Pro's and Con's of TVP
Some of the food supplies available at eFoodsDirect.com include Textured Vegetable Protein (TVP), which is made from soy, as a replacement for meat. Some people have mentioned that they are concerned about the safety of these products. Our research into the subject was inconclusive. Some of that research is posted below so if you are concerned about TVP, please review this information and decide for yourself.
We have made our Liberty Unit available with or without TVP in order to meet your needs.
Steve Shenk
Concerns About Soy (TVP)
For those concerned about estrogens in soy:
Con: Genistein, a major component of soy, was found to disrupt the development of the ovaries in newborn female mice that were given the product. "Although we are not entirely certain about how these animal studies on genistein translate to the human population, there is some reason to be cautious," said Dr. David A. Schwartz, Director of the National Institute of Environmental Health Sciences. "More clinical studies are needed to determine how exposure during critical windows of development can impact human health," he said. Genistein is the primary naturally occurring estrogen in plants (called phytoestrogens) and can mimic the effects of estrogen in the body. The NIEHS researchers previously showed that mice given genistein immediately after birth had irregular menstrual cycles, problems with ovulation, and problems with fertility as they reached adulthood.
A 1986 study in Puerto Rico found that use of soy formula was strongly correlated with premature maturation in girls.
Pro: Soy estrogens are "plant estrogens" or "phytoestrogens". They are found in many plant foods besides soy. Here is an excerpt from an article from the Institute of Food, Science and Technology of the UK.
"Phytoestrogens are naturally occurring phenolic plant compounds, present in foods such as beans, cabbage, soyabean, grains and hops, and are part of a wider class of polyphenols found in all plants. They are structurally similar to the mammalian oestrogen, oestradiol, and have oestrogenic properties. However, their oestrogenic activity is generally much less than that of human oestrogens (oestrogenic activity ranges from 1/500 to 1/1000 of the activity of oestradiol). Hence phytoestrogens can act as anti-oestrogenic agents by blocking the oestrogen receptors and exerting a much weaker oestrogenic effect compared with the hormone. As a consequence it has been suggested that they might partly suppress or inhibit normal oestrogenic activity in oestrogen-responsive tissues such as breast tissue and may reduce the risk of breast cancer. They may, in addition to their endocrine effects, have action on cellular targets which are independent of oestrogen, thereby complicating the prediction of their properties in humans.
Dietary intake of phytoestrogens
Phytoestrogens are found in the seeds, stems, roots or flowers of plants, serving as natural fungicides and acting as part of the plant's defense mechanism against microorganisms. They also are the molecular signals that emanate from the root of leguminous plants that attract specific nitrogen-fixing soil bacteria. The main classes of phytoestrogens are the isoflavones, coumestans and lignans. Isoflavones are receiving a great deal of commercial interest at present; they are found almost exclusively in legumes, the soya bean being the most abundant source. The most important soya isoflavones are genistein and daidzein. Lignans, however are also an important source of phytoestrogens in the UK diet as they are present in most fibre-rich foods."
So, as you can see, phytoestrogens are not only found in many, many plants besides soy, but they are many, many times weaker than human or artificial estrogens.
What many people don't take into consideration when worrying needlessly about soy estrogens (consumed in soy foods, NOT soy supplements), is that there is good evidence of estrogen contamination in meat and dairy products.
Should men eat soy?
Con: "For men, research published in the Lancet found that eating estrogen-like foods such as soy caused lower sperm counts in males. Studies show that men who take in soy protein have up to a 76% decrease in testosterone production." "Male fertility is strongly tied to Zinc, which is necessary for sperm production and testosterone metabolism. Soy contains phytates which are known to interfere with Zinc absorption."
"Recent research at Belfast's Royal Maternity Hospital indicates that isoflavones decrease the ability of a man's sperm to fertilize eggs."
Pro: The birth rate in Asia, where soyfoods are eaten regularly by everyone, should set your mind at rest! There is no evidence that men who eat moderate amounts of soy experience any feminizing effects. There is some evidence that eating soy can enhance fertility in men. The isoflavone genistein may be used to treat male sterility because it affects blood levels of LH [luteinizing hormone], needed for normal sperm production. Soybeans are also high in zinc, a mineral used by the body in the formation of many hormones and which also functions as an antioxidant.
