The Physicians Committee

No Debate: Soy is Beneficial to Health

  March 2, 2016    

There’s no debate: Soy is beneficial to your health. Soy products have been shown beneficial for lung cancer prevention and survival, prostate cancer prevention, heart health and diabetes, bone health, inflammation, and hot flashes, among other conditions.  

Soy is also beneficial in reducing breast cancer risk and in breast cancer survival. Xiao Ou Shu, M.D., M.P.H., Ph.D., who established the Shanghai Breast Cancer Survival Study, a cohort of more than 5,000 breast cancer survivors and who has also led several other epidemiological studies on soy food and breast cancer risk, will discuss the influence of soy food consumption on breast cancer risk and survival at this summer’s International Conference on Nutrition in Medicine.

Below, Dr. Shu answers a few questions about soy products and breast cancer survival that she will cover in depth at the conference.


Please describe your study.

We have applied both cohort and case-control study designs in our research. For the former, we followed up one group of women who were initially free of breast cancer for a risk association investigation or who were newly diagnosed with breast cancer for survival research. The risk of breast cancer or recurrence/death was compared for women who had high soy food consumption versus those with a low intake.

Study participants for case-control study are a group of breast cancer patients and healthy control. We measured the risk association by comparing the soy food consumption of breast cancer patients to that of healthy women.

Why are scientists looking at soy products in relation to breast cancer survival?

Estrogen plays a central role in breast cancer development and progression. Soy foods not only have an antiestrogen effect but also have antiproliferation, antioxidation, and many other anticancer properties. Both laboratory and epidemiological studies have shown that soy food and soy components can reduce breast cancer recurrence and increase survival rates. Evidence is quite consistent that soy food consumption at the level of the traditional Asian diet is associated with a reduced breast cancer risk. Epidemiological research on soy food consumption has not shown any soy product to be more beneficial than others.

How does general nutrition and lifestyle impact breast cancer?

Vegetables and a diet enriched with antioxidants are also beneficial to breast cancer survivors. Red meat and a high fat diet, on the other hand, should be avoided. Low physical activity, obesity, diabetes, and likely chronic inflammation also play an important role in breast cancer development and prognosis.


Soy intact as infants vs adults

So many studies looking at soy intake look at cultures where soy has been eaten since infancy. I would expect there to be a significant different on the impact of soy when eaten from infancy since it could have a direct impact on breast tissue as it develops. I doubt it would have the same impact when initiated as an adult. I don't understand why studies don't take into account the age of when soy intake was initiated.

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