Paleo Diet and Paleolithic Diet Questions & Answers

Question

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Question:
What is the maximum amount of soy that one can eat without problems? Are there studies that have confirmed a threshold dose in relation to phytoestrogens, phytates, other things? Whether soy is bad or not is not the question, but mainly the quantity.

Backstory:
I got into a discussion with a vegetarian who has vegan leanings, and wishes to eat a meat-free diet. She's not adverse to eating eggs (I think), but she is supplementing their diet with some tofu (maybe 250-500g a week, not a lot, but some) and soy milk (they claim a liter a month or so). I've convinced her that there are bad things in soy, but she wants to know the dose at which problems occur. Essentially, she wants to continue eating soy, and wants to know how much she can eat without the undesired effects to mineral nutrition and her endocrine system. Since she's a fellow scientist, she wants to see some studies, which I am at a loss to provide.

Edit
It's clear to me not to eat any soy, but that fact of the matter is, that she wants to see a study with a convincing case that a certain amount is the maximum amount that one can eat without negative effects. So far I'm just going to try to make the case that there's so much potential for harm, that the best case of action is not to eat any, but any studies showing this would make it a lot easier. It doesn't help that all the studies I can find exposing the negative effects of soy are when it's a regular, or large, part of the diet.

edited Nov 27 2011 at 19:16

asked Nov 27 2011 at 11:21

Bristlebeard
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You mean maximum. The minimum amount is zero. – garymar Nov 27 2011 at 11:32

Thanks for catching that – Bristlebeard Nov 27 2011 at 11:47

Great! Paul Jaminet would say, what's the minimum amount of glucose you can eat without problems? – garymar Nov 27 2011 at 11:57

staceychev · Answer 1 · 2011-11-27 14:12:03Z UTC

If your friend is a scientist and is ensconced in conventional wisdom, she may not listen to paleo/primal/westonprice arguments. I found this website that lists a bunch of scientific references on both sides of the argument. The writer, who is the woman who wrote The Sugar Addicts diet and Potatoes Not Prozac, essentially came to her own conclusion that one serving per day is OK if you're in normal health, and it shouldn't be given to children. I err on a more cautious side and have one serving every couple of months.

http://www.radiantrecovery.com/soy4303html.htm

Chris Antenucci · Answer 2 · 2011-11-27 20:44:53Z UTC

The easy argument to make is that if there's so many studies showing that moderate or large amounts of soy cause so many problems, a small amount will to some degree as well. However, if you're only eating tiny amounts of soy that won't provide you with any health benefits or calories anyway so what's the point? For more proof for your vegetarian friend though, if phytic acid and other anti-nutrients aren't enough, soy also has significant amounts of isoflavones which mimic estrogen, and too much estrogen causes many problems for women. As this writer says, "Soy farming started around 1100 BC in China, where it was used to build soil fertility and feed animals. Soy beans were not considered fit for humans until the Chinese learned to ferment them, which makes them digestible. Asian diets now include fermented soy beans in the form of natto, miso, tamari, and tempeh" http://www.foodrenegade.com/dangers-of-soy/. To directly answer your question about dosage . . . New research shows that eating soy even a couple of times a week can suppress the thyroid, causing Alzheimer’s-like symptoms in younger people. In very sensitive people, even the small amount of soy flour that is in bread can cause problems" http://www.newhealthideas.com/news/soy-is-bad-for-you.

Medical research shows that if you are taking thyroid medication, even a tiny bit of soy can cancel it out. Soy has long been known to cause thyroid enlargement in women and children. If medical researchers knew that, why were we not told?" The reason why it's hard to find studies using small amounts of soy is because most researchers will use an amount they deem large enough to get an intended effect, since they're usually trying to answer the question of what is the minimum amount needed to produce effects, not the maximum. In the article I mentioned above they talk about studies showing even small amounts of soy causing problems, but they didn't provide links to those studies as far as I could tell, but if you search for em I think you can find em.

Milla · Answer 3 · 2011-11-27 11:58:44Z UTC

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http://www.marksdailyapple.com/soy-scrutiny/

check this out. The bottom line is, if you have to have soy, make it small, and fermented.

answered Nov 27 2011 at 11:58

Milla
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	Thanks for the link, but I'm looking for something that gives an actual dosage/amount per day, or something. In other words, no one defines what "small" is. I'm also in need of some sources. – Bristlebeard Nov 27 2011 at 12:21
	All I know of numbers is that for women who have had oestrogen - sensitive breast cancer, no more than 4 servings a week are recommended. If this is considered safe for such women, I'm sure it'd be fine for your friend who wishes to continue enjoying soy...but she shouldn't use it as a primary protein source, it should be the '20' component of the 80/20 principle. Like a cheat. – Milla Nov 27 2011 at 12:44

James · Answer 4 · 2011-11-27 19:08:08Z UTC

I don't recall seeing any studies of the soy minimum doseage and affects (or even GMO vs Non-GMO Soy). One of my dreams when I win zillions in the lottery is making a non-profit foundation to do studies like that. I think I'd call it the SJWTK Foundation. S*** James Wants to Know...

The Quilt · Answer 5 · 2011-11-27 13:49:03Z UTC

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None..................

answered Nov 27 2011 at 13:49

The Quilt
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That's why all those asian cultures with intakes of soy have had so many health problems. Oh wait........... Hmmm........................ Cue convoluted or ambiguous response that fails to address common sense of a dose-response relationship. – conciliator Nov 27 2011 at 19:03

Last I saw, the explanation for that was it wasn't GMO soy. – James Nov 27 2011 at 19:05

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It wasn't gmo soy and it wasn't unfermented soy we see in most processed foods. The Asian cultures that eat soy have it in one fermented form or another since the bacteria break down the allergenic/indigestible molecules in it. – Chris Antenucci Nov 27 2011 at 20:45

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What Chris said...plus they balance it with lots of iodine from seaweed and if you actually look at the intake it asian cultures it isn't that high especially when compared to the soy milk consuming tofu eating vegans and vegetarians in the U.S. – The hacker formerly knownasron Nov 27 2011 at 21:35

Primal Toad · Answer 6 · 2011-11-27 17:02:24Z UTC

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Don't eat any soy at all. What's the point?

answered Nov 27 2011 at 17:02

Primal Toad
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Right on. Given its effects per se, why any? – Dorado Galore Nov 27 2011 at 17:38

raydawg · Answer 7 · 2011-11-27 17:13:29Z UTC

A few months ago, I took one single 1200mg soy lecithin cap as an n=1 since I wanted it for the choline. It immediately killed my morning wood for the next two days.

Haven't touched the stuff since, I'll stick to eggs for choline from now on. The only other ingredient in those caps is glycine, not soy oil, and it claims to be pure lecithin. While it's not supposed to have any of the isoflavones or estrogen, it does.

I can only imagine the damage actual soy milk or tofu would cause.

What’s the maximum amount of soy one can eat without problems?

7 Answers