There are so many nutrition myths. How many, you ask? Enough that I can’t possibly do an in-depth rebuttal of them all. Luckily I don’t have to, because there are a lot resources out there. If I can point you towards those resources, and ultimately towards the truth, then I’m happy.
So, let’s have a quick chat about soy. Yes, even soy is under attack. A reader who sent me this picture was understandably concerned by this claim that soy is a cancer-causing, child-killing anti-nutrient.
Other people have already summarized the case against this myth exceedingly well. For a good and thorough read, start with this article and end with this one.
To put in my own three cents about it:
1) Soy – don’t worry about it
Unless you have hypothyroidism, a moderate amount (about 2 servings a day) of soy has not been shown to have any harmful outcomes. In other words, if you are consuming a reasonable daily amount, the image above is completely false; reasonable consumption is not linked to multiple cancers, infertility, breast cancer, or hypothyroidism.
2) Phytoestrogen is not estrogen
The image above reflects concern about the phytoestrogens in soy, and makes inflammatory claims about how much estrogen we get from consuming soy. It’s important to differentiate between phytoestrogens and estrogen. They are not the same thing. Phytoestrogens are 1,000 – 10,000 times LESS potent than estrogen produced by the human body.
3) Phytoestrogen in soy – don’t worry about it
Math nerd alert: Naturally occurring estrogen levels in adult women at peak times are between 10.9 to 40.9 mg/litre. 100 grams of soybeans contain 103.9 mg of phytoestrogen (isoflavones, to be specific), and the average adult has 5 litres of blood.
Plain english: In other words, if all the phytoestrogen in 2 servings of soy were absorbed into the bloodstream, it would equal the highest amount of naturally occurring estrogen in a woman’s body.
Does this concern me? I can see how somebody might be worried about doubling the amount of naturally occurring estrogen in their body, even more so if dealing with infants. Let me remind you, however, of the above point: they are 1,000-10,000 times LESS potent that estrogen produced by the human body!
So unless your infant is really 10,000 times smaller than a normal adult, don’t worry about it.
Even Soy Can Be Processed
Eat soy. But as with all food, eat it in moderation, and make lower processed choices. Don’t assume that an extremely processed soy “burger” is a healthful choice, merely because it’s vegan.
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Thanks for this! I blindly followed the advice that soy should be completely avoided until I started noticing that many health professionals eat it. It got me to wondering…how bad is soy really? Then it also occurred to me, why am I taking advice from people that don’t have real evidence? I still don’t eat a lot of soy, but I am not afraid to do so anymore. I’m finally coming to my senses and just enjoying “everything in moderation.”
Glad the article helped you out! In general, unless someone needs to avoid a food for intolerance or allergy reasons, there probably isn’t a reason to avoid it 100%!
You fail to comment on the fact that soy is now in a great deal of foods and that a large % of the population is allergic to soy. I believe this whole heartly as I am one of them in my small town of just over 5,000 I know of at least 8 who are also allergic to soy. Non of us are happy about all the soy in foods it makes it very hard to find things to eat that don’t hospitalize us once again. We have to read all lables carefully and very often have to make things from scratch which is not easy with busy lives. Down with soy additives in all foods.
Oh yes, the prevalence of soy ingredients in packaged foods is a real challenge for people with a soy allergy!
What exactly does one serving of soy equal? And do we account for the fact that it’s in so many products? I haven’t gone all the way through your site yet, but I’m assuming you encourage a more whole food based diet. What are your thoughts about Soy Lecithin?
Thanks for your comment Jessie.
Yes, I do encourage a more whole food based diet! I think it’s amazing how there are so many foods that we can make ourselves so easily that it’s not necessary to buy pre-packaged. Take salad dressing, for example. When people start to learn how to prepare their own food, it eliminates the question of soy lecithin and other additives.
But, in general, soy lecithin is added in small amounts to food products so it should not be a problem for most people.
A serving of soy would be 150g of tofu or 1/2 cup of edamame beans.
Very interesting article, but you talk only from the perspective of eating soy on a woman’s body. How about its relation to men?
There is a lot of info online stating soy is harmful for men because of that estrogen.
Hi Kevin,
Thank you for your feedback. I’ve linked to a very in-depth article at the end of this comment. It has a great section entitled “feminizing characteristics”. I encourage you to read it for more info. But, in short, adverse effects in men have only been seen in case studies where the man was consuming over 12 servings of soy a day. Again, sticking to 2 servings of soy foods/day appears to be safe!
http://www.veganhealth.org/articles/soy_wth#fem