To Soy or Not to Soy

People frequentlly ask me about whether or not soy products are beneficial or harmful.  Certainly, there has been much controversy about this topic in the news with seemingly conflicting studies.  Some studies showing the positive impact of soy isoflavones, or phytoestrogens, in reducing menopausal symptoms, cancer risk and heart attacks, have led food companies to make health claims on their products.  At the same time, other studies have indicated that soy products do exactly the opposite, that is, that their estrogenic effect can actually trigger cancer, especially in the breast and prostate.  

So what is a person to believe?

Yesterday, while teaching a holiday cooking class for one of Dr. John McDougall's workshops, I had a chance to hear him talk about this very topic.  Actually, I've heard snippets of his talk before, but am usually in a hurry to pack up my gear and get home.  Yesterday, I decided to stick around and hear the whole thing. He went through the host of studies showing both sides of the soy study, but pointed out one important fact that the general public tends to ignore:  these studies were all conducted with isolated soy proteins.  In other words, they weren't feeding people or rats tofu or tempeh, but large amounts of a chemical substance made by taking soy apart, extracting and isolating one component of it.  Isolated soy protein, or textured vegetable protein, is not something that grows or occurs naturally, but is a thing that is concocted in a laboratory. You can't make isolated soy protein in your kitchen, and it would be difficult to cook with it even if you could buy it.  However, it's increasingly present in food products these days as the star ingredient in most meat analogs and protein bars.  Because of America's obsession with "getting enough protein", this highly processed chemical has been touted as the vegetarian's answer to not withering away. But can you really call these products food?

Most scientific studies are in fact done with components of food, not food itself.  Scientists are forever trying to isolate the very substance in any food that might or might not triggr a particular response.  But we as human beings don't eat that way. Part of the problem in interpreting these studies is that everything is lumped together under the same umbrella called "soy foods", not distinguishing between traditional foods, such as tofu, and isolated soy protein. Some of these studies using large amounts of isolated soy proteins do indeed show some adverse results, including higher risk for cancer, reduced ovulation and sperm count, and testosterone levels. But empirical, population studies of societies that have consumed traditional soy foods for centuries would suggest that they have a positive impact on cancer, heart disease and bone health.  Dr. McDougall states that actually these societies enjoy lower rates of cancer and hear disease not because of a few ounces of tofu or other soy food daily,but beacuse they have a predominantly starch-based diet. Yes, the Japanese and Chinese consume soy products almost on a daily basis, but not in any significant enough quantity to have any impact one way.  In other words, tofu, tempeh, miso, natto, yuba and other traditional soy foods -- that is, soy foods that have been eaten for hundreds, possibly thousands of years, things that you can actually make in your kitchen -- are simply foods.  Not a miracle or panacea.  And not a poison.  Simply food.

And food is what we should eat.  Not isoflavones, or protein, or vitamins, or minerals, or any component of a what was once a whole food but has been taken apart and isolated in a laboratory.  Here's my rule of thumb:  if you can't make it in your kitchen, don't eat it.  (Yes, you can make tofu in your kitchen. You may not want to bother, but you can if you want.  But you couldn't make isolated soy protein in your blender even if you wanted.)

Besides, food just tastes a heck of a lot better than chemicals.