In the twentieth century the soybean was one of the two major new crops introduced into the U.S. (the other crop being canola). It has now become the number one export crop and one of the second largest crops for cash sales.
Most soybean products are processed into oil (shortening, margarine, cooking oil & salad dressings) and meal. For example, you may have noticed (or may start noticing) the popular ingredient “Soy Lecithin” in many of your foods and household items. There was a time when soy was praised a superfood, from combating cancer and high cholesterol. However, new evidence has emerged with soy’s negative impact on health (and the environment). Read on to discover the deceptions and dangers of soy.
Health Dangers of Soy
1. Impaired immune system – Soy contains endocrine disrupting chemicals called phytoestrogens (specifically Genistein and daidzein) (1, 2, 3). They influence the reproductive organs as well as the immune system. In one study they found that mice treated with genistein (soy isoflavone) had less interferon (IFN)-gamma in culture supernatants (4) compared to mice treated with oil. Interferon-gamma is a cytokine that is crucial in innate and adaptive immunity against viral and bacterial infections and tumour control. Decreased levels of this molecule mean decreased immunity and decreased tumour control.
2. Impaired Fertility – Soy isoflavones as seen in point 1 (above), are structurally similar to endogenous estrogens and display both estrogenic and weak anti-estrogenic activities (5). Impaired fertility and reproductive tract disorders can be a result of said activities. In female rats exposed to high doses of isoflavones their fertility decreased (6, 7) and had altered estrous cycling (8) – it also led to increased uterine weight and epithelial cell height which may contribute to ovarian cysts. Studies done with male rats had no found effects on sexual maturity, preputial separation, fertility, sperm count or testosterone levels (8).