Moderate amounts of soy are likely safe. If you’re eating a ton of soy or pregnant, however, you may expose yourself to dangerous amounts of isoflavones or the weedkiller Roundup.
Soy contains high levels of isoflavones. They're chemicals that can act like or block hormones in the body. Many of the isoflavones in soy are called phytoestrogen: they bond with the same receptors and act similarly to estrogen.
Some have raised concerns that isoflavones in soy will reduce testosterone in men; a handful of studies have supported this conclusion. The literature as a whole, however, does not support the notion that soy generally reduces testosterone. Overloading soy in the diet may drive down testosterone for some, and individual biology plays a role, but moderate consumption of soy has not been shown to have a significant effect on testosterone levels.
Phytoestrogen, however, is dangerous for infants. Animal studies have demonstrated that administration of estrogen can disrupt reproductive and gestational development. You should avoid eating too much soy if you're pregnant. If you have an infant and you're breastfeeding, you should do the same. If you have an infant and you're feeding them formula, do your best to avoid formulas that are manufactured with soy.
Soybeans are largely manufactured by agribusiness giants like Cargill and Monsanto. That doesn't mean that they're bad or unsafe, but if you're worried about ethical consumption and don't want to support those companies you should seek out soy that's locally produced.
Furthermore, soy is commonly produced through massive monoculture. It's genetically modified and sprayed down with Roundup. Monoculture depletes the soil and makes crops susceptible to pestilence and disease. While GM foods are still the center of much controversy, Roundup, is cause for concern. The World Health Organization put out a monograph in March of 2015 declaring that glyphosate, the active ingredient, is likely a carcinogen. If you're buying soy, you may want to seek out varieties that were grown without Roundup.
Some forms of soy are healthier than others. Soy is much healthier when fermented than not. Fermented soy has active cultures, which help to promote a healthy ecosystem within your gut. If you’re eating soy, try for fermented soy products over those that are unfermented.
Possible short-term side effects
- allergic reaction
Possible long-term side effects
- disrupt testosterone levels in some
- disrupt development in the womb and in infants
- interference with reproductive development
- cancer (when sprayed with roundup)
Ingredients to be aware of
- the only complete non-animal protein