Douglas, Bob & Ward:  You should find this article from the October
1996 issue Pediatric News interesting.

IMMUNE SYSTEM COMPROMISED BY EXCESSIVE EXERCISE
AND LOW-FAT DIET

by Thomas M. Rosenthal, correspondent

BUFFALO, N.Y. -- While it is generally accepted that moderate exercise
and a low-fat diet are a healthy combination that can help the body
fight off infections, a recent study indicates that too much of a good
thing may actually produce the opposite result.

The first study to investigate the combined effect of diet and exercise
on immune function has shown that competitive long-distance marathon
runners who adhere to a very low-fat diet in hopes of improving
performance may actually be compromising their ability to fight
infection.  And, according to the study's lead researcher, the impact
on the immune system may even be more severe when the athletes are
teenagers.
The study, conducted by researchers from the State University of New
York at Buffalo, showed that white-blood cells (WBCs) collected after
maximum exercise from trained athletes on a moderate-fat (30%) diet
multiplied faster than WBCs from the same athletes after spending four
weeks on a low-fat (15%) diet.
The study also found that switching from a low-to moderate- fat diet
dramatically increased the number of natural killer cells, said Jaya T.
Venkatraman, PhD, SUNY Buffalo assistant professor of nutrition and
lead researcher of the study.
Blood analysis of the seven men and seven women athletes showed that
secretion of interleukin 2 (IL2) protein, which is known to enhance
immune function, increased when runners went from a low- to moderate-
fat diet.  IL2 levels decreased slightly when runners increased dietary
fat from moderate to high, but still remained higher than when they
were on a low-fat diet.
"Moderate exercise enhances immune status, but when athletes exercise
to the maximum, it stresses the immune system, especially when they are
training heavily and don't get enough rest," said Venkatraman.  "This
leaves them susceptible to upper respiratory infections."
While the study dealt with 14 adult athletes, all in their mid-30's,
Venkatraman speculated that the combination of a very low-fat diet and
an excessive physical training regimen would more severely affect the
immune systems of teenage athletes because they are still developing.
"One of the reasons for the study is to recommend a better protocol for
training, rest, and diet," said Venkatraman.  The findings will be
published in *Medicine and Science of Sports and Exercise*, the
official journal of the American School of Sports Medicine.  The study
was presented earlier this year at the annual meeting of the Federation
of American Societies for Experimental Biology in Washington, D.C.
Also working on the study were David R. Pendergast, PhD, professor of
physiology, Peter Horbath, PhD, professor of nutrition, and John Leddy,
PhD, professor of sports medicine at Buffalo.
"Athletes are continually seeking the right diet and ideal protocol for
increasing performance," Venkatraman said.  "Immune function is an
important factor.  We have shown that a low-fat diet, adhered to by
many competitive athletes, may not be best for the immune system, while
increasing dietary fat to moderate levels improves it.  Even when we
raised dietary fat to 45%, there was no negative effect on the immune
response."
All of the participants ran an average of 40 miles a week.  They spent
four weeks on three successive diets composed of 15% fat, 30% fat, and
45% fat.  To study the influence of the dietary-fat level and exercise
on the immune response, Venkatraman collected blood samples from the 14
runners before and after they completed each diet regimen, at rest and
after they performed a maximal exercise test.  She found that exercise
significantly increased the number of leukocytes, but when challenged
*in vitro*, the ability of the white cells to multiply and meet the
"assault" was impaired on the low-fatdiet.
"The bottom line is, in highly trained athletes, a moderate-fat diet is
better for the immune system and a high-fat diet doesn't hurt it," said
Venkatraman.  "It is one more piece of evidence that a diet very low in
fat may not be beneficial for performance athletes.   A lot more work
needs to be done on the influence of diet and exercise on the immune
function before we have a definitive answer, but so far results on a
moderate- to high- fat diet have been positive."

For more information:

Venkatraman JT, Rowland JA, DeNardin E, et. al.  Influence of level of
dietary lipids and exercise on immune status in athletes.  Federation
of American Societies for Experimental Biology Journal.  1996;3203:556.

Best, Peter
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