Soy: Health Food or Toxin?
It seems the Europeans are far ahead of Americans when it comes to soy. In July of 1996, the British Department of Health issued a warning that the phyto-estrogens found in soy-based infant formulas could adversely affect infant health. Soy formula should only be given to babies on the advice of a health professional after careful consideration. Why? Soy has been an essential protein source in vegetarian diets for years. In many cultures, soy is a basis of most dishes. However, it is not without its disadvantages, and in order to decide if it is a healthy food for you, you need to be aware of all of soy’s attributes. For instance, extracting soy into soy milk is a modern western invention as an alternative to dairy. Traditionally, soy was never processed in this way. It was always steamed, curdled or fermented. Also many soy proteins have been isolated and added to protein shake mixes, frozen food and as binders and fillers, all of which are also non-traditional.
Since the late 1950’s researchers have identified soy as a phytoestrogen. This prompted women to add larger amounts of soy into their diet as they reached menopause in order to offset the lessening of their inherent estrogen production. The estrogenic effect of soy is 1/500th the potency of estrogen that is naturally circulating in our body. But it is important to realize that soy acts as a competitive inhibitor of estrogen at the cellular receptor sites, reducing the effect of inherent estrogen in our body. Now this can be a great thing for those who are estrogen dominant. At the same time, excessive soy consumption can overwhelm many of the bodies’ cells with such weak estrogen-like hormones, that an overabundance of estrogen may occur. So moderation seems to be key here.
But soy isn’t all peaches and cream. Soy contains toxic cyanogenic glycosides (an issue that is negated substantially when soy is cooked or fermented). CG’s inhibit optimal iodine absorption and are not healthy for thyroid function, so those with underactive thyroid should really stay away from soy. But that also means that the reverse is true. If you have an overactive thyroid, larger amounts of soy may be a natural alternative to drug therapy. Soy also contains phytates that inhibit the GI absorption of minerals, unless the soybeans are soaked overnight and then cooked or fermented. Phytate levels are very high in soy milk which is generally not cooked nor fermented, and soy milk can be drunk in such large amounts that many mineral deficiencies in vegetarians are linked to their soy milk consumption.
Another problem is that here in the United States, and increasingly elsewhere, soy beans are genetically modified. More and more farmers are realizing the benefits of soybean cultivation, but are turning to GMO sources for their start. Soy milk also contains large amounts of aluminium as a stabilizing agent, which has been linked to Alzheimer’s Disease and loss of mental acuity. Then there are the isoflavones that are found in soy products, including genistein. These are inhibitors of thyroid peroxidase that is essential in thyroid hormone production. Isoflavones seem to actually be toxic in the concentrations found in soy milk.
A large part of the problem that I have seen in my own patients is the large amount of soy introduced into the diets of vegetarian children, even from infancy. As I’ve pointed out, u nfermented soy products such as tofu and particularly infant soy formula contain allergens, enzyme inhibitors, hormone modifiers and mineral blockers that interfere with essential functions, such as the thyroid. Thyroid dysfunction in children can have a devastating effect on growth, bone development, metabolism and weight. Many vegetarian girls are reaching puberty before the age of 12, which may have a great deal to do with large amounts of phytoestrogenic soy consumption.
Infants fed long term soy formula during childhood are particularly vulnerable to the development of autoimmune thyroid disease. In fact, studies have found a correlation between the frequency of feedings with soy-based milk formulas in early life and the development of autoimmune thyroid disease later in life. The incidence of thyroid disease was almost triple in those soy formula-fed children compared to their siblings and healthy unrelated children.
It seems the Europeans are far ahead of Americans when it comes to soy. In July of 1996, the British Department of Health issued a warning that the phyto-estrogens found in soy-based infant formulas could adversely affect infant health. Soy formula should only be given to babies on the advice of a health professional after careful consideration.
Soy-based infant formula, initially developed for infants who were lactose-intolerant or allergic to cow’s milk-based formula, now account for >25% of the infant formula sold in the United States. A systematic review of the literature suggests that modern soy-based formulas can support normal growth and nutritional status in healthy term infants in the first year of life. However, there is very limited data on sexual and reproductive development or outcomes such as immune function, visual acuity/cognitive development and thyroid function. Available data does not provide evidence of meaningful differences in timing of maturation, sexual development or fertility in adolescents or adults.
So how much is too much? This varies depending on age. According to the Soy Online Service, infants should not take in any soy. For adults, just 30 mg. of soy isoflavones per day is sufficient to have a negative impact on thyroid function. This amount of soy isoflavones is found in just 5-8 ounces of soy milk, or 1.5 ounces of miso. Interestingly, while miso has a phytoestrogenic effect, it does not have the enzyme-inhibitory effect because it is fermented. Other fermented soy products include soy sauce or tempeh.
The current promotion of soy as a health food will likely result in an increase in thyroid disorders and possibly raise the risk of thyroid cancer in decades to come. Remember that it takes an average of 20 years before chronic physiological insults to the body surface as a disease state. Don’t be one of the statistics.