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
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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% nonheme
• 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
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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
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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