I ate dinner last night with another plant-based interventional cardiologist (triathlete Heather Shenkman, MD) at Vinh Loi Tofu in California and had one delicacy after another featuring homemade tofu crafted by the culinary genius Kevin Tran. How can two cardiologists enjoy soy as a healthy food choice when so many websites and media comments emphasize the dangers of eating soy? Have I lost my mind?
With the new USDA dietary guidelines emphasizing "a diet higher in plant-based foods such as vegetables, fruits, whole grains, legumes, nuts and seeds lower in calories and animal-based foods is more health promoting and is associated with less environmental impact than is the current US diet," more people may be exploring tofu in their diet.
Dr. Neal Barnard of the Physicians Committee for Responsible Medicine reviewed data on soy and health in 2012, so I took a look at recent medical research on soy to ensure that my meal last night was a health-promoting choice.
1. Soy and heart attacks
Chinese researchers studied 1,312 cases of first-time heart attack sufferers and 2,235 control subjects. An unhealthy dietary pattern increased the risk of heart attack while increased intake of vegetables, fruits and tofu were associated with a significant drop in heart attack rates. So I guess two cardiologists made a good choice.
2. Soy and prostate cancer
A meta-analysis of men diagnosed with prostate cancer found that the risk of this serious disease was cut in half by regular ingestions of soy and soy isoflavones.
3. Soy and breast cancer
Japanese researchers performed an evaluation of research and identified studies that showed everything from a slight to a significant reduction in breast cancer with increased soy food intake.
Additionally, a meta-analysis of 35 studies from Asian countries was performed to examine soy intake and breast cancer risk. Soy intake significantly reduced breast cancer risk by 40% in both pre- and post-menopausal women in these countries.
4. Soy and eczema risk
The association between maternal intake of a soy product called natto during pregnancy and the risk of eczema in the babies born of these pregnancies was assessed by researchers. They found much lower incidence of eczema in babies of mothers who ate the most natto.
5. Soy and ovarian cancer
In southern China, 500 women with ovarian cancer were compared to 500 controls, and the amount of soy products eaten was assessed. Regular soy intake was associated with a dramatically lower rate of ovarian cancer with a dose-response relationship.
6. Soy and mortality
The Singapore Chinese Health Study examined more than 52,000 men and women free of chronic diseases at entry between 1993 and 1998, and followed them through 2011. During that time, there were more than 10,000 deaths. A pattern of eating a vegetable-, fruit- and soy-rich diet was associated with up to a 25% less risk of dying during the study period, and included fewer heart and cancer deaths.
The bulk of the data that has emerged from scientific studies, admittedly often of Asian populations and based on associations, supports the promotion of soy products in the diet for health optimization. Clearly there are individuals with soy allergies who should avoid this class of foods.
Ideally, you'd only choose non-GMO and organic products, which can be difficult since the majority of soy-based products are GMO. Genetically modified soybeans are routinely fed to animals for meat production and may be a source of concern for those regularly ingesting nonorganic sources of meat.
Dan Buettner, author of The Blue Zones, has said that "black beans and soy beans are the cornerstones of longevity diets around the world." If you have a chance, say hi to Kevin at Vinh Liu Tofu, and sample some of his healthy (and possibly life-extending) delicacies.