None

• DV = 1.7 mg

Riboflavin

• Food sources:

– Widely distributed in plants and animal foods

– Milk, dairy products, whole wheat

– Needed for oxidative enzymes - flavoproteins

– Important for carbohydrate, fat and protein metabolism

– Healthy skin tissue

Riboflavin

• Deficiency : Effects on health

– Glossitis; skin cracks; dry skin

• Deficiency : Effects on exercise performance

– Deficiency could impair endurance capacity

– Athletes may need more than the RDA during training

• Deficiencies are rare

Riboflavin

• Supplementation: Effects on health

– Has no health benefits for well-nourished individuals

– No UL has been set for riboflavin

• Supplementation: Effects on exercise performance

– Only one reputable study conducted and reported no beneficial effects on performance

Riboflavin

– Athletes should consume nutrient-dense foods

Niacin

Name, terms:

– Nicotinic acid; nicotinamide; anti-pellagra vitamin

Niacin equivalents (NE)

– RDA = 16 NE adult males; 14 NE adult females

– 1 NE = 1 mg niacin or 60 mg tryptophan

– UL = 35 mg

– DV = 20 mg

Niacin

• Food sources:

– Foods with high protein content

– Meat, fish, poultry, whole grains, legumes

– Coenzymes for glycolysis and fat synthesis

• Nicotinamide adenine dinucleotide (NAD)

– Important for both aerobic and anaerobic energy

processes

Niacin

– Skin rashes, mental confusion, lack of energy, muscle weakness

– Pellagra: severe dermatitis, diarrhea, dementia

– Could impair aerobic and anaerobic endurance performance, but no research involving niacin alone has been conducted

Niacin

Supplementation – Effects on health

– Various forms

• Immediate release

• Sustained release

• Extended release

– May cause flushing, burning and tingling sensation

– High doses may improve serum lipid profile

• Reduce total and LDL-cholesterol and triglycerides

• Increase HDL-cholesterol

– Excess may cause liver damage

– Use only under medical care

Niacin

– Several studies report no ergogenic effect

• 10-mile run

• Prolonged cycling

– Not recommended

• May impair endurance performance by interfering with fat metabolism during exercise

– One study suggests niacin may be helpful as a means to dissipate body heat during exercise

Niacin

– Use for lipid lowering only under care of a physician

Vitamin B6

Name, terms:

– Pyridoxine, pyridoxal, pyridoxamine

– RDA = 1.3 mg/day age 19-50

– 1.7 and 1.5 for males and females > age 50

– UL = 100 mg/day

– DV = 2 mg

Vitamin B6

Food sources:

– Widely distributed in protein foods

– Meat, fish, poultry, whole grains

Major functions:

– Coenzyme for protein metabolism; 60 enzymes

• Tryptophan to niacin

• Formation of proteins, such as hemoglobin

– Neurotransmitter formation

– Glycogenolysis and gluconeogenesis

Vitamin B6

– May occur in those on low-protein diets

– Skin disorders, mouth sores, mental depression, anemia, epileptic-like seizures

– Could impair endurance performance

• Anemia

• Impaired carbohydrate metabolism

– Some suggest impairment in fine motor control sports

Vitamin B6

Supplementation – Effects on health

– May be useful in treatment of PMS symptoms

– May lower homocysteine

• Discussed later relative to CHD

– Prolonged excessive intake (> 100 mg) may cause neural damage

• Loss of sensation from limbs

• Impaired gait

Vitamin B6

– Physically active individuals may need 1.5 to 2.5 the current RDA to maintain good B6 status

– Research suggests supplementation does not affect performance positively or negatively

Vitamin B6

– Supplements not recommended for health or enhanced exercise performance

– Consume nutrient-dense foods

– Excess consumption over time may lead to adverse health effects

Vitamin B12

Name, terms:

– Cobalamin

– RDA = 2.4 mcg/day

• Over age 50 should obtain B12 from fortified foods or supplements

– UL = None

– DV = 6 mcg

Vitamin B12

• Food sources:

– Only found in animal foods; meat, fish, poultry, milk

– Vegans need fortified food source or supplement

– Found in fortified foods, such as breakfast cereals

Major functions:

