Dr. Aimee Shunney A Different kind of Doctor

Bad to the Bean
August 26th, 2014


Bad to the Bean: A Pragmatic Discussion on the Condemnation of Soy

Those of you who know me may be surprised to hear me say that I can be a ‘middle of the road’ kind of girl. Despite my many opinions and impassioned stances, I have found that when it comes to health, very few things are black and white.

Case in point: soy.

There has been an incredibly widespread and pervasive attack lobbied against soy in the health industry. The conspiracy theorist in me thinks the dairy lobby plays a large part in this, but I know (or at least I think I know) that the Weston Price folks aren’t on the dairy lobby payroll, and they and their followers would have us believe that soy will singlehandedly kill us all. So maybe big dairy isn’t behind the soy-slinging. Regardless, those who believe that soy is harmful say that it contains estrogen and causes cancer, that it will render your thyroid useless, that it will make it impossible for your body to absorb minerals and that it is an industrialized waste product (!).

All this despite the scientific and epidemiological data (of which there is a lot) that shows soy to be an excellent nutritional source of many important nutrients including protein, fiber, minerals, B vitamins, essential fatty acids, isoflavones, phytosterols and lecithin. Some of it’s’ most important well-documented effects include lowering cholesterol, promoting hormone balance, decreasing cancer risk and slowing cancer growth.

I feel like a more pragmatic approach needs to be adopted here.

My (Brief) Responses to the Most Common Arguments against Soy Consumption:

  1. Soy does not contain estrogen. It contains isoflavones that are called ‘phytoestrogens’. These components can fit in to our own estrogen receptors and, since they have about 1/1000 the estrogen effect of our own estrogen, their presence lowers the overall estrogen effect in the body. This is why soy can be a healthful food for hormonal balance throughout the lifespan and why it can help prevent cancers and/or slow cancer growth that is sensitive to estrogen, like breast and prostate cancer. Other anticancer effects of soy include its’ ability to promote apoptosis (cell death for ‘dysfunctional’ cells) and inhibit angiogenesis (growth of blood vessels to increase blood supply to tumors).
  2. There have been no human studies that have shown that soy foods can cause any increase in cancer risk. There are some animal studies out there using high dose isoflavone supplements that have mixed results, but none of them have great methodology and, in light of all the POSITIVE human data on soy and cancer risk, they just don’t come across as impressive enough to stop eating soy – maybe soy supplements – but not soy foods.
  3. Soy will not render your thyroid useless. Soy can act as a goitrogen which means that it can compete with Iodine in your body. Your thyroid needs Iodine to create thyroid hormone and without it, your thyroid function will decrease. But guess what? This should not be a problem unless you have a coexisting Iodine deficiency (which is actually very common in this country). Look at all the Asian countries that eat much larger amounts of soy than we do and seem to do quite well (much lower breast cancer rates, for example). What else do they eat a lot of? Seaweed! Seaweed and seafood are your best sources of Iodine and packed full of minerals, so learn how to include dulse/kelp flakes, kombu and nori in your diet. If that’s not enough to ease your mind, cooking goitrogenic foods neutralizes the vast majority of these anti-thyroid effects. And if I’m not mistaken, most soy that we eat is cooked.
  4. Soy (and all legumes) contains phytic acid that binds minerals. Fermentation greatly reduces phytic acid and makes this a non-issue. It’s really a non-issue, anyway. Many foods contain chemicals that would be harmful if you ate them all day. You would be hard-pressed to eat enough soy foods to significantly block mineral absorption. There are much better ways to ensure adequate mineral absorption than avoiding phytates in soy (see above).

Here’s What I DON’T like about Soy:

  1. We turn in into junk food – soy cold cuts, soy jerky, etc., it’s ubiquitous in prepared foods and of all the soy eaten in this country, the majority is refined unfermented tofu or bean curd and ‘soy substitute’ junk foods. Soy is not a health food in this context.
  2. It’s challenging to find 100% organic non-GMO soy. USDA Organic (which means at least 95% organic) is not enough to assure you that your soy is non-GMO. Know your brands!
  3. I do not recommend isolated isoflavone soy supplements in my private practice at this time as I feel like the jury is still out on their benefit and risk. I feel quite confident recommending soy foods (see below) – even to those with hormone-related cancers (although I would limit them to 4-5 servings/week). An important exception would be a cancer survivor taking a drug (ie: tamoxifen) that depletes the body of estrogen. In these situations, soy should be avoided.
  4. Many people have allergies or sensitivities to soy and don’t digest it well. Again, soy is not a health food in this context.

How to Eat Soy

  1. As a varied part of your healthful whole foods diet. Vegetarians and vegans – do not eat soy 3-4X/day. There is nothing except fruits and vegetables that you should eat that often. Variety is the spice of life, after all.
  2. Focus on cooked soy to neutralize goitrogens, fermented soy to maximize mineral absorption (tempeh, miso, natto) and whole soy for nutritional density (edamame, soy nuts). Limit your intake of ‘soy substitute’ foods and tofu. Tofu itself isn’t bad, it’s just not terribly nutritious and you are better served by eating other types of soy described here.
  3. Do your best to consume 100% organic non-GMO soy.
  4. While I am not a huge fan of soy infant formula (I would personally prefer organic cow or goat dairy if breastfeeding is not an option), sometimes allergies require this and I don’t think it’s overly problematic. Soy has an excellent protein profile and it’s very nutritious. It’s worth mentioning, though, that many babies I see in my practice have allergies to dairy and soy. Keep your eyes open when first introducing soy to a baby (as with any food). FYI, soy is thought to have it’s MAXIMUM benefit to the breast tissue when given to teenage girls.

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Dr. Aimée Shunney