In a study by the Journal of the International Society of Sports Nutrition, researchers found that both soy and whey supplementation resulted in muscle mass increases without negatively affecting serum testosterone levels.
Does soy cause cancer?
Con: There is research that suggests a link between soy and cancer, especially breast cancer. The cause of this potential problem is isoflavones, also called phytoestrogens because they mimic estrogen. Research data, however, are not conclusive, and some studies show just the opposite - under some conditions, soy may help prevent breast cancer.
Pro: One of the factors that perked the interest of cancer researchers some years ago was the striking difference between mortality rates for breast cancer and prostate cancer in the West (North America and Europe) compared to Asian countries, such as China, Japan, the Republic of Korea, and Thailand. In the West your chances of dying of breast or prostrate cancer can be ten to twenty times higher than if you lived in one of these Asian countries.
In men, estrogen plays a part in prostate cancer. Estrogen is a precursor to androgens (male hormones), triggering the production of testosterone. Men with prostate cancer often have higher levels of testosterone than cancer-free men. The estrogen-blocking activities, as well as their tumor-inhibiting qualities, of soy isoflavones may therefore also play a part in preventing prostate cancer in men.
Is soy safe for children?
Con: Soy formulas cause excretion of zinc. Phytic acid in unfermented soy blocks mineral absorption and in fact, has been implicated in crib death. Soy milk is not a good source of calcium. In addition, the huge amount of aluminum found in soy milk is hundreds of times that in mother's milk. The last reason not to use soy milk is the famous plastic effect. There are elements in soybeans which are used in making plastics. Unfermented soybeans will line the digestive track like a plastic film, impeding vitamin absorption, so soy milk as a steady diet is not a good idea.
Pro: It is striking that there have been no reports of hormonal abnormalities in people who were fed soy formula as infants - and this includes millions of people in the past 30 years. In fact, a major study published in the August 2001, Journal of the American Medical Association found that infants fed soy formula grow to be just as healthy as those raised on cow's milk formulas.
I've heard that tofu is fattening - how can that be?
Pro: Tofu has a bad reputation because 50 percent of its calories are from fat. But the total amount of calories in tofu is very low, much lower than equivalent amounts of meat or even avocado or nuts, and much lower than eggs, oil and solid cooking fats.
Can soy affect menstruation and fertility?
Con: "Studies have found that a woman ingesting only 60mg of soy a day gains an average of two and a half days on her cycle. Consuming soy also lowers the levels of both follicle-stimulating hormone (FSH) and luteinizing hormone (LH)." "In essence, soy has a component that mimics estrogen, although a weaker type. When a woman in her childbearing years takes in this estrogen, it interferes with her natural fertility cycle."
Pro: In a 1993 study, women living in a controlled environment for two months had an average increase of two and a half days in the length of time between menstrual periods when they ate soy, which attests to the powerful effect phytoestrogens can have on a woman's body.
Chinese and Japanese women have no trouble with fertility levels, despite daily high soy intake.
Don't non-fermented soyfoods contain "anti-nutrients" which block mineral absorption?
Con: A study conducted more than 30 years ago found that processing soybeans renders the fragile protein content of soy largely ineffective. "Soy is thought by some vegans to be a source of Vitamin B12. But there is research to indicate that Vitamin B12 analogs in soy are not absorbed and may actually increase the body's requirement for the vitamin. Soy also apparently increases the body's requirement for vitamin D. Other research has found that high levels of phytic acid in soy reduce assimilation of calcium, magnesium, copper, iron and zinc."
Pro: Anti-soy writers put forth the theory that "non-fermented soy products contain phytic acid [phytates] which essentially acts as an anti-nutritive food because of its ability to bind with certain nutrients, including iron, zinc, copper and magnesium, thereby inhibiting their absorption." This is a gross over-simplification and misinterpretation of the facts, frankly. However, not only fermenting, but also cooking, sprouting and soaking all destroy some of the phytates. (And soy is not the only food that contains phytates. Wheat bran has higher levels, and all whole grains, legumes, nuts and seeds, and come vegetables, contain them.
