Is there a Supreme Bean?

Go to Health: Is there a Supreme Bean?

Some insist that it’s coffee, but for many it’s the soybean, which nourishes hungry people throughout the world; its balance of essential amino acids makes soy a plant protein as valuable as eggs or meat.  Soy has been grown in China for some 5000 years, to enrich the soil (like other beans it has bacteria on its roots that fix nitrogen), and for human consumption.

Heart Disease Prevention:  Following studies showing significant decreases in serum cholesterol, LDL cholesterol (the ‘bad’ kind) and triglycerides, the FDA granted a health claim for soy in 1999: “25 grams of soy protein a day, as part of a diet low in saturated fat and cholesterol, may reduce the risk of heart disease.”  HDL, (‘good cholesterol’) did not increase.  Recently, new studies have challenged the ‘heart healthy’ claim for soy protein per se, but concede that soy milk, tofu, soy nuts and some soy burgers should be beneficial to heart health because of their polyunsaturated fats, fiber, vitamins and low content of saturated fat.  The American Heart Association said: “Using these soy foods to replace foods high in animal protein that contain saturated fat and cholesterol may confer benefits to cardiovascular health.” 

Breast Cancer:  Genistein and daidzein (so called phytoestrogens,  or plant estrogens) are substances in soy that are similar structurally to human estrogen but act differently in the human body.  They have much lower biologic activity than human estrogens and in some cases may function as anti-estrogens.  A recent study on breast cancer and soy from Vanderbilt University was encouraging.   The researchers looked at 5000 Chinese women in Shanghai, ages 20 -75, who were breast cancer survivors. They found those who ate the most soy (15 grams or more of soy protein daily) had a 29% lower risk of dying than those who consumed the least (5 grams or less).  A similar benefit appeared for breast cancer recurrence risk regardless of tamoxifen use.  The benefits of soy increased up to 11 grams of soy protein daily, and then leveled off or reversed, so more was not necessarily better.  The women ate mainly tofu and whole soy beans. The researchers warned that similar benefits can not be extrapolated to dietary supplements containing soy (pills, bars or foods containing isolated soy protein). The associations did not vary with menopausal status, cancer stage, or estrogen receptor status of a woman’s cancer.

Vitamin K2 & Hip Fracture: a recent study from the University of Tokyo School of Medicine showed that natto, a Japanese fermented soybean food, contains large amounts of Vitamin K2; there is increasing evidence that Vitamin K plays a positive role in bone strength and osteoporosis prevention.  Serum concentrations of vitamin K2 were significantly higher in frequent natto eaters, and the incidence of hip fracture was correspondingly lower, in every prefecture of Japan.

Soybean foods in the US: Today about 90% of soybeans grown in the US are genetically modified to make the plant resistant to the herbicide Roundup. Ninety percent of these beans are turned into soy oil and defatted soy meal that is fed to chickens, turkeys and pigs.  The abundance of soy meal, as well as corn, makes possible the new and very problematic industrial farming of these animals.  The US, Brazil and Argentina are major growers and exporters of soybeans, and the Brazilian crop has been responsible for a considerable loss of rainforest. Some soybeans, including organic soybeans, made into human foods in the US are imported from Brazil and China, where organic standards may differ from ours. Most Silk soymilk is no longer organic; the company was bought over by Dean Foods and switched many of their products to “natural” rather than organic. Edensoy products are made from organic soybeans grown in the US; Westsoy, Wildwood and others also have organic soy products.  If you care about this issue, read labels!   To get the benefits of soy, nutritionists advise people to eat whole soy products, such as tofu, tempeh, soy milk and soy nuts, rather than manufactured foods containing isolated soy protein.   Happy New Year, dear readers, and let us all appreciate the natural foods stores and organic farmers in West Marin.

Sadja Greenwood, MD, back issues at sadjascolumns.blogspot.com