Soy products are adequate substitutes for meat and dairy products.
The billion-dollar soy industry has profited immensely from the anti-cholesterol, anti-meat gospel of current nutritional thought. Whereas, not so long ago, soy was an Asian phenomenon, now soy products proliferate in the North American market. While the traditionally fermented soy products of miso, shoyu, tempeh and natto are definitely healthful in measured amounts, the hyper-processed soy "foods" are not.
Non-fermented soybeans are extremely high in phytic acid (54), an anti-nutrient that binds to minerals in the digestive tract and carries them out of the body. Vegetarians are known for their high rates of iron and zinc deficiencies (55).
Soybeans are also rich in trypsin inhibitors, which hinder protein digestion. Textured vegetable protein (TVP), soy "milk" and soy protein powders, and popular vegetarian meat and milk substitutes are entirely fragmented foods made by treating soybeans with high heat and various alkaline washes to extract the beans' fat content or to neutralise their potent enzyme inhibitors. These practices completely denature the beans' protein content, rendering it very hard to digest. MSG, a neurotoxin, is routinely added to TVP to make it taste like the various foods it imitates (56).
On a purely nutritional level, soybeans, like all legumes, are deficient in cysteine and methionine, vital sulphur-containing amino acids (56). Soybeans are also lacking in tryptophan, another essential amino acid (56).
Furthermore, soybeans contain no vitamins A or D, required by the body to assimilate and utilise the beans' proteins (56). It is probably for this reason that Asian cultures that do consume soybeans usually combine them with fish or fish broths, The New Zealand government is considering removing soy formula from the market and making it available only by prescription (58).
Though research is still ongoing, some recent studies have indicated that soy's phyto-oestrogens could be causative factors in breast cancer and infantile leukaemia (59). Regardless, soy's phyto-oestrogens, or isoflavones, have been shown to depress thyroid function and cause infertility in some animals (60). As a practitioner, I have seen more than my share of vegetarians with hypothyroidism. They invariably rely on soy foods to get their protein.