Studies Short on Soy Formula Risks
Experts See Little Health Danger With Formula
By Todd Zwillich
WebMD Medical News
Reviewed By Louise Chang, MD
on Friday, March 17, 2006
March 17, 2006 -- There is not enough scientific data to determine whether
or not soy formula consumed by millions of infants poses a health risk, a
government panel concluded Friday.
Experts say they have little concern that an estrogen-like substance in soy
-- known as genistein -- poses a developmental risk to infants who consume
it or whose parents consumed it in soy-based foods.
Still, very few studies have looked at the long-term health effects of soy
formula, which is used to feed an estimated 25% of all U.S. infants, the
panel says.
Soy has raised concerns not only because of its exploding consumption by
U.S. infants and adults but also because studies have shown that genistein
can interfere with hormonal function in rats and their offspring.
A variety of toxic effects, including stunted growth, sexual organ
abnormalities, and decreased fertilization, have all been observed in
laboratory animals. All of the effects appear to be caused by genistein's
ability to mimic the effects of natural estrogen. Some researchers also
suspect soy of playing a role in reduced breast cancer rates in Japan, where
soy consumption is very high.
The committee says it had "negligible" concern that usual intakes of
genistein cause adverse health effects in newborns and infants who consume
soy formula, though one expert -- Ruth Etze, MD -- dissented from the
conclusion. Etzel, a pediatrician at the Alaska Native Medical Center in
Anchorage, could not be reached for comment.
Human infants consume much lower genistein doses than laboratory animals,
and most of the chemical is not absorbed into the human bloodstream, says
Karl Rozman, PhD, a University of Kansas toxicologist who led NIH panel.
But at the same time, few studies have looked at soy's effects in a
controlled way, he explains.
More Study Needed
"That means there are studies there, but they are not allowing us to come to
a firm conclusion one way or another. But it also means that we do not see a
problem," says Rozman.
One study pegged infant formula feeding as a risk factor for premature
breast development in girls. Experts called for better research to determine
if that and other potential health effects are real.
"Another case-control study to examine premature breast development in
females following exposure to soy infant formula is needed," the committee
concludes.
Panelist Jatinder Mhatia, MD, says soy formula has not shown "a blip on the
radar screen" in terms of ill health consequences, despite use by an
estimated 40 million total infants.
But Mhatia also says parents are up to 10 times more likely to give their
infants soy formula in the U.S. than in Britain. Some countries, including
Israel, have restricted formula use to prescription-only status for infants
who cannot consume milk. But American doctors are quick to recommend formula
for fussy infants, which parents are heavily encouraged by advertising to
use, he says.
"Only in our country are we using [soy] in a free-for-all," Mhatia, a
pediatrician at the Medical College of Georgia, tells WebMD. "Soy has a
specific indication, and we tend to use and abuse in America."
"Why should you use soy unless there's an indication?" he says.
--------------------------------------------------------------------------------
SOURCES: NTP-CERHR Expert Panel Report on the Reproductive and Developmental
Toxicity of Genistein, Center for the Evaluation of Risks to Human
Reproduction, National Institutes of Health, March 17, 2006. Karl Rozman,
MD, University of Kansas. Jitander Mhatia, MD, department of pediatrics,
Medical College of Georgia, Augusta.
© 2006 WebMD Inc. All rights reserved
Leanne Wynne
Midwife in charge of "Women's Business"
Mildura Aboriginal Health Service Mob 0418 371862
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