Some health controversies about soy center on
compounds called isoflavones that are found in abun-
dance in soybeans. These compounds have a chemical
structure similar to the female hormone estrogen. Sev-
eral health effects, both positive and negative, have
been attributed to isoflavones. In 2006, the American
Heart Association concluded that isoflavones are not
the cause of the cholesterol-lowering, heart-healthy
properties in soy and that dietary supplements con-
taining soy-derived isoflavones do not have the same
cardiovascular benefits as whole soy.
Another claim is that isoflavones can improve bone
health in women. This claim appears plausible because
of the chemical similarity between isoflavones and estro-
gen. Estrogen is known to increase the amount of
calciumdeposited in bones, and the lack of estrogen in
post-menopausal women is linked to decreasing estrogen
levels. However plausible the connection between bone
health and isoflavones in soy may be, studies have pro-
duced inconclusive results. As of 2007, any effect that soy
may have on bone health appears to be weak. Also,
because of their estrogen-like structure, isoflavones
from soy have been touted as a dietary supplement that
will help prevent symptoms of menopause such as hot
flashes. A committee of the AHA that investigated iso-
flavones found that they had no effect on hot flashes.
A far bigger health question concerns the relation-
ship between isoflavones andcancer. The AHA com-
mittee found that despite claims that soy isoflavone
supplements can treat and prevent breast, endometrial,
and uterine cancer in women andprostatecancer in
men, there was no evidence to suggest that this treat-
ment was safe or effective. On the other hand, there was
also no evidence that, as some experts have suggested,
soy increases the chance of post-menopausal women
developing breast cancer. A large number of federally
sponsored clinical trials are underway to investigate
these and other effects of isoflavones and soy.
PrecautionsAlthough soy is often thought of as a benign food,
some people are allergic to soy.
InteractionsSoy contains compounds called goitrogens. Goitro-
gens interfere with the body’s ability to absorb or use
iodine. The goitrogens in soy should not cause problems
with iodine uptake in healthy people, but people with
thyroid deficiencies should discuss with their healthcare
provider whether they should limit soy in their diet.
Complications
No complications are expected from eating soy
products.Parental concerns
One long-term study is underway to investigate
the effect of increased concentrations of isoflavones in
the blood of children who drink soy formula. The
study plans to look for potential effects across a period
of about 20 years, so no results are available yet.Resources
BOOKS
GeniSoy Products.The Magic of Soy: Healthy Cooking with
Soy ProteinSummertown, TN: Book Pub. Co.,2000.
Hagler, Louise.Soyfoods Cookery: Your Road to Better
Health.Summertown, TN: Book Pub. Co., 1996.
Riaz, Mian N.Soy Applications in FoodBoca Raton, FL:
CRC, 2006.
Sears, Barry.The Soy Zone.New York: ReganBooks 2000.
Shurtleff, William and Akiko Aoyagi.Tofu & Soymilk Pro-
duction: A Craft and Technical ManualLafayette, CA:
Soyfoods Center, 2000.
PERIODICALS
American Heart Association Science Advisory Board. ‘‘Soy
Protein, Isoflavones, and Cardiovascular Health.’’
Circulation113(2006):1034-44.<http://circ.ahajournals.
org/cgi/content/abstract/113/7/1034>
Henkel, John. ‘‘Soy: Health Claims for soy Protein, Ques-
tions About Other Components.’’FDA Consumer
(May–June 2000).<http://www.fda.gov/Fdac/features/
2000/300_soy.html>
Sears, Barry. ‘‘The Soy Zone—Diet That Helps Balance the
Body.’’Vegetarian Times(September 2000).<http://
findarticles.com/p/articles/mi_m0820/is_2000_Sept/
ai_65802972>
Szalavitz, Maia. ‘‘How Healthy is Soy?’’Psychology Today
(May–June 2006).<http://psychologytoday.com/
articles/pto-20060426-000001.html>
ORGANIZATIONS
American Soybean Association. 12125 Woodcrest Executive
Drive, Suite 100, St. Louis, MO 63141. Telephone: (800)
688-7692. Website:<http://www.amsoy.org>
Soyfoods Association of North America. 1723 U Street NW,
Washington, DC 20009. Telephone: (202) 986-5600.
<http://www.soyfoods.org>
United Soybean Board. 424 Second Avenue West, Seattle,
WA 98119. Telephone: (800) TALK-SOY (825-5769).
Website:<http://www.talksoy.com>and<http://
http://www.soyfoods.com>
OTHER
Soyfoods Association of North America. ‘‘Soy Safety.’’
2007.<http://www.soyfoods.org/healthy/soy-safety>
United States Department of Health and Human Services
and the United States Department of Agriculture.Soy