Podcast: Play in new window | Download
Summary
On episode 87 of 40+ Fitness, Coach Allan digs into one of nutrition's most polarized debates: is soy good for you? He was prompted by a plant-based podcast he respects recommending soy heavily, which clashed with his own unexamined assumption that soy was something to avoid.
He lays out the case against soy (phytic acid, lectins, plant estrogens called isoflavones, and the fact that 90 percent of US soy is genetically modified) alongside the case for it (soy is the only complete plant-based protein) and works through what the research actually says about cancer, heart disease, and thyroid function.
He lands on a middle path: favor fermented soy like miso and tempeh, and whole forms like edamame and tofu, while avoiding heavily processed soy products like soy protein isolate and fake-meat substitutes.
Links
- https://40plusfitness.com
Key Takeaways
- Phytic acid in soy blocks mineral absorption. As an anti-nutrient, phytic acid binds to iron, zinc, and manganese and prevents your body from absorbing them, which matters most if you already run low on iron.
- Lectins in soy can irritate the gut. These plant defense compounds can inflame the gut lining and contribute to leaky gut, so people with existing gut issues may want to watch their soy intake.
- Isoflavones are plant estrogens, and the cancer research is mixed. Some studies link higher estrogen exposure to increased breast cancer risk, while other studies suggest soy may actually lower the risk of prostate and colon cancer, so the science isn't settled either way.
- Most US soy is genetically modified. About 90 percent of soybeans grown in the United States are GMO, so if that matters to you, you need to know your source, since GMO labeling isn't consistently required.
- Comparisons of soy to processed red meat aren't a fair fight. Studies claiming soy beats meat for heart health typically compare it to processed meat like hot dogs and sausage rather than to quality grass-fed beef, which skews the conclusion.
- Soy may interfere with thyroid medication. The same mineral-binding effect that limits iron absorption can also interfere with thyroid medicine, so anyone on thyroid treatment should talk to their doctor before adding a lot of soy.
- Not all soy is equal: fermentation improves it. Fermented soy like miso and tempeh has enhanced nutritional value compared to unfermented soy, making it the preferred form if you're going to eat soy at all.
- Heavily processed soy products are the ones to avoid. Soy protein isolate, soy chips, and fake-meat patties strip soy so far from its whole-food form that Allan treats them differently than edamame, tofu, or simply made soy milk.
- Vinegar and animal protein can offset some of soy's downsides. Vinegar can help with the mineral absorption issue from phytic acid, and eating animal protein like fish alongside soy, as in a typical Japanese meal, helps the body handle it better.
“What works for Allan doesn't necessarily work for you. What worked in this study doesn't necessarily work for us.”
Coach Allan Misner
Another Episode You May Enjoy
Episode 128 – The China Study Solution With Dr. Thomas Campbell