Monday, August 06, 2012

Too Much Tofu

Someone sent me this link over the weekend:
A New View Of Tofu, New York Times - Well Blog, August 3, 2012

There are some great ideas here, like the peanut ginger sauce, and the technique for baking marinated tofu in the oven on parchment. I'll be trying both of those. I have to say though, these may be beautiful photos but they show too much tofu as a serving:

If you're going to eat tofu, 3 ounces per day is probably a good amount. For tempeh, half that. Just a half cup of soy milk. And edamame, which are green boiled soy beans, no more than half a cup. These amounts provide ~16 mg of phytoestrogens, plant-derived compounds with estrogenic activity. Recall from this study:
"There is a 3-fold increased risk of developing overt hypothyroidism with dietary supplementation of 16 mg soy phytoestrogens with subclinical hypothyroidism."
Or at least make sure you're getting enough iodine.


Dr. Mel said...

This is part of the general criticism of US tofu consumption that I've read in the past--that while Japan and China are cited as healthy consumers of tofu, they actually eat *very little* of it daily or weekly (contrasted with our all-or-nothing approach here). Thanks for the link to the Times article!

Bix said...

Is that so, I didn't know. Well, and Japan's soil is probably fairly replete with iodine. So maybe they have good iodine status.

Dr. Mel said...

Radioactive iodine?

Bix said...

Well, I meant because their soil is close to the sea.

Boy, they're coping with so much.

lemon said...

they are your own recipesreally wonderful ...

Ben P. DaSalt said...

I think you’re being a little overly cautious with the serving size.

“Sixty patients with subclinical hypothyroidism participated in the study.”

They weren’t “normal” participants, they began with a subclinical hypothyroidism diagnosis, and since the study didn’t include any patients with normal thyroids, we don’t have a control group. Graves’ diseases and Hashimoto's are autoimmune disorders, unrelated (as far as we know) to diet.

Also, the soy protein and phytoestrogen was in the form of daily supplements.

With that said,

“However, 16-mg soy phytoestrogen supplementation significantly reduces the insulin resistance, hsCRP, and blood pressure in these patients.”

So that’s worth mentioning again.

There are far more important dietary health concerns than soybeans, especially considering that soybeans as part of a diet tend to mitigate far greater health risks.

Sure, there are animal studies and feeding people with thyroid issues isolated supplements, but the epidemiological data and the risks of soybean consumption in the grand scheme of things doesn’t seem to bear out any clear and present danger.

Were talking about averages here. Even if there is a danger in consuming more than 3 oz of tofu a day, for most people who don’t consume tofu regularly—and no, vegans don’t have to eat tofu everyday either—consuming 6 oz of tofu at one meal isn’t going to blow out anyone’s thyroid. Even three meals of double the about of a suggested tofu limit at 6 oz per serving is only going to net you 18 oz for the week, still 3 oz short than if you consumed 3 oz of tofu everyday for a week.

The effects of high soybean consumption on the thyroid are cumulative, so eating too much soy could be an issue for those who consume a lot though again, for a healthy person, the risk is very, very small. For the average person with an abundance of meal options that can be rotated throughout the week (vegans too), there’s little need to worry about serving size of tofu for fear of thyroid damage.

To quote a source you’ve referenced yourself:

If You're Eating Soy…

Effects of soy… a review...

Thus, collectively the findings provide little evidence that in euthyroid, iodine-replete individuals, soy foods, or isoflavones adversely affect thyroid function. In contrast, some evidence suggests that soy foods, by inhibiting absorption, may increase the dose of thyroid hormone required by hypothyroid patients. However, hypothyroid adults need not avoid soy foods. In addition, there remains a theoretical concern based on in vitro and animal data that in individuals with compromised thyroid function and/or whose iodine intake is marginal soy foods may increase risk of developing clinical hypothyroidism. Therefore, it is important for soy food consumers to make sure their intake of iodine is adequate.”

• Soy for healthy people are fine.
• Soy does not adversely affect thyroid if iodine is good.
• Adequate iodine is important for everyone regardless.
• The concern for people with thyroid problems is theoretical.

With that said. I will acknowledge that a vegan can stack up soy products the same way non-vegans can stack dairy without realizing that it’s the same product, this used to be encouraged by the way by making dairy it’s own “group.”

A vegan day can have soy milk, soy butter, soy yogurt, soy cheese, tofu, and even a soy-based dessert that can add up to a lot of soybean products in one day, however, this is not very different and than a non-vegan consuming cows’ milk, butter, cheese, yogurt, and rich desserts.

My advice for vegans not to eat too much of one food source in various processed forms, is advice I would give to anyone, and not so much because any one food is dangerous, but because it reduces dietary variety and offsets other vegetable whole foods that could be consumed.

(Though there are those long-lived Okinawan’s with their heavy potato diet. Not a processed food, but still, that's a lot of potatoes.)

Bix said...

I'm sticking to a 3-ounce/day serving size.

Even McDougall limits soy:

Soy – Food, Wonder Drug, or Poison?