The Great Soy Debate
I'm constantly reading about soy... because based on my own experience as a vegan vegetarian - soy is is the most widely available and inexpensive protein source in the market today. There is a huge debate on the healthiness of this plant - and I'd like to use this as one spot to gather together research on the topic. This msn article I stumbled upon relies heavily on one particular "soy expert"; Mark Messina -- an associate professor at Loma Linda University. I'd have liked to see more links to the studies referenced... but for now this is a starting point.
Here's a link to the article and some quotes of the contents central to the debate.
Soy Debate
Pros of Soy:
Non-fermented whole soy is a complete protein. Because it is an excellent source of protein, soy can replace foods in the diet that are high in saturated fats.
It contains omega-3 fatty acids.
calcium absorption from fortified soymilk is similar to the absorption of calcium from dairy milk
“The amino acid balance is excellent—and for a plant source of protein, that is rare,” says John Erdman, professor of food science and human nutrition at the University of Illinois at Urbana-Champaign. “It is relatively low in saturated fat and it contains no cholesterol. Soy versus other animal sources of protein can reduce serum cholesterol levels [your LDL or “bad” cholesterol]. Some studies show you may even see an elevation of HDL [your “good” cholesterol].”
The American Heart Association recently concluded... soy proteins are thought to lower a person’s bad cholesterol somewhere between 3 percent and 5 percent.
Mark Messina, an associate professor at Loma Linda University who has worked with the National Institutes of Health and the National Cancer Institute, and now consults as a soy expert... "...since every 1 percent decrease in LDL lowers heart disease risk from 2 to 4 percent, even a 3 to 5 percent decrease is relevant.”
“There is very exciting data indicating early soy consumption reduces breast cancer risk,” says Messina. “There have been four epidemiologic studies that have looked at this relationship. The latest study, from the National Cancer Research Institute, found that women who consumed the most amount of soy at 5 to 11 years old were 58 percent less likely to develop breast cancer than women who consumed less soy.”
Cons of Soy:
Soy is one of the top eight allergens, along with milk, egg, peanut, tree nuts, fish, shellfish and wheat.
Soy is a hidden ingredient in so many foods that it can be difficult for those with soy allergies to eat a balanced diet.
[Soy contains phytates and] to some people—phytates do lower iron and zinc absorption.
One point of major debate is the effect of the isoflavones soy contains. The issue with these plant-based estrogens is whether they affect the human body the same way true estrogen would. So far, studies done in rats, using high doses of soy different than that found in whole soy foods, show that isoflavones could have the same effect as estrogen. But ... Human studies indicate that isoflavones do not mimic the negative effect of estrogen unless a cancer tumor is already present in the person eating the soy.
Health organizations in Israel and Great Britain have issued warnings to limit soy consumption for children up to age 18, based on estrogen-mimicking study results in rodents. Soy researchers note, however, that rats and humans process isoflavones differently, and rat studies don’t offer information on how isoflavones affect people.
“There is no human evidence indicting isoflavones [in a supplement or food form] have adverse effects,” says Messina. “Rodents metabolize isoflavones differently than humans and most often these toxicologic studies use pure genistein [a type of isoflavonoid derived from soy products] that is injected. They are not examining soy foods.” Erdman agrees that these studies do not indicate soy is unsafe for humans, given the differences between how rats and people metabolize plant estrogen.
Undecided
The confusion between eating fermented versus non-fermented soy, says Messina, has been discussed a lot online, but lacks any research to back up whether fermented soy is a healthier choice.
The jury is still out on whether soy has any meaningful impact on helping ease menopause symptoms, or on reducing cancer risk for adult soy consumers.
And there have been no human studies that prove soy causes precocious puberty in adolescent girls, a reduction in sex drive for adult men and women, or an increase in risk of thyroid cancer—all health issues red-flagged by anti-soy experts.
genistein in soy may reduce fertility
(article summary)
Phytoestrogen in soy impedes egg, embryo growth, finds mouse study.