Karl Weingartner, a soy specialist at the University of Illinois, found that soy contains just enough phytates to bind the few minerals present in the soy itself and no more. We still absorb all the minerals present in other foods we eat, even foods eaten with soy. Besides, phytates are antioxidants and have numerous healthy effects, from cancer prevention to boosting immunity.
Is it true that eating tofu will give you Alzheimers?
Con: A Hawaii study shows a significant relationship between two or more servings of tofu a week and "accelerated brain aging" and even an association with Alzheimer's disease, says Dr. Lon White. The men were questioned about 27 foods and drinks, with data showing that those who ate more tofu were apt to have impaired mental ability, White said. Tofu was the only consistent link among the men.
Pro: A study conducted in Hawaii by Lon White, M.D., and his associates looked at the diets and the risk of dementia of Japanese men residing in Hawaii. The study found that men who ate the most tofu during their mid-40s to mid-60s were more likely to have dementia and Alzheimer's as they grew older. However, this study is far from conclusive. It measured intake of only 27 foods, and there are many lifestyle factors for which it did not control. Dr. White later said: "It might be that this is totally wrong and the tofu has zip to do with it." (Los Angeles Times, 3/23/2000).
A number of clinical studies have shown that soy and isoflavones from soy are actually beneficial for cognition. "In one study, published in the journal Psychopharmacology in 2001, young adult men and women who ate a high-soy diet experienced substantial improvements in short-term and long-term memory and in mental flexibility. Other studies have found that isoflavone supplements from soy improve cognitive function in postmenopausal women." We know that dementia rates are lower in Asian countries (where soy intake is high) than in western countries. We know that the Japanese lifestyle (with its high soy intake) has long been associated with longer life span and better cognition in old age.
Animal research conducted by Dr. Helen Kim at the University of Alabama at Birmingham suggests that soy, taken in the diet, may actually be protective in the brain. Dr. Kim also noted that there were many differences between the men in Dr. White's study who were high eaters of tofu versus those that were low eaters that could explain why cognitive function differed.
Soyfoods and thyroid
Con: Soy is goitrogenic: it binds iodine, preventing its uptake and use by the thyroid gland, leading to hypothyroidism.
Pro: By Virginia Messina, MPH, RD and Mark Messina, Ph.D.
"Many foods contain goitrogens, compounds that interfere with thyroid function (and in extreme cases can cause an enlarged thyroid, called a goiter). Along with soyfoods, millet, cruciferous vegetables and other foods contain goitrogens. Generally, these foods cause problems only in areas where iodine intake is low since this mineral is important for thyroid function. The effects of iodine deficiency can be made worse if the diet is high in goitrogens.
Although a concern about soy and thyroid function may be news to many vegans, it has actually been a focus of research for more than 70 years. Between 1951 and 1961, this research took on a special importance when about 10 cases of goiter were diagnosed in infants who had been fed infant formula made from soy flour. These old studies form some of the basis for arguments that soy is dangerous for infants. However, the situation for today's soy formula-fed infant is very different. Since the 1960's soy-based infant formula has been made from soy protein isolate (which does not contain the goitrogens component; soy flour formulas did) and it is fortified with iodine. No cases of goiter have been diagnosed in infants fed this formula in the past 40 years.
Nor is there any evidence that consuming soy causes thyroid problems in healthy, well-nourished people who have adequate iodine in their diet. However, it is possible that eating a diet with generous amounts of soyfoods could be a problem for people whose iodine intake is marginal. And that might just include some vegans, since the main sources of iodine in western diets are fish and milk. But the appropriate response to this is not to limit healthful soyfoods; it's to get enough iodine. Vegetables have varying amounts of iodine depending on where they are grown. . . . Foods that can supply iodine to vegan diets are sea vegetables, although contents vary quite a bit. Fortified foods are also a good source. Iodized salt is about the most reliable source. Vegans should be sure that, when they season foods with salt, it is iodized. If this isn't a regular part of your diet, use an iodine supplement.
Conclusion: Soyfoods may contain goitrogenic compounds as do other foods. "There is no evidence that eating soyfoods regularly causes thyroid problems in people who eat a balanced diet. Vegans should make an effort to include adequate sources of iodine in their diet."
Here are some links you may find useful for your own research:
rense.com
NIH News
Bryanna's Vegan Feast
Natural Life Magazine
BellaOnline
About.com:Weight Training