Soy-based foods may lower sperm count
By Julie Steenhuysen Reuters - Thursday, July 24 12:19 am
CHICAGO (Reuters) - Eating a half serving a day of soy-based foods could be enough to significantly lower a man's sperm count, U.S. researchers said on Wednesday.
The study is the largest in humans to look at the relationship between semen quality and a plant form of the female sex hormone estrogen known as phytoestrogen, which is plentiful in soy-rich foods.
"What we found was men that consume the highest amounts of soy foods in this study had a lower sperm concentration compared to those who did not consume soy foods," said Dr. Jorge Chavarro of the Harvard School of Public Health in Boston, whose study appears in the journal Human Reproduction.
"It was a relatively large difference," Chavarro said in a telephone interview.
Chavarro said studies in animals have linked high consumption of plant-derived estrogens known as isoflavones with infertility, but so far there has been little evidence of their effect in humans.
"We wanted to know if it would affect sperm production and could serve as a marker for the effects on the reproductive system," Chavarro said.
STRIKING DIFFERENCE
Chavarro's team analyzed the intake of 15 soy-based foods in 99 men who went to a fertility clinic between 2000 and 2006.
They were asked how much and how often in the prior three months they had eaten soy-rich foods including: tofu, tempeh, tofu or soy sausages, bacon, burgers and mince, soy milk, cheese, yogurt and ice cream, and other soy products such drinks, powders and energy bars.
Because different foods have different levels of isoflavones in them, the researchers set a standard for serving sizes of particular foods. Then they divided the men into groups according to soy consumption levels. Men in the highest group on average ate half a serving per day.
"In terms of their isoflavone content that is comparable to having one cup of soy milk or one serving of tofu, tempeh or soy burgers every other day," Chavarro said.
The difference was striking. Men in the highest intake category had 41 million sperm per millilitre less than men who ate no soy foods. A normal sperm count ranges from 80 million and 120 million per millilitre, and a sperm count of 20 million per millilitre or below is considered low.
"It suggests soy foods could have some deleterious effect on the reproductive system and especially on sperm production," Chavarro said.
The researchers found the association between soy foods and lower sperm count was stronger in overweight men, which might suggest hormones are playing a role.
"Men who are overweight or obese tend to have higher levels of androgen-produced estrogen. They are converting a male hormone into a female hormone in their fat. The more body fat you have, the more estrogen you produce in your fat," Chavarro said
Reading this reminded me of an article I read a few years ago warning about Soya.
How Safe Is Soya?
by Susun S Weed
Condensation of an article in NewLife Mag, May '96,
by Sally Fallon, M.A. and Mary Enig, Ph.D.
With widespread concern about the possible unhealthy effects of commercial meat and cows' milk many more people than before are using soya products as substitutes for animal products. Soya products are supposed to be high protein, low calorie, devoid of cholesterol, and easy to digest. The authors disagree on most of these counts.
Soybeans were one of the five sacred grains in the Orient according to records dating back to before 1134. Agricultural reports speak frequently of using soybeans in crop rotation (to fix nitrogen and thus improve soil fertility) but there is no indication that soybeans were eaten until fermentation processes were discovered, sometime around 440 BCE. The first soya products eaten by people were tempeh, natto, miso, and shoyu tamari. And it was not until some centuries later (2nd century BCE) that the process of making tofu was discovered.
While it is true that the people of the Orient have relied heavily on tofu as a source of protein for about a thousand years, this is not necessarily by choice nor beneficial. The early Chinese did not eat soybeans, although they did eat other pulses, because they recognized the large quantities of a number of harmful substances which have been well studied scientifically. Some of the most detrimental are potent trypsin inhibitors which block the action of enzymes needed for protein digestion. Soybeans also contain hemagglutinin, which causes red blood cells to lump together.
Soybeans are also high in phytates, an organic acids which blocks the uptake of calcium, magnesium, iron, and especially zinc and contributes to widespread mineral deficiencies. In fact there are more phytates in soybeans than in any other grain, bean, or plant studied and these phytates are remarkably resistant to reduction techniques. Only a long period of fermentation will significantly reduce the phytate content of soybeans. The phytates and other anti-nutrients in soybeans are only partially deactivated during ordinary cooking and can produce gas, reduce protein digestion, and create chronic deficiencies in children.
Another way to moderate the harmful effects of tofu and other unfermented soybean products is to eat tofu with meat or fish, as is traditionally done in the Orient. Vegetarians - especially vegetarian children - who eat tofu and drink soya milk as substitutes for meat and dairy products are at very high risk of loss of bone mass and severe mineral deficiencies. Oriental children who eat soya but no meat, eggs, or dairy often suffer from rickets, stunted growth, and lowered intelligence. Unfermented soya virtually destroys all zinc in the body; and zinc is critical for optimal development and functioning of the brain, nervous system and immune system.
To what do we owe the current upsurge in use of soy products such as TVP and tofu in America? Most of the 140 billion pounds of soybeans raised in the USA every year are made into animal feed or pressed into soya oil.
The soya industry has concentrated for 20 years on creating markets for the byproducts of soya oil manufacture: lecithin and soya protein. But these were generally (and rightly) considered "poverty foods" and rejected by most consumers.
The soy industry recognized that, according to a spokesman: "The quickest way to gain product acceptability in a less affluent market is to have the product consumed on its own merit by those who are more affluent." Thus these soy byproducts have been cleverly marketed to resemble traditional foods: soya milk malteds, soya baby formula, soya yogurt, soya ice cream, soya cheese, soya hot dogs, and so on. Let's face it: these are fake products, not health foods.
The production of soya milk does remove trypsin inhibitors, but at the expense of denaturing the proteins, making them indigestible, of creating a carcinogen, lysinealine, and of reducing the cystine content, an essential amino acid which is already very low in soybeans. The phytate content remains, further deranging the diet.
Soya formula and soya milk is often made with soya protein isolate, an extremely refined product lacking virtually all minerals and vitamins. Many soya formulas sold for infants are rich in trypsin-inhibitors which can stunt growth. And all contain staggering amounts of mineral-depleting phytates. The aluminum content of soya formula is 100 times greater than unprocessed milk. Aluminum has a toxic effects on infants kidneys and may be a cause of Alzheimer's in adults. Soya formula lack three important nutrients found in all milk: cholesterol, which is essential for brain development, and lactose and galactose, which play vital roles in the development and functioning of the nerves.
All is not what it seems with the supposed health benefits of soya. Allergies to soya are at least as common as allergies to milk. Nitrosamines, potent carcinogens often associated with meat, are found in high concentrations in all commercial soya protein foods. Isoflavones, anticarcinogenic sub-stances present in soybeans may have a pro-cancer effect when consumed unfermented. Although soybeans contain large amounts of omega-3 fatty acids, these acids are particularly susceptible to rancidity when subjected to the high heat and pressure require to remove the oil from the bean; such rancidity promotes cancer and heart disease. Additionally, all soya oil is extracted with a solvent, traces of which remain in the oil.
In addition to containing anti-nutrients, soybeans lack these important nutritional elements (found in all animal products): cysteine, vitamin B12, vitamins A and D, and cholesterol. Consumption of unfermented soya products actually increases the body's needs for vitamin D and vitamin B12.
To summarize: traditional fermented soya products, especially when made with organic beans, are beneficial in the diet when combined with rice, sea foods, and fermented vegetables. The value of other soya products is questionable at best, disease causing at worst. The use of soya as a primary protein source is misguided.