– Part of coenzyme critical to formation of DNA; works with folate

– Red blood cell formation

– Formation of myelin sheath on nerve fibers

Vitamin B12

– Deficiency is rare

• Liver stores may last for years

– Elderly may experience inadequacies

• Decrease enzyme to release B12 from food

• Decrease in transport proteins in intestines

– Adverse health effects

• Anemia (pernicious)

• Neural damage; paralysis

• Birth defects

Vitamin B12

– Anemia could impair endurance performance

Vitamin B12

– May help treat pernicious anemia

– No apparent adverse effects of large doses

– No apparent effect on endurance performance

– Senior athletes should consume fortified cereals or take a supplement

Vitamin B12

– Supplementation not normally warranted

– Consumption of fortified foods or vitamin supplements may be recommended for vegans and older persons

Folate

• Name, terms:

– Folate (natural form)

– Folic acid (synthetic form)

– Folacin (collective term)

• DRI:

– Dietary folate equivalents (DFE)

– RDA = 400 DFE/day; 600 DFE in pregnancy

– 1 DFE = 1 mcg food folate

= 0.6 mcg in fortified foods (1 mcg = 1.7 DFE)

= 0.5 mcg in supplement (1 mcg = 2.0 DFE)

– UL = 1,000 mcg (1 mg) DFE/day

– DV = 400 mg

Folate

• Food sources:

– Green, leafy vegetables, like spinach

– Whole grains, legumes

– Fruits and vegetables

– Fortified grains (140 mcg/100 grams of food)

– Coenzyme critical to formation of DNA

– Needed during periods of rapid cell division

• Red blood cell formation

• Early pregnancy

– Involved in homocysteine metabolism

Folate

• Deficiency – Effects on health

–Deficiencies may occur

• Alcoholics

• Females on oral contraceptives

– Decreased absorption of folate

Folate

• Deficiency – Effects on health

– Impair DNA formation

• Pernicious anemia; increased homocysteine

• Increased risk of cancer

• Increased levels of homocysteine

– Associated with several vascular diseases, including CHD and stroke

– May be just a marker for disease

– Research is ongoing

• Increased risk of neural tube defects

Folate

• Deficiency – Effect on exercise performance

Folate

–May help prevent neural tube defects (NTD)

– Food fortification studies

• ↓ incidence of NTD up to 78%

–All women of childbearing age should obtain 400 mcg as folic acid, plus food folate

Folate

– Research findings equivocal relative to homocysteine and vascular disease

• A meta-analysis reported a reduced risk of first stroke by 18%

• Another meta-analysis found no effect on CHD or all-cause mortality in patients with heart disease

• AHA does not classify homocysteine as a risk factor

– A recent 10-year study suggested folic acid supplementation (1 mg/day for 10 years) may increase the risk of some forms of cancer

Folate

– Large doses of folic acid may mask a vitamin B12 deficiency

• Pernicious anemia will not develop, but damage to the myelin sheath will continue and may not be recognized until irreparable damage is done

Folate

• Supplementation – Effects on physical performance

– No apparent effect on endurance performance

– Folate supplementation may increase serum folate, but has no effect on hemoglobin, VO2max, or endurance running time

Folate

– All women in childbearing years should obtain 400 DFE/day from fortified foods and supplements, in addition to food folate

– Current advice suggests males and postmenopausal women might use caution so as not to take excessive folic acid through fortified foods and supplements

Pantothenic acid

• DRI

– AI = 5 mg

– DV = 10 mg

– UL = None listed

• Food sources

– Distributed widely in all natural animal and plant foods

– Major losses in highly processed foods

– An essential component of coenzyme A

– Acetyl CoA from carbohydrate, fat and protein

Pantothenic acid

• Deficiency – Health and exercise performance

– Deficiencies are very rare

– Experimentally induced deficiencies cause

• Fatigue

• Muscle cramping

• Impaired motor coordination

– A deficiency could impair energy metabolism if adequate acetyl CoA was not available

Pantothenic acid

• Supplementation – Health and exercise performance

– Current research indicates that supplementation with pantothenic acid has no ergogenic effect on various tests of aerobic endurance performance in runners and cyclists

Pantothenic acid

– A balanced diet should provide adequate pantothenic acid for the healthy, physically active individual

