Essentials of Nutrition for Sports

In athletes without vitamin and mineral deficiencies, nutritional
supplements do not exhibit an ergogenic effect.

For a specific discussion of an individual vitamins or minerals,

see the chapter on that specific vitamin or mineral.

Increased Performance The Claims—Purported Benefits

All the vitamins, with the exception of vitamin K and biotin,

have been claimed to improve performance.

“Vitamin B15”—pangamic acid—is an example of a substance

sold to athletes with no recognized status in the scientific community and little to recommend it beyond hope and a placebo effect.

For theoretical reasons, sport scientists have considered that six

trace minerals may possibly have a

role in athletic performance:

chromium, copper, iron, phosphorus, selenium, and zinc. Only iron, phosphorus, and zinc have been shown in studies to have any ergogenic potential. Read more about iron and phosphorus in the free

supplement to this book available at: http://roadbikerider.com/nutritionforsportssupplement.htm

.

Possible Benefit of Vitamin-Mineral Supplements •^

Pantothenic acid

reduced oxygen use for

a given workload in a

group of runners in one study. Others studies show no benefit.

-^

Antioxidant vitamins

are vitamins C, E, and beta-carotene (a

precursor form of vitamin A). Overall, they have not been shown to improve performance. For more information about antioxidants, see page

25

.

-^

Vitamin C

has been shown to improve performance in a few

studies but has also been shown not to improve performance in the majority of studies. The best-designed studies tend to show no effect.

-^

Vitamin E

has been shown to improve performance in a couple

of studies. Many more show no benefit.

-^

Iron

has been shown to improve performance in athletes who are

iron-deficient and anemic. In the absence of anemia, it has not improved performance.

-^

Phosphorus

in the form of phosphates has been shown in some

studies to improve performance. Other studies show no benefit.

-^

Zinc

has been shown to improve some measures of muscle

performance in one study. Other studies show no benefit.

-^

Studies have specifically failed to demonstrate performance benefit for Vitamins A, D, B

1 , B

2 , B

3 , B

6 , B

12 , biotin, folic acid,

copper, and selenium.

Decreased Performance

Many athletes take out “extra insurance” and consume large

doses of almost all known vitamins and minerals— “just in case.”

One problem associated with supplements is that an excess of

one vitamin or mineral may interact with and affect the absorption or metabolism of another vitamin or mineral. Because of such an interaction, a deficiency may result even though the other vitamin or mineral is present is “normal” am

ounts. Balance is sometimes more

important than quantity.

The vast majority of studies have not found any improvements in

exercise performance with individual or combination vitamins or minerals.

Many studies have shown that supplements can

decrease

performance.

This is particularly true for v

itamin B3 (niacin) and vitamin B6

(pyridoxine) whose ergolytic effects are via direct energy-related mechanisms.

Nutrition for Sports, Essentials of 127