"Women who are having difficulty conceiving may want to cut back on their soy consumption after a mouse study reveals that dietary exposure to genistein, a compound found in soy foods, can reduce the odds of a successful pregnancy in multiple ways. The study examined the impact of genistein exposure on oocytes, or eggs, from adult mice and found it can impair oocyte maturation, reduce their potential to become fertilized and hamper the growth of the newly formed embryo. The results reveal how natural compounds like genistein may have both risks – it can act as an endocrine disruptor to affect female reproduction – and benefits - such as protecting the heart. "
Evidence mounts for soy's menopause benefits
Evidence mounts for soy's menopause benefits
Again I'm presenting with conflicting evidence... and I'm getting a little bit further in my reasoning on this in relecting upon my own personal experience.
I've come across several studies that directly correlate the occurence of "inflammation related" diseases to the amount of stress a child goes through prior to adulthood.
The CDC specifically gives statistics and suggestions how to handle in relation to children still going through this process. Here's one such study
Childhood maltreatment predicts adult inflammation in a life-course study
The point is that I definitely had contributing factors in my childhood that were more likely to be the ultimate causal factors in the inflammatory disorders that caused a breakdown of my liver function prior to eating soy.
I speculate that perhaps only soy is contraindicated in those patients that already have inflammatory related liver stress that would cause the liver to not be able to process the toxic effects of the extra estrogenic effects of consuming soy in the first place.
Patients with healthy liver function and who also are experiencing a need to increase estrogenic factors for health related reasons seem to benefit from consuming soy products.
stress and inflammation
That was very interesting--thanks for posting. Fight/Flight leading to inflammation--it's amazing how interconnected our environment, diet, treatment by others, etc. is.
I know a supplement that some women swear by for menopausal symptoms is Black Cohash--but I've also heard that that can have a negative impact on the liver. Perhaps what you're saying above about Childhood maltreatment would apply with those side effects as well.
Soy and your liver
I've been reading about how your body processes excess estrogens and phytoestrogens, and the fact of the matter is that if you have an excess - either due to your own hormonal disfunction or through the phytoestrogens you eat, the burden of processing this through your waste system falls on your liver.
As long as your liver is given the fuel to fully and completely process the waste, you will not suffer a systematic breakdown or health complications from eating soy necessarily. There are some people and medical conditions that I believe soy could most likely benefit if it is used sparingly and used with care.
However, most dieticians I've spoken with do not have a detailed understanding of how soy is processed internally by your system; nor have I came across any that know which foods you should pair it with in order to give your liver support to process any potential estrogen excess.
It's the same concept as "red meat gives you cancer" actually. The books I've read indicate that eating red meat and charred foods actually activates the first part of your liver cleansing process. From there, the second half of the process is vital or the toxins from eating meat are actually more detrimental and they are reabsorbed into your system. It's the imbalance and excess that causes the health problem, not the eating of red meat in the first place.
That's the bad thing about consumerism and cheap food in America. We have a tendency to find something we like; overproduce it and overconsume it because it's too expensive to deviate from the norm.
Most meat eaters I know eat too much meat because it's subsidized, readily available and tasty.
Conversely, I think most vegetarians I know eat too much soy for the same reasons.
liver support
Milk Thistle
I have heard that Milk Thistle facilitates repair liver damage... it is not necessarily something that you'd take to activate one of the phases of the liver's detoxification function.
I haven't heard anything on HepatoThera Fort. It appears to be a product name of a supplement that contains milk thistle as well as specific nutrients used in the liver detoxification cycle. I'll reference my naturopathic medicine book and see which specific phase this supplement supports.
Ok, I've gone out of my way
Ok, I've gone out of my way not to quote this resource because his particular website comes off as gimmicky. The sales pitch there is not hard by any means, but it is more than obvious that the dude is trying to sell things. Nonetheless - there is a great deal of helpful information - he is a PhD for whatever that's worth, and I've found the site incredibly useful and entertaining personally.
I'm noticing under his articles the copyright allows me to quote this here so that you don't have to deal with the format there:
© Copyright 2008 Dr. Joseph Mercola. All Rights Reserved. This content may be copied in full, with copyright, contact, creation and information intact, without specific permission, when used only in a not-for-profit format. If any other use is desired, permission in writing from Dr. Mercola is required.
Disclaimer: The entire contents of this website are based upon the opinions of Dr. Mercola, unless otherwise noted. Individual articles are based upon the opinions of the respective author, who retains copyright as marked. The information on this website is not intended to replace a one-on-one relationship with a qualified health care professional and is not intended as medical advice. It is intended as a sharing of knowledge and information from the research and experience of Dr. Mercola and his community. Dr. Mercola encourages you to make your own health care decisions based upon your research and in partnership with a qualified health care professional.