Biotin

• DRI

– AI = 30 mcg

– DV = 300 mcg

– UL = None listed

• Food sources

– Organ meats, egg yolk, legumes, green leafy vegetables

– Also synthesized in the intestines by bacteria

– Coenzyme for enzymes involved in protein metabolism

– Involved in gene expression

– Involved in gluconeogenesis

Biotin

• Deficiency – Health and exercise performance

– Deficiencies are rare, but may occur in diets rich in raw egg whites

– Symptoms may include

• Loss of appetite,

• Mental depression

• Muscle pain

– No studies relative to deficiency states in athletes

Biotin

• Supplementation – Health and exercise performance

– No evidence that biotin supplementation enhances health or exercise performance is available

– Supplements appear to be harmless, with no adverse effects up to 200 mg daily

Biotin

– Supplements are unnecessary for the physically active individual

Choline

• DRI:

– AI = 550 mg/day males; 425 mg/day females

– UL = 3.5 grams/day

– DV = None

• Sources:

– Animal foods as lecithin; plants as free choline

– Precursor for lecithin; formation of acetylcholine

Choline

– Deficiency is very rare

– Experimental deficiency: Fatty liver and liver damage

• Deficiency – Physical Performance

– Plasma levels reduced in marathon; no adverse effects noted

Choline

• Supplementation -- Health

– Not apparently beneficial, as deficiency is rare

– Excess may cause GI distress, low blood pressure

• Supplementation – Physical Performance

– Preliminary studies have shown supplementation will ↑ serum choline

– Preliminary field and laboratory studies found an ergogenic effect

– More recent studies reveal no ergogenic effect on endurance performance

Choline

– Supplementation not warranted

Vitamin B Complex

• Eight vitamins in the B complex

• Function together in energy metabolism important to exercise

Vitamin B Complex

• Deficiency – Health

– A deficiency would impair overall health status.

– The homocysteine issue

• Deficiency increases plasma homocysteine

• High levels of homocysteine may predict heart attacks and strokes

• May be a result of disease, not a cause

Vitamin B Complex

• Deficiency - Exercise performance

– A deficiency of 4-8 weeks could impair both exercise performance

– World War II starvation studies

– Netherlands studies created deficiency over 4 weeks

• Impaired aerobic and anaerobic performance

Vitamin Deficiency: Effect 3-weeks deficiency of B vitamins and

vitamin C

• Decreased aerobic energy production

• Decreased anaerobic energy production

• In general, correcting a vitamin deficiency associated with impaired performance will enhance subsequent performance

Vitamin B Complex

• Supplementation - Health

– In 2004, Consumers Union noted some evidence that vitamin B, especially folate and B6, could reduce blood pressure and stroke risk

– Experimental study, Vitamin Intervention for Stroke Prevention (VISP) • Lowered serum homocysteine

• No effect on stroke, coronary events, or death

– Meta-analysis• No effect on progression of atherosclerosis

– American Heart Association• Does not recommend widespread use of vitamin B to reduce the

risk of heart attack or stroke

Vitamin B Complex

• Supplementation – Exercise performance

– Sport nutritionists recommend adequate vitamin B• Metabolic pathways using vitamin B may be stressed

• Adaptations to training increase requirements

• Strenuous exercise may increase turnover in sweat

• May be needed in the repair of muscle tissue

– B supplementation may be recommended to athletes in high energy expenditure sports who do not consume a nutrient-dense diet

– Some research reports B1, B6, B12 supplementation improves pistol shooing; needs confirming research

Vitamin B Complex

– Consume a balanced diet with natural, wholesome foods

– Fortified cereals provide substantial amounts of the B vitamins

– Women of childbearing age should obtain adequate folate and folic acid

– Athletes who train intensely for endurance sports and eat mainly highly processed foods should consider a B vitamin supplement

Vitamin C

• Name, terms:

– Ascorbic acid

• DRI:

– RDA = 90 mg/day males; 75 mg/day females

– UL = 2,000 mg/day

– DV = 60 mg

• Sources:

– Fruits and vegetables; citrus fruits

– One orange or glass of orange juice contains the RDA

Vitamin C

– Synthesis of collagen

– Formation of hormones and neurotransmitters;

– Helps absorb iron (non-heme iron)

