Chester J. Zelasko, Ph.D. |
April 2, 2002
You see them all the
time--headlines screaming that "Substance X Causes This Disease" or
"Substance Y May Cure That Disease." Sensational headlines may confuse
consumers because they just don't know what to believe.
The science of what causes and what cures diseases is a lengthy and
laborious process. What frequently happens is that we get pieces of a puzzle
that will take years to complete. The challenge is to discern from this
information what changes we can incorporate into our lifestyles now--changes
that, while still unproven beyond all doubt, may help us and at the very
least won't harm us.
One such piece of the health puzzle was a recently published study on soy
isoflavones and breast cancer (1). Soy isoflavones are substances in
soybeans that act like phytoestrogens, literally meaning "plant estrogens."
They have a mild affinity for estrogen receptors in the body. Higher levels
of estrogen have been implicated as a possible cause of breast cancer.
Phytoestrogens have been the subject of much research because if the intake
of soy products can reduce estrogen levels, it may reduce the risk of
developing breast cancer.
That was the premise of this study. Subjects were given either a placebo or
40 mg of the soy isoflavone genistein every day for 12 weeks. The amount of
the supplement reflects the amount of isoflavone typically eaten by an Asian
population known for having lower rates of breast cancer. The results of the
study indicated that levels of female hormones such as estrogen were lower
in the women who took the supplement. They also had longer menstrual cycles.
The implication is that if the cycles were longer, they would have fewer
cycles over a lifetime. Thus, the reduction in exposure of breast tissue to
estrogen over a lifetime would likely reduce the rate of breast cancer.
There seemed to be few side effects of taking the isoflavone other than
gastrointestinal problems such as gas and bloating.
This study was not perfect. About one-third of the subjects dropped out,
mostly because they couldn't remember to take the supplements. It was short,
lasting only 3 months. However, the side effects were few and only occurred
in a few women, and the potential for benefit is good. Therefore, when
combined with all the other studies on isoflavones, it's reasonable to
suggest that women consider eating more soy products such as tofu,
texturized soy protein, and/or take a supplement that contains isoflavones
to promote breast health.
Health is not found in popping pills but in a consistent, persistent effort
to learn healthier habits that include: eating lots of fruits and
vegetables; lowering fat intake, especially saturated fats; maintaining a
normal body weight; and getting some exercise every day. Adding more
isoflavone-containing soy products is a reasonable addition to those health
- Kumar N, et al. The Specific Role of Isoflavones on Estrogen
Metabolism in Premenopausal Women. Cancer 2002. 94:1166-1174.