* These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent any disease.
If you are pregnant, nursing, taking medication, or have a medical condition, consult your physician before using this product.
This is his input on the soy debate in full (if you're curious about investigating his credentials or his site)
Newest Research On Why You Should Avoid Soy
by Sally Fallon & Mary G. Enig, Ph.D.
(excerpts from) Cinderella's Dark Side
The Chinese did not eat unfermented soybeans as they did other legumes such as lentils because the soybean contains large quantities of natural toxins or "antinutrients". First among them are potent enzyme inhibitors that block the action of trypsin and other enzymes needed for protein digestion.
These inhibitors are large, tightly folded proteins that are not completely deactivated during ordinary cooking. They can produce serious gastric distress, reduced protein digestion and chronic deficiencies in amino acid uptake. In test animals, diets high in trypsin inhibitors cause enlargement and pathological conditions of the pancreas, including cancer.14
Soybeans also contain haemagglutinin, a clot-promoting substance that causes red blood cells to clump together.
Trypsin inhibitors and haemagglutinin are growth inhibitors. Weanling rats fed soy containing these antinutrients fail to grow normally. Growth-depressant compounds are deactivated during the process of fermentation, so once the Chinese discovered how to ferment the soybean, they began to incorporate soy foods into their diets.
In precipitated products, enzyme inhibitors concentrate in the soaking liquid rather than in the curd. Thus, in tofu and bean curd, growth depressants are reduced in quantity but not completely eliminated.
Soy also contains goitrogens - substances that depress thyroid function.
Additionally 99% a very large percentage of soy is genetically modified and it also has one of the highest percentages contamination by pesticides of any of our foods.
Soybeans are high in phytic acid, present in the bran or hulls of all seeds. It's a substance that can block the uptake of essential minerals - calcium, magnesium, copper, iron and especially zinc - in the intestinal tract.
Although not a household word, phytic acid has been extensively studied; there are literally hundreds of articles on the effects of phytic acid in the current scientific literature. Scientists are in general agreement that grain- and legume-based diets high in phytates contribute to widespread mineral deficiencies in third world countries.15
Analysis shows that calcium, magnesium, iron and zinc are present in the plant foods eaten in these areas, but the high phytate content of soy- and grain-based diets prevents their absorption.
The soybean has one of the highest phytate levels of any grain or legume that has been studied,16 and the phytates in soy are highly resistant to normal phytate-reducing techniques such as long, slow cooking.17 Only a long period of fermentation will significantly reduce the phytate content of soybeans.
When precipitated soy products like tofu are consumed with meat, the mineral-blocking effects of the phytates are reduced.18 The Japanese traditionally eat a small amount of tofu or miso as part of a mineral-rich fish broth, followed by a serving of meat or fish.
Vegetarians who consume tofu and bean curd as a substitute for meat and dairy products risk severe mineral deficiencies. The results of calcium, magnesium and iron deficiency are well known; those of zinc are less so.
Zinc is called the intelligence mineral because it is needed for optimal development and functioning of the brain and nervous system. It plays a role in protein synthesis and collagen formation; it is involved in the blood-sugar control mechanism and thus protects against diabetes; it is needed for a healthy reproductive system.
Zinc is a key component in numerous vital enzymes and plays a role in the immune system. Phytates found in soy products interfere with zinc absorption more completely than with other minerals.19 Zinc deficiency can cause a "spacey" feeling that some vegetarians may mistake for the "high" of spiritual enlightenment.
Soy Protein Isolate: Not So Friendly
Soy processors have worked hard to get these antinutrients out of the finished product, particularly soy protein isolate (SPI) which is the key ingredient in most soy foods that imitate meat and dairy products, including baby formulas and some brands of soy milk.
SPI is not something you can make in your own kitchen. Production takes place in industrial factories where a slurry of soy beans is first mixed with an alkaline solution to remove fiber, then precipitated and separated using an acid wash and, finally, neutralized in an alkaline solution.
Acid washing in aluminum tanks leaches high levels of aluminum into the final product. The resultant curds are spray- dried at high temperatures to produce a high-protein powder. A final indignity to the original soybean is high-temperature, high-pressure extrusion processing of soy protein isolate to