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Ask Gerda: Is Soy Good for You or Not?
Gerda Endemann, our senior director of science and research, has a BS in nutrition from UC Berkeley, a PhD in nutritional biochemistry from MIT, and a passion for cherry-picking from our wellness shop. She spends a lot of her time interpreting research—established and emerging. And our wellness routines thank her for this. (Yours will, too. Send us your own questions for Gerda: firstname.lastname@example.org.)
Dear goop, Soy is high in protein, which I like, but my friends say that eating soy is like taking estrogen and that it might cause breast cancer. Is soy good for you or not? —Cora B.
Hi, Cora. Soy is good. There’s no question about the incredible nutritional profile of soy—more on this later—but there has been concern about estrogen-like effects, and about genetic engineering. Edamame, tofu, and soy milk have been associated with good health in East and Southeast Asian cultures for a long time. If these are what you’re eating once or twice a day, great. If processed soy products are making their way into every meal and snack, I’d try to substitute more whole, unprocessed foods. If you’re lucky enough to live in San Francisco, run, don’t walk, to Mamahuhu for the soft-serve vanilla soy ice cream (Chop Suey Sundae) with rose, jasmine, and strawberry jelly.
The idea that soy might contribute to breast cancer has really taken hold, and it’s been hard to convince people otherwise—but I’ll try to. Soy contains phytoestrogens—plant compounds with weak estrogen-like activity—that are called isoflavones. The fear was that the phytoestrogens would cause breast cancer cells to grow, just as estrogen does. However, the evidence is pretty good at this point that eating soy does not promote cancer, and it may even be protective against breast cancer. People who eat the most soy, and the most isoflavones, develop less breast cancer than those eating the least soy. This makes sense, because as it turns out, phytoestrogens don’t have the same effects on breast cells that estrogen does. They may even keep cells from growing. It’s complicated.
People with hot flashes might want some of soy’s estrogenic effects. Isoflavone supplements can help with bone density, cardiovascular health, and hot flashes in menopause. There’s also a good non-soy option: Black cohosh contains bioactive compounds that help with hot flashes. You can get black cohosh in Madame Ovary, goop’s comprehensive multivitamin supplement for before, during, and after menopause. Try this if you don’t want night sweats to wake you up, and let me know if it works as well for you as it does for me.*
Most soy in the US is genetically modified for resistance to herbicides, and some is also engineered for high oleic fat content. There isn’t evidence that the genetically modified soy on the market is harming us, but large, long-term safety studies would be pretty impossible to carry out, so some people are wary. I’ve done genetic engineering, and subtle, unanticipated consequences are not unusual. If this resonates, look for soy foods that are non-GMO or organic, which is always non-GMO.
Nutritionally, soy is amazing: folate, iron, magnesium, potassium, lutein, and choline, plus cholesterol-lowering essential omega-3 and omega-6 fats and the highest-quality protein of any vegetarian source. This means that a gram of protein from soy is about as good as a gram of milk protein for building muscle or making antibodies. (A great non-soy vegan option is Four Sigmatic’s Superfood Protein Packets, with proteins from pea and hemp.) Tofu made with calcium sulfate—look at the ingredient list—is an excellent source of calcium. A true superfood.
Simple soy foods like tofu, edamame, and soy milk contain all of these nutrients. On the other end of the spectrum are textured soy protein and soy oil that have been processed and refined. They contain healthy protein and fat, respectively, but have been stripped of other plant components. As much as you can, stick to eating whole foods.
*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
This article is for informational purposes only. It is not, nor is it intended to be, a substitute for professional medical advice, diagnosis, or treatment and should never be relied upon for specific medical advice. To the extent that this article features the advice of physicians or medical practitioners, the views expressed are the views of the cited expert and do not necessarily represent the views of goop.