Vitamins & Minerals

Chapter 9

Vitamins

• Organic compounds that are essential for the optimal functioning of many different physiological processes in the body

• Major Functions– Coenzymes– Hormones– Neurotransmitters– Antioxidants

Vitamin Categories

• Water Soluble– Vitamin C– B-Vitamins (thiamin, riboflavin, niacin, B6, B12,

folic acid, pantothenic acid, biotin)

• Fat Soluble – Vitamin A (Retinol or beta carotene)– Vitamin D (calciferol)– Vitamin E (-tocopherol)– Vitamin K (menaquinone)

Exercise and Vitamin Requirements

• Inadequate vitamin status impairs performance

• Dies exercise increase vitamin requirement– Decreased absorption?– Loss in sweat?– Increased mitochondrial density?– Muscle hypertrophy?– Anti-oxidant requirement?

Athletes at Risk

• Low energy intake– Females– Gymnasts, dancers, wrestlers

• Unbalanced diet

Vitamin Supplementation Above the DRI or RDA

• Vitamin B6 may improve aerobic power

• Vitamin C may enhance heat acclimatization

• Vitamin E may enhance aerobic power at altitude

• B-complex vitamins may increase short term performance/recovery in hot climates

Antioxidants & Free Radicals

• Oxygen Free Radicals – Molecules with an unpaired electron in their

outer orbit– Produced by the reduction of molecular

oxygen, and ongoing process during normal cellular respiration

– Examples are superoxide (O2-), hydrogen

peroxide (H2O2), and hydroxyl radical (OH-)– Between 2-5% of the total electron flux during

normal metabolism generate free radicals

Consequences of Free Radicals

• Deterioration of membrane lipids

• Changes in membrane protein structure

• Mitochondria appear to be most susceptible to free radical damage

• Free radical damage has been implicated in diseases such as heart disease, cancer, diabetes, immune dysfunction, accelerated aging

Exercise and Free Radicals

• Increase in cellular respiration increases FR production

• Increase in body temperature increases rate of FR formation

• Increase in catecholamines increases FR formation

Natural Defenses Against Free Radicals

• Protective antioxidant enzymes

• Exercise training increases the level of antioxidant enzymes but oxidative potential of the muscle increases more

• Nutritional antioxidants work with the enzymes

• Primary nutritional antioxidant vitamins are C, E, and beta-carotene

Recommended Intake of Antioxidant Vitamins

• Beta-Carotene– DRI: 10-11 mg– Recommended: 20 mg

• Vitamin C– DRI: 75-90 mg– Recommended: 250 mg

• Vitamin E– DRI: 22.5 IU– Recommended: 150 IU

Minerals

• Minerals are inorganic solid elements found in nature in plants, animal tissue, and water.

• 15 known essential minerals and 5 nonessential composing less than 4% of the body weight

Functions of Minerals

• Building blocks for body tissues such as bones, teeth, & muscles

• Components of metalloenzymes which regulate metabolism

• Exist as ions or electrolytes involved in metabolism & body water regulation

• Components of hormones

Classification of Minerals

• Macrominerals– RDA or ESADDI is > 100 mg per day or body

contains more than 5 grams– Calcium, phosphorus, magnesium, potassium,

sodium chloride, sulfur

• Trace Minerals– Needed in quantities < 100 mg– Iron, copper, chromium, selenium, boron,

vanadium, cobalt, fluoride, iodine, manganese, molybdenum

Calcium

• Major Functions– Bone formation– Enzyme activation– Nerve impulse transmission– Muscle contraction– Cell membrane potentials

Current DRIs for Calcium

• Ages 9-18– Males: 1300 mg– Females: 1300 mg

• Ages 19-50– Males: 1000 mg– Females: 1000 mg

Factors Altering Ca Absorption/Utilization

• Dairy sources absorbed better than plant– Vitamin D and lactose increase– Phytates in plants decrease

• Fiber decreases

• Excessive protein decreases

• Excessive coffee decreases

• Excessive alcohol decreases

Consequences of Low Ca

• Low serum calcium is rare because of the ability to absorb Ca from bones– Muscular cramping– Impaired muscular contraction

• Colon Cancer

• Osteoporosis

Consequences of Too Much Ca

• Abnormal heart rhythms

• Kidney stones

• Reduces iron and zinc absorption

Calcium Supplements

• Calcium citrate, carbonate, lactate, gluconate, antacids

• Citrate is the best for absorption

• Taken with meal is best

• Taken in 200-300 mg doses is best

Female Athlete Triad

• Disordered eating

• Secondary amenorrhea due to hormonal deficits and imbalances

• Osteoporosis

Iron

• Major Functions– Used to form hemoglobin, cytochromes, and

Kreb-cycle metalloenzymes• 70% is activety used• 30% is stored as ferritin

– As many as 90% of females get less than RDA but body partly compensates by increasing absorption

– 16% of females have iron-deficiency anemia

RDA for Iron

• Ages 9-13 yr– Males: 8 mg– Females: 8 mg

• Ages 14-18 yr– Males: 11 mg– Females: 15 mg

• Ages 19-50 yr– Males: 8 mg– Females: 18 mg

Types of Iron

• Heme iron– Animal sources– Best absorption: 10-30%– Animal sources are 40% heme, 60% non-

heme

• Non-heme iron– Plant sources– Poorly absorbed: 2-10%

Factors Affecting Iron Absorption

• Increases absorption– Vitamin C for non-heme iron– MPF for both heme and non-heme

• Decreases absorption– Tannins in tea (by 60%)– Phytic acid in whole grains– Oxalic acid in green leafy vegetables– Calcium for non-heme

Sources of Iron

• Animal– 4 oz liver- 10 mg– 4 oz beef, pork, dark poultry – 5-6 mg– 4 oz white poultry – 1 mg

• Plant– 8 oz prune juice – 3 mg– 1/3 cup dates, raisins, prunes – 1 mg– ½ cup spinach, beans, broccoli – 2 mg

Iron Deficiency

• Stage 1– Depletion of bone marrow stores and decrease in

serum ferritin• Stage 2

– Further decrease in serum ferritin and loss on some Hb, but Hb still normal

– 30-50% of female and 15-30% of male distance runners are in this stage

• Stage 3 (iron-deficiency anemia)– Very low serum ferritin and low Hb– < 13 grams Hb for males– < 11 grams Hb for females

Sports Anemia

• Low Hb levels due to expanded blood volume

• Iron stores are normal

Iron Supplementation and Performance

• Iron supplementation will improve performance in iron-deficiency anemia

• Iron supplementation will improve iron status in iron deficiency (stage 2) without anemia but may not improve performance

• Iron supplementation will not improve performance when iron stores are normal

Sodium or Natrium (Na+)

• Functions– Primary electolyte in extracellular fluid– Fluid balance and osmotic pressure– Nerve conduction and muscle contraction

Recommended Na+ Intake

• No RDA

• Minimal requirement is 500 mg

• Salt is 40% sodium

• Most recommendation is < 3000 mg/day

Effects of High N+ Intakes

• Associated with high BP in ~ 20% of population

• Water retention

Effects of Low Na+ Intakes

• Muscle cramps????

• Disruption of cardiac electrical activity which can result in death

Sources Containing 300 mg Ca

• 8 oz of milk

• 1.5 oz of cheese

• 1 cup yogurt

• 1.75 cups ice cream

• 8 oz fortified OJ

• 1 serving fortified cereal