– RBC formation

– Functions as an antioxidant

Vitamin C

– Rare in industrialized societies

– Smoking, aspirin, oral contraceptives increase need

– Major deficiency disease is scurvy• Bleeding gums

• Weakness

• Muscle cramps

• Impaired wound healing

• Anemia

– Epidemiological research• Higher incidence of CHD and cancer

Vitamin C

• Deficiency – Exercise performance:

– Weakness could impair exercise performance

– World War II starvation studies

• Minnesota starvation studies: Ancel Keys

Vitamin C

• Supplementation -- Health

– Antioxidant effects discussed later

– Controversial opinions on safety of megadoses

• Undesirable side effects– Diarrhea

– ↓ bioavailability of B6, B12, copper

– ↑ urinary calcium oxalates (short-term studies with 1,000 mg)

» Possible kidney stones

– Iron storage; oxidative effect of iron

– Rebound scurvy

• No adverse side effects– Excess amounts are excreted by the kidneys

– Long term study shows no increase in kidney stones

Vitamin C

• Supplementation – Exercise performance

– Antioxidant effects discussed later

– Early research indicates improvement in individuals who are vitamin-C deficient

– Some studies indicate reduced severity of upper respiratory tract infections (URTI) following ultraendurance exercise

– Current research shows no benefit to immune system functions after endurance exercise

– No apparent effect on exercise performance

Vitamin C

• Prudent recommendations;

– Obtain vitamin C naturally through foods

• Eat more fruits and vegetables

– May maintain plasma saturation with 200 mg/day

Vitamin Supplements:Ergogenic Aspects

• Many athletes use vitamin supplements

• Dietary supplements are marketed to physically-active individuals – Individual vitamins

– Multivitamins

– Antioxidants

– Vitamin-like substances

Should physically active individuals take vitamin supplements?

• Some possible reasons

– Weight-control sports

– Poor dietary habits

– Pregnancy

– Elderly, senior athletes

– Consult with your health professional

Can the antioxidant vitamins prevent fatigue or muscle damage during training?

• Exercise training may increase total antioxidant capacity– Superoxide dismutase

– Glutathione peroxidase

• Such adaptations provide protection against free radical damage

• Antioxidants not shown to improve exercise performance– Individual antioxidants

– Antioxidant cocktails

Antioxidants:Muscle damage during training

• Strenuous exercise may generate ROS to overwhelm the body’ natural antioxidant defense system

• Equivocal research and review findings relative to the effects of antioxidant supplementation– Some studies show reduction in markers of muscle tissue damage

– Other studies show no benefits

– Several studies found adverse effects of supplements

– Some suggest older athletes may benefit

• Most scientists recommend– More research is needed

– Athletes obtain antioxidant from natural foods

Antioxidant VitaminsMuscle Tissue Damage – Key Reviews

• Several antioxidants, vitamin C and, especially vitamin E, have been shown to decrease the exercise-induced increase in the rate of lipid peroxidation. Trained athletes who received antioxidant supplements have shown evidence of reduced oxidative stress, , which could help prevent muscle tissue damage.

• Aging lessens the exercise training-induced improvement in natural antioxidant enzymes and one prominent sports scientist suggests exercise training in older athletes might be assisted with antioxidant supplementation in attempts to optimize antioxidant defense.

• Whether the body’s own natural antioxidant defense system is sufficient to combat oxidative stress during prolonged exercise or whether antioxidant supplements are needed is unknown. More evidence is needed to support a recommendation for antioxidant supplements for those engaged in prolonged aerobic exercise.

Antioxidant Vitamins• Although some studies have indicated that supplementation

with vitamin E and vitamin C may decrease exercise-induced oxidative stress to muscle cells in humans, little evidence shows that antioxidant supplementation can improve human performance

How effective are the special supplements marketed for athletes?

• Multivitamin-mineral supplements

• Bee pollen

• CoQ10

• Quercetin

Multivitamin-mineral supplements

• Multivitamin-mineral supplementation (100-6000% of the RDA) has not been shown to enhance VO2max and aerobic capacity, as well as laboratory and field tests of anaerobic and aerobic endurance, such as 400-meter and 15K run performance, in elite athletes.

• Some athletes may be advise to take a simple one-a-day multivitamin-mineral

Bee pollen

• Marketed specifically to runners

– No specific physiological mechanism

– Not effective as ergogenic aid

– May cause allergic reaction

• Coenzyme Q10 (CoQ10)

– A lipid with characteristics of a vitamin

– Involved in oxidative processes; serves as an antioxidant

– Used in treatment of cardiovascular disease

– Use as an as ergogenic aid

• Studies cited in a book show ergogenic effects

• Well-controlled studies show no effects– VO2max

– Exercise time to exhaustion

– Muscle tissue damage

– May cause muscle tissue damage; prooxidant

Quercetin

• A dietary flavonol

• Functions as an antioxidant

• Marketed in some energy drinks

• Studied for effects on immune function in exercise

– Findings equivocal

• Research relative to ergogenic effects is limited

– Results not sufficient to support an ergogenic effect

• Additional research merited

What’s the bottom line regarding vitamin supplements for athletes?

• Some athletes may need supplements

• Some health professionals recommend a

one-a-day multivitamin-mineral

Vitamin Supplementation: Key Points

• A vitamin deficiency can impair physical performance• Correcting a vitamin deficiency returns performance to

normal• In general, supplementation to an athlete on a well-balanced

diet does not enhance performance• Obtaining adequate amounts of the antioxidant vitamins via a

healthful diet may benefit some athletes– Additional research appears to be warranted:

• Vitamin E and endurance at high altitude• Antioxidants and prevention of muscle catabolism; older athletes

• Some endurance athletes may need vitamin supplements– Weight-loss dieting– Females of childbearing age– Older athletes– Vegans who do not consume fortified foods (B12)– Poor dietary habits

Vitamin Supplements:Health Aspects

• Vitamin supplements

– Most popular of all dietary supplements

– Multibillion dollar industry

Can I obtain the vitamins I needthrough my diet?

• Vitamin intake may be inadequate for various reasons

– Food refining process may remove vitamins

• Food processing may help or hurt

– Improper home storage or preparation of foods

• Key point

– Consume a balanced diet of natural foods with high nutrient density

– Obtain your vitamins from foods

• Athletes in particular

Why are vitamin supplements often recommended?

• May be important for some individuals, including athletes, to consume supplements or fortified foods

– Women who are pregnant or lactating

– Individuals with certain diseases or disorders

– Individuals taking certain drugs

– Elderly individuals, who have higher RDA or AI

– Vegans who consume no vitamin B12

– Individuals on weight-loss diets

– Athletes who do not consume enough energy

– Individuals intolerant to certain foods

– Individuals who make unwise food selections

Why do individuals take vitamin overdoses?

• Vitamins marketed for health reasons

• Some use vitamins as drugs

Do foods rich in vitamins, particularly antioxidant vitamins, help deter chronic

diseases?• Epidemiological studies support the viewpoint that diets rich

in fruits, vegetables, whole grains and other plant foods may exert protective health effects– Heart disease

– Various cancers

• Such diets are rich in vitamins, including antioxidant vitamins, and other phytonutrients

• Underlying mechanism not known– Protective effect of antioxidants on immune functions

– Phytochemicals block tumor formation

Do vitamin supplements help deter disease?

• Many studies were epidemiological in nature

• More recent experimental studies with some disease processes

• NIH State-of-the-Science conference on vitamin and mineral supplements and health in 2006; analyzed only randomized controlled trials (RCTs)

– Cardiovascular disease and stroke

– Cancer

– Eye health

– Mental health

– General health

Cardiovascular disease and stroke

• Theories

– Vitamin E can prevent oxidation of LDL-cholesterol

– Antioxidants may exert anti-inflammatory effects

– B vitamins decrease homocysteine

• Most supportive evidence was epidemiological

• RCTs

– Do not support beneficial effect of antioxidants or B vitamins

– Some studies have shown increased risk of CHD and mortality

Cardiovascular disease and stroke

• Criticism of RCTs

– Done with CHD patients, not healthy individuals

– Vitamin E studies used mainly alpha-tocopherol, not the gamma form, which may lower serum cholesterol

• American Heart Association

– Does not recommend B vitamin supplementation to prevent CHD or stroke

– Recommends against antioxidant supplements

Cancer

• Theories

– Preventing DNA damage

– Strengthen immune system

• Epidemiological studies are inconsistent against various forms of cancer

Cancer

• Recent major reviews

– NIH State-of-the-Science Report and the American Institute of Cancer Research report on Nutrition and Prevention of Cancer

• NIH - Effects of vitamin/mineral supplements on cancer are inconsistent and data are insufficient to recommend for or against multivitamin use

• AICR - May be increased risk of some cancers with supplements. Does not recommend vitamin supplements for cancer prevention

• Recent Selenium and Vitamin E Cancer Trial (SELECT)

– Stopped early; increased risk of prostate cancer

Eye health

• Theories

– Prevent oxidation, a contributing factor to cataracts and Age Related Macular Degeneration (ARMD)

• NIH review indicates results are inconsistent, but one well designed study (AREDS) supports beneficial effects

– Vitamins C, E, beta-carotene; zinc and copper

– Consumers Union recommends use of a vitamin/mineral supplement for those in the intermediate stage of ARMD

• Some antioxidant phytonutrients now under study

Mental health

• Theory

– Brain cells susceptible to oxidative damage

– Vitamin E may prevent vascular damage caused by peptides

• Research findings

– Epidemiological research supports some beneficial effects of vitamin E from supplements and food

– Results from RCTs are inconsistent

– May delay onset of Alzheimer’s

• More research necessary

General health

• NIH report

– The present evidence is insufficient to recommend either for or against the use of multivitamins/minerals by the American public to prevent chronic disease

– Need advanced research

• Large-scale, long-term studies

How much of a vitamin supplement is too much?

• The Tolerable Upper Intake Level (UL)

• Set for 7 vitamins and choline

– Fat-soluble vitamins A, D, E

– Water-soluble vitamins niacin, folate, B6, C

• Not usually dangerous when consumed as natural foods

How much of a vitamin supplement is too much?

• Excessive intake may occur with supplements and fortified foods

– 20 milligrams of niacin in some breakfast cereals

– More than 50% the UL for adults

• Excessive vitamins in the body

– May be excreted in the urine

– May be stored in some body tissue

– May function in uncharacteristic ways

• Example: Teratogenic effects of excess vitamin A

Vitamin SupplementsA Current Recommendation

“Most people do not consume an optimal amount of all vitamins by diet alone . . . It appears prudent for all adults to take vitamin supplements.”

JAMA, 2002

The typical one-a-day multivitamin/multimineral

tablet may be sufficient.

If I want to take a vitamin-mineral supplement, what are some prudent guidelines?

• Most health professionals recommend against single vitamins

• A basic one-a-day multivitamin/mineral tablet may be recommended

• The ADA recommends low levels that do not exceed the RDA or AI

Vitamin/mineral supplements

• Check the Daily Value; look for 100% of DV

• Buy the inexpensive house brand, but be leery of some bargain brands, such as those in dollar stores

• Stick with the basics; 11 vitamins and 7 minerals

• Vitamin A

– Buy a supplement low in vitamin A, no more than 3,000 IU of retinol

– Select those with beta-carotene

• Vitamin D

– Select one with 400-600 IU if elderly, a vegan, or postmenopausal and do not obtain enough in the diet

– Select vitamin D3 which is more effective than D2

• Vitamin E

– Buy at least the DV, or 30 IU

– Doses of 100-200 IU appear to cause no risk

– Avoid doses higher than 400 IU

• Vitamin K

– Buy a supplement with K

– Not all supplements contain vitamin K

– The AI is 120 mcg, but DV is only 80 mcg

• B vitamins

– Buy a supplement that contains 100 percent of thiamin, riboflavin, niacin, folic acid, B6 and B12.

– You can ignore biotin and pantothenic acid

– Senior citizens should buy a supplement with 25 mcg

• Vitamin C

– Buy a supplement with 100-200 percent of the DV

– RDA is 90 and 75 mg, but DV is only 60 mg

• Calcium

– Buy a supplement with calcium if you are female or elderly and do not obtain adequate amounts in the diet

– Most supplements contain 200-300 mg

• Iron, copper, zinc

– Buy a supplement limited in these minerals, with no more than 100 percent of the RDA for each

– Iron DV is 18 mg, but male and postmenopausal female RDA is only 8 mg

• Magnesium and phosphorus

– Buy a supplement containing no more than 100 mg of magnesium and limited in phosphorus

• Chromium and selenium

– Buy a supplement containing 100 percent of the AI for chromium and RDA for selenium

Vitamin and mineral supplementation

• Think food first!

• Foods contain numerous phytonutrients in addition to vitamins and minerals

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