“Is soy okay to eat?” This is one of the most common questions patients ask me. Soy is widely promoted and widely damned. So what’s the story? Here’s what I’ve concluded.
Most soy sold in the US is genetically modified (GM). The European Union does not permit GM foods to be grown or sold in their countries because studies showed damage in most every organ in animals fed GM foods. The longest studies human studies of the effect of GM foods lasted only 90 days and were performed by the GM industry. The industry has fought scientists wanting to conduct longer-term independent studies. The ones that have been done have not been favorable.
The most common GM foods are soy, corn, Hawaiian papaya, sugar cane, sugar beets, wheat, rice and milk containing recombinant bovine growth hormone (rBGH). GM foods are not labeled in the United States, so if it’s not organic, consider it GM. Yet organic is not a fail-safe. Eating organic will lower but may not eliminate your exposure to GM foods as GM seeds easily spread by wind and wildlife.
Most soy consumed in the US is in the form of soy derivatives, such as soy protein isolates and texturized vegetable protein. This is no different that eating white flour or high fructose corn syrup. These soy derivatives are everywhere in packaged, processed and fast foods. Many vegetarians replace meat with soy derivatives such as veggie burgers, sausages and protein powders. Case reports exist of hormone imbalances in people whose primary protein source is processed soy.
Some raise concerns about anti-nutrients in soy which block the absorption of minerals and other nutrients. Some say this does not appear to be a problem in a diverse minimally processed diet. If this truly is an issue, Asian cultures have gotten around this by eating fermented soy which reduces these anti-nutients. Examples of fermented soy include miso, tempeh, nama shoyu, a fermented soy sauce, and natto. Sea vegetables and sea creatures are a mineral rich part of the traditional Asian diet which would provide additional minerals over and above those blocked by soy.
What about hormones in soy? The estrogen-like compounds called isoflavones in soy are weak. As part of a diverse, minimally processed diet, this does not appear to be a concern. Asian cultures have been eating soy for millennia without feminization of their men. Weak estrogens from plants appear to block stronger estrogens providing an anti-cancer effect.
Soy clearly has elements of pharmaceutical interest such as isoflavones. Can we get these from eating soy foods? It depends. These isoflavones are available from tempeh, a fermented soy product, not from texturized vegetable protein, and to a small degree from soy milk.
So what is the best way to enjoy soy? As part of a diverse, minimally processed diet, favoring fermented soy such as miso, tempeh, nama shoyu and natto, and avoiding soy derivatives. Eat only organic soy.
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