Soy Soy: better than just so-so!

I'm happy to announce the return of the Nutrition blogs. Ironically, the Nutrition & Medicine class actually ended a few weeks ago. I'll try to search within the depths of my brain for interesting and helpful facts.

I shall start with soy. The health benefits of soy are pretty incredible... and I'm not just touting them because of my soy-loving Japanese heritage. Soybeans have been touted as the FDA as "heart-healthy", and at one time were linked to decreased total and LDL cholesterol levels (these claims are being denied now, but the health benefits of soy have not). Why? Soybeans are cholesterol-free, are a source of Omega-3's, and more than half of their fat content is polyunsaturated ("good") fat. They're also full of vitamins and minerals. Soybeans contain insoluble fiber, so they're good for your digestion, too. Also, soy protein has 100% biological value--it contains every one of the amino acids our bodies need. It's as complete a source of protein as you can get. Other foods that have "high protein" can actually be missing essential amino acids, so that their biological value is very low. You'd have to mix multiple foods to equal the value of soy (beans and corn, for example, are not complete sources of protein alone--only when combined). And soy's growing in popularity, so you can find soy in products that aren't just tofu, ranging from milk to "soynut butter" to meatless meatballs/patties. When you replace animal products with soy products, you're doing your body a favor: you're replacing high-fat, low-nutrition protein with very nutritious and biologically available protein.

The problem: there's a huge misconception out there about the dangers & benefits of soy--even among medical trainees and professionals. The urban legend goes as such: Soy turns into an estrogen in your body, so if you're a male who doesn't want manboobs or prostate cancer, you should stay away. If you're a female and you want to get pregnant, or want to decrease the unwanted side effects of menopause, you should boost your soy intake because it ups your body's natural estrogen supply.

This myth is WRONG. WRONG WRONG WRONG! It's true that soy is like an estrogen; soy protein contains phytoestrogens ("plant estrogens") that look a lot like but aren't estrogen, and therefore are competitive inhibitors of estrogen. What does that mean? Well: there are estrogen receptors in your body. When estrogen sticks to these receptors, the receptors tickle a bunch of other molecules in your body, which get all happy and do their thang: everything we associate with estrogen. Now, when you introduce soy products, all of a sudden there's a bunch of things that look a lot like estrogen floating around sticking to the estrogen receptors. But since they're not estrogen, the molecules downstream remain untickled. The effects of estrogen are effectively decreased, since it's competing with the soy compounds. So: eating soy to increase estrogen (or avoiding soy to prevent estrogen effects), is contrary to what you want to do.

There is, however, a warranted controversy about soy and reproductive and thyroid health: experiments involving crazy amounts of soy protein in lab rats showed that the soy could be harmful. But the jury's still out, and the heart-healthy benefits of soy have been conclusively shown.

The bottom line: replacing animal products with soy products can be healthy for your heart, and may be preventive of some estrogen-related cancers. To feel secure about your reproductive and thyroid health, just don't overdose on soy--no need to go crazy with it. You don't have to go to GNC and buy a tub of Soy Protein Supplement. Just do a tit-for-tat replacement for some animal-product meals, and snack on edamame instead of fries or chocolate every now and then. And when you do, make sure you're buying soy products that, like the soybeans they're made with, are low in cholesterol and contain real soy protein. And for the dairy intolerant: soy milk is a wonderful alternative.



I hope this was informative and helpful; I found it sort of difficult to write. Feel free to leave questions, and of course to do further research on your own. Don't believe everything you come across; research can be poorly conducted, so take everything with a grain of salt!

Next time: Nutrition-related reasons to love bright colors! Just in time for spring.