Soy Foods

Is soy good or bad?

Soy contains many beneficial nutrients such as proteins, amino acids, phytoestrogens and Isoflavones (such as Genistein, Daidzein). Soy products have been consumed in Asian diets for over 5000 years.  This bean is readily available in supermarkets in the form of soy beans, soy milk, tofu, soy based protein powders, soy cheese, soy flour, soy yoghurt and tempeh.

There are many differing beliefs regarding the intake of Soy. One reason is the presence of phytoestrogens and there ability to mimic and influence hormonal balance within the body. Naturopathic ethos encourages moderation, and in relation to Soy products in most circumstances this is the best policy. A healthy diet should contain a well varied amount of grains, legumes, animal protein sources, nuts and seeds and fruits and vegetables.  Most Naturopaths will recommend that rather than drinking only one type of milk, to vary it and include other milk types such as dairy milk, oat milk, almond milk, rice milk, soy milk and goats milk.  Soy milk produced from genetically modified beans is also not recommended.  Variety and nutrition is the key to better health. The Western diet tends to contain many of the same foods, for example dairy, wheat and sugar and it is interesting to note that these are some of the most common foods implicated in food allergies.


As a general rule soy products, including soy based infant formulas are not recommended to give to young children and infants, especially if congenital hyperthyroidism is present.  This is because the high amounts of phytates present in soy and some other grains bind to many minerals (Calcium, Magnesium and Iron) in the immature digestive processes of infants and may cause malabsorption and deficiencies.  Soaking or fermenting these beans and grains reduces the phytate content.


Negative effects of soy are seen when there is an underlying thyroid condition as the phytoestrogens contained in soy or infant soy formulas inhibit the production and utilization of important thyroid hormones (thyroxine) causing complications (goiter, hyperthyroidism), thyroid imbalances and suppression of thyroid function.  Therefore people with thyroid conditions are cautioned to reduce their consumption of foods which contain high amounts of isoflavones i.e. genistein and equol, a metabolize of daidzen, as these may demonstrate toxicity in estrogen sensitive tissues and in the thyroid.


On the other hand soy has many health benefits as seen in studies which show that populations who consume a typical Asian diet commonly high in soy products, have lower incidences of reproductive, breast, prostate and colon cancers. Genistein has been shown to inhibit cancer cells and block the growth and proliferation of them, it is also a powerful anti-oxidant.


Isoflavones (a constituent of soy) are weak estrogens and resemble the natural estrogens in the body, they can therefore help to reduce excessive amounts of estrogen or sustain estrogen levels.  They are able to mimic hormones in the body and have a estrogen like effect and also help to lower estrogen dominance (estrogen dependant tumors) or reverse low estrogen levels in menopause.  These isoflavones have a beneficial effect on menopausal women and may ease menopausal symptoms such as hot flushes, vaginal dryness, reduced bone density, anxiety, thin and dry skin, low libido and fatigue.