Soy: Friend or Foe

Q. Soy: Friend or foe? I am writing this in response to a recent question I saw in a newspaper about possible health concerns for men who consume soy products. I thought it was a great question and I would like to clarify a few common misconceptions about soy and its estrogenic effects, as well as comment on some other substances in our day to day environment that are both more difficult to avoid, and could be causing much more damage than soy.

A. First off, soy may not be a 'perfect food', but in moderation it can have numerous health benefits, for both men and women alike.

It is not entirely right to say that soy has an estrogenic effect. It is a little more complicated than that, and also depends on the organ on which it is exerting its effects. Specific constituents of soy, called isoflavones, are phytoestrogens. Plant source phytoestrogens have a very similar structure to estrogen and do have a mild estrogenic effect in the human body. But, and this is one of the reasons I think it's so great, it can help to decrease estrogen levels when there is too much, and acts to increase it only when an individual is not producing enough. When present in the body isoflavones can bind to estrogen receptor sites. If there is an abundance of estrogen present, this binding acts to lower estrogen levels, as phytoestrogens have a lower estrogenic effect than estrogen itself. By binding, they prohibit the body's own estrogen from being able to bind and therefore prevent the hormone from exerting its full effects in the body. In the case of an individual in menopause, for example, when estrogen is low, phytoestrogens again bind to receptor sites exerting a mild effect. In this case, a little bit of estrogen is better than none at all and can help alleviate symptoms associated with normally decreased levels.

Having explained this process, it makes sense that infants and children, who are supposed to be naturally low in these hormone levels, should be cautious with soy use, as it can increase levels faster or higher than normal, based on age. Particularly in terms of soy based infant formulas, parents need to do their research to decide for themselves whether benefits outweigh the potential side effects. Individuals with thyroid hormone deficiency (hypothyroidism) taking thyroid medication may need to increase their dosage if eating a diet high in soy, as it has been shown to interfere with absorption. Also, individuals having a known iodine deficiency or a diet high very high in goitrogenic foods, may want to be decrease their intake of soy, as in these individuals there is a risk of developing clinical hypothyroidism. Phytic acid levels in soy, are among the highest of any legume and can prevent absorption of certain minerals, including magnesium, calcium, iron and zinc. These levels are reduced somewhat during the fermentation process.

What are the health benefit associated with soy consumption? Soy is high in dietary protein, one of the highest from a non-animal source. Soy has cholesterol lowering effects I has been shown to lower LDL ("bad cholesterol") as well as some effect on lowering triglycerides, without lowering HDL cholesterol levels (the "good cholesterol"). Soy may have an overall protective effect against cancer incidence, although further studies are needed in this area. It has also been widely used to treat symptoms of PMS and menopause.

Individuals worried about soy consumption, in relation to potential health risks, should focus more on environmental estrogens, otherwise known as xenoestrogens. These environmental estrogens are one of the leading causes of breast cancer, and play a part in the development of ovarian and endometrial cancers. They have also been implicated in prostate enlargement and increased risk of prostate cancers in men. Xenoestrogens cause our own estrogen to convert to the cancer causing forms of estrogen in the human body. They can promote infertility by suppressing progesterone, as well as increasing precocious or early puberty in both boys and girls. Xenoestrogens are found in soft plastic products, plastic wrap, medical plastics used in IV bags and oxygen tubing, in pesticides used on a variety of fruits, vegetables, present in dairy and meat, cosmetics containing parabens, bleaching chemicals used on feminine hygiene products, dry cleaning and also present in nail polish and some dark hair dyes. Parabens are widely used in cosmetics, pharmaceuticals and deodorants and they are found in a large percentage of breast tumours. Diets high in hormone containing meats, dairy products and animal fats are also found to significantly increase cancer incidence. Hormone replacement therapy can be a very unhealthy source of exogenous estrogens. Studies show a high correlation between these treatments and breast cancer incidence, risk of blood clots, stroke and coronary heart disease. Even when prescribed with progesterone, the FDA recommends hormone replacement therapy be used at the lowest doses and for the shortest period of time necessary. There is also some debate about the safety of long term oral contraceptive use for these reasons, as well.

Overall, the benefits of soy, in moderation, far outweigh potential harm. Try mixing up your soy sources, getting both fermented (miso, tempeh, etc.) and non-fermented (edamame, soy milk) sources, as they differ slightly in the benefits. More importantly, try to avoid the harmful estrogens, not in soy, but from our environment. Limit use of plastics, use paraben free cosmetics and deodorants and try to keep exogenous estrogen sources, like HRT and contraceptive pill use to a minimum by using natural means of fertility monitoring and herbal alternatives to HRT.

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