Essentials of Nutrition for Sports

For almost all vitamins and minerals, doses beyond the RDA
cause side effects that not only

can decrease performance, but also

can cause disability or death. •^

Vitamin A

excess can cause headache, loss of appetite, vomiting,

hair loss, itching, bone pain,

and kidney and liver damage. Long-

term use is associated with osteoporosis and hip fractures.

-^

Vitamin B

3 (niacin)

prevents the release of fatty acids. This can

adversely affect endurance performance. Excess B

3 can release

histamine, causing flushing, itching, asthma, and gastrointestinal problems. Vitamin B

3 can cause gout, diabetes, and liver

damage.

-^

Vitamin B

6 (pyridoxine)

can cause depletion of glycogen stores.

An excess can cause neurologic problems, including clumsiness and gait disturbance. It can interfere with the action of prescribed medicines.

-^

Folic acid

excess can camouflage vitamin B

12 deficiency,

allowing neurologic problems associated with B

12 deficiency to

progress unchecked.

-^

Vitamin C

excess can cause decreased levels of vitamin B

12

,

increase estrogen levels, and cause diarrhea and kidney stones.

-^

Vitamin D

excess can cause increased calcium in the blood and

kidney stones.

-^

Vitamin E

excess can cause malaise, gastrointestinal problems,

blurred vision, headache, bleeding tendencies, and possibly hypertension.

-^

Vitamin K

excess can interfere with the action of prescribed

medicines and cause jaundice in a newborn infant.

-^

Calcium

excess can cause kidney and neurologic disease.

-^

Chromium

excess can cause kidney failure and lung cancer.

-^

Copper

excess can cause liver and kidney disease, anemia, and

mental deterioration.

-^

Fluoride

excess can cause mottled t

eeth, gastrointestinal

problems, muscle contractions, and heart disease.

-^

Iron

excess can cause liver failure; diabetes; testicular atrophy;

arthritis; and heart, skin and neurologic disease.

-^

Magnesium

excess can cause tremor, spasm, rapid heart rate, and

high blood pressure.

-^

Manganese

excess can cause headaches, weakness, cramps,

impotence, Parkinson-like symptoms, and psychosis.

-^

Molybdenum

excess can cause gout.

-^

Selenium

excess can cause hair loss, fingernail abnormalities,

emotional problems, and fatigue.

-^

Sodium

excess can cause fluid retention and high blood pressure.

Weight gain can limit performan

ce in weight-dependant sports.

-^

Zinc

excess can cause stomach ulcers, pancreatitis, lethargy,

anemia, fever, nausea, and lung problems. Zinc excess reduces “good” cholesterol (HDL) and increases “bad” cholesterol (LDL). It is also associated with impaired immune function and decreased copper absorption.

Conclusion

The functions, increased requirements, and ergogenic and

ergolytic effects of vitamins and minerals are summarized in

Table

26

, below. In athletes without nutritional deficiencies, nutritional

supplements do not exhibit an ergogenic effect.

Ideally, get the recommended daily allowance from food. If your

diet is not ideal and you wish to supplement, do so only up to the RDA.

Megadoses not only may fail to improve performance but also

may be toxic.

Nutrition for Sports, Essentials of 128