Culprit found for lower sperm counts: soy (contains estrogen-like chemical)

http://www.guardian.co.uk/science/2008/jul/24/foodtech.medicalresearch

by crocus • 18 years ago

14 10 18 years ago

guardian.co.uk

a10• 18 years ago

Let's see: the Chinese have been eating soy products since the beginning of time, and China is the most populous country on Earth -- I would guess they have a high fertility rate, otherwise the one-child policy would not have been enacted...something seems amiss here...

SwellJoe4• 18 years ago

As I mentioned, tofu does not have these elements, and is the major source of soy protein consumed in Asian nations (boiled young soybeans, called edamame in the west, are eaten as a snack by some folks in Japan and to a lesser degree in other Asian cultures, and I believe there have been a couple of studies in Japan that indicate that men who consume it do have a lower sperm count and lower levels of testosterone, but I may be misremembering).

As is usual in US culture, with it's love of fads and quick-fix solutions, the soybean industry has convinced everyone that soy, in general, is astonishingly healthy. On paper, it actually does look really good: high protein, high fiber content, low fat, low carbohydrates, and no cholesterol (a positive when comparing to other animal-derived protein sources). But, really, soybeans in most forms are quite hard on the body. Since Americans don't, generally, eat tofu, the industry has found other ways to sell its products...as "healthy" additions to breakfast cereal, as a milk alternative, a protein source for meat alternative products like hot dogs, etc. I'm leery of anything that has been pushed that hard by huge corporations (corn being the most obvious example of an industry gone mad with power, and the entirety of the nation suffers for it). But I do loves me some tofu, and eat it all the time. As you note, if the Chinese can eat it for thousands of years without negative impact, I reckon it's safe.

sratner2• 18 years ago

> As you note, if the Chinese can eat it for thousands of years without negative impact, I reckon it's safe.

That's a dangerous statement. Your lifestyle is different to the lifestyle of the Chinese over the past few millennia.

People in northern Europe eat very large quantities of cholesterol-rich foods: salted/cured pig fat, and a thick meat-based jell-o made by boiling pig legs for hours, are two popular dishes in Russia. This diet is not only tolerable, but is recommended during the colder months, as (1) fat is the best energy store we have, and (2) cholesterol reduces the freezing point of lipid cell membranes, helping maintain their fluidity. On the other hand, such a diet would be outright suicidal for an average middle-American.

The same cultures also eat large quantities of heavily-salted preserved vegetables during the winter; the salt is not particularly good for you, but the negatives are outweighed by the benefits of vitamins in the vegetables, which would otherwise be unavailable in the winter months. Again, not recommended for the average American who has access to fresh fruit and vegetables all year.

In Australia, people are hospitalised every year from over-eating after a rich Christmas turkey meal in 40C heat. The tradition evolved in the English winter, where energy demands are higher and digestive systems operate at a greater efficiency.

I do agree with you on the fads. Human metabolism is still sufficiently misunderstood that any claim that advocates particular extreme dietary behaviour will ultimately be proven wrong. The sequence of events usually goes something like this: x provides essential nutrients -> x is added to every product on the market -> scientists claim x causes cancer! -> scientists discover a way to emulate x with y, a healthy alternative! -> y is added to every product on the market -> scientists claim y causes cancer! -> ...

Those claim are generally true, technically. Everything you eat kills you; the trick is balance and moderation.

SwellJoe4• 18 years ago

This has been somewhat understood for sometime, though the science on how phytoestrogens actually react with the human body isn't well understood. The article also doesn't make it clear that there are differences in various soy-based foods. The process that produces tofu (roughly equivalent to making cheese from milk) breaks down the hormone-like compounds, while more raw forms of soy (soy milk, various soy-based meat and dairy alternatives, whole soy beans, etc.) still contain those chemicals.

The interesting thing about soy, to me, is that it is one of the marketing miracles of our time. It was considered inedible in western culture until just the current generation, and now it is considered a "healthy" addition to just about any food. It was used for oil and other raw materials in industry, but not for food. While not as successful as corn (which is simply unavoidable in American foods), the soy industry has integrated its products into the daily diet of almost everyone. While I eat fresh tofu several times a week, I avoid mass-market foods that contain soy, and anything that contains soy in its various "raw" forms (soy flour/meal, soy milk, or whole soy beans). Soy sauce is problematic, as there are "quick ferment" processes used in most cheap soy sauce brands that do not break down the suspect compounds...properly slow fermented soy sauce is generally fine, though.

mhartl• 18 years ago

Do you happen to know if soy protein (as opposed to whole soy flour) has a significant amount of phytoestrogens?

SwellJoe4• 18 years ago

Depends, I guess, on what it's in.

Traditional tempeh is fermented, and so is generally quite friendly. Tofu, as I mentioned, is basically soy milk curd.

But most instances, in US groceries, where something contains "soy protein" it's going to be in the form of soy flour, or soy milk (which is generally soy flour, water, sugar), which, unless fermented for soy sauce and tempeh or made into tofu, has phytoestrogens to one degree or another.

I've never actually found good data on this topic, and it's an area of interest since I'm vegetarian. I enjoy some of the soy-based meat alternatives (Boca Burgers, Morning Star Farms products, etc.), but many contain soy (as well as wheat gluten) in forms that are poorly defined, so I suspect they are subject to this problem. I generally avoid them for that reason. I'd be curious to know what processes do break down those compounds, if any others besides fermentation and turning into tofu do. Simply cooking seemingly does not, however.

MoeDrippins• 18 years ago

I have an odd sense of Schadenfreude here, but I can't quite figure out why.

mooneater• 18 years ago

Culprit found for lower sperm counts: soy (contains estrogen-like chemical)

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