Nancy Brinch, MS, RD, LSW,
is Richard Stockton College's campus nutritionist. She obtained
her BS in Food and Nutriton from the Univ. of Delaware and her Master's
in Nutrition from Penn State Univ.
She provides individual, confidential nutritional counseling to
students. Her service is free for RSC students. For appointments
call extension 5740. Nancy Brinch can be contacted at Nancy.Brinch@stockton.edu |
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Dietary Supplements: Factually
Speaking
By Nancy Brinch, MS, RD, LSW
 Athletes
often take dietary supplements in the hope that supplements will
give them a competitive edge which will improve their performance.
These dietary supplements include vitamins and minerals as well
as ergogenic aids. This article will address some of the ergogenic
aids used by athletes.
The term ergogenic means "work-producing." Since competitions can
be won by a fraction of a second, athletes may take these supplements
in an attempt to increase speed, enhance muscle mass, improve endurance,
speed recovery time, and reduce body fat. Most of these supplements
have very little scientific evidence supporting their claims. Much
of the research on these products is of poor quality and has not
been published in reputable, peer-reviewed journals.
The word "natural" on a supplement label often leads an athlete
to think this means the product is "safe" and "legal." This can
be a dangerous assumption. Supplement manufacturers do not have
to prove their products are safe,  effective
or potent before they put the products on the market. Unlike medications,
dietary supplements do not have to be approved by the Food and Drug
Administration for safety or effectiveness. Manufacturers are not
supposed to make unsubstantiated claims about their products, but
they get around this requirement by placing the following disclaimer
on the label: "This statement has not been evaluated by the Food
and Drug Administration. This product is not intended to diagnose,
treat, cure or prevent disease." Often this disclaimer is placed
on the back of the label in small print. An additional risk for
collegiate athletes is these products may contain banned substances
that could cause the failure of a drug test. Buyer beware!!!!
Amino acids
Branched chain amino acids (BCAA): Claims for BCAA tout they
can prevent fatigue and increase aerobic endurance. Scientific data
does not show any performance enhancing benefit from taking BCAA.
Consuming large amounts of BCAA during exercise can slow water absorption
from the gut and cause gastrointestinal pain. Adequate quantities
of BCAA can be obtained from food. Supplements may not be safe or
effective. SUPPLEMENTS NOT RECOMMENDED
Arginine, lysine, ornithine: Claims for these amino acids
include increased muscle mass, decreased body fat, and increased
human growth hormone (hGH) secretion. Scientific research has shown
that supplementation with these amino acids does not have any impact
on body composition or on hGH levels. Consuming large amounts of
any single amino acid can interfere with the absorption of other
amino acids, cause gastric distress, and result in metabolic imbalances.
Sufficient amounts of amino acids can be found in food (see previous
article Protein: Power or Propaganda).
SUPPLEMENTS NOT RECOMMENDED
Beta-Hydroxy-Beta-Methylbutyrate (HMB)
Claims for this ergogenic aid include increased muscle mass, decreased
body fat, and increased strength and power. The limited research
on HMB was performed by the laboratory that developed it. This research
showed no statistically significant increase in muscle mass in subjects
who took HMB compared with control subjects although strength did
increase in subjects who took HMB. No other research has reproduced
these results. HMB is expensive, and its potential benefits are
questionable. SUPPLEMENT NOT RECOMMENDED
Chromium picolinate (CrPl)
Promoters claim CrPl can increase muscle mass, decrease body fat,
and it is a safe alternative to anabolic steroids. These claims
are based on research reported in 1989 that has been widely criticized
for its poor quality. Subsequent research has shown no change in
strength or body composition after taking  CrPl.
Subjects taking CrPl excreted more chromium in their urine. The
amount of chromium used in these studies (200 micrograms) is considered
safe (National Research Council considers 50-200 mcg. of chromium
to be safe and adequate.) This amount of chromium can be obtained
from foods such as nuts, whole grains, cheese, asparagus and brewer's
yeast. In 1996 the Federal Trade Commission ordered the three largest
distributors of CrPl to stop making unsubstantiated claims about
CrPl (such as increased muscle mass, decreased body fat, and increased
energy.) SUPPLEMENT NOT NECESSARY
L-Carnitine
Claims for L-carnitine include increased use of fatty acids for
fuel, decreased body fat, and increased endurance. Research on this
supplement shows no beneficial impact on exercise performance. The
supplement appears to be safe, although concerns have risen over
the possible contamination with D-carnitine that can deplete L-carnitine
in the body. Carnitine is found in meats, and it is synthesized
in the body. SUPPLEMENT NOT RECOMMENDED
Conjugated LinoleicAcid (CLA)
Most of the research on CLA has been conducted on animals. Mice
fed CLA have significantly less body fat and increased muscle tissue
compared with controls. Until well-controlled studies have been
undertaken in humans CLA supplements are not warranted. No adverse
reactions to CLA supplementation have been reported. SUPPLEMENT
NOT RECOMMENDED AT THIS TIME
Pyruvate
Promoters of pyruvate claim it increases aerobic endurance, increases
metabolic rate and decreases fat mass. Only two research studies
have shown any evidence of improved endurance after taking pyruvate.
In both studies untrained male subjects were given high doses of
pyruvate plus dihydroxyacetone. These studies should not be used
to justify supplementation because 1) the subjects were given amounts
of pyruvate much higher than the amounts found in commercial preparations,
2) many commercial supplements do not contain dihydroxyacetone which
was used in the research and 3) the subjects experienced side effects
such as intestinal gas, flatus, and diarrhea. SUPPLEMENT NOT
RECOMMENDED
Source: Rosenbloom CA, ed. Sports Nutrition: A Guide for the
Professional Working with Active People. Chicago, IL: American Dietetic
Association Sports, Cardiovascular, and Wellness Nutritionists Dietetic
Practice Group; 2002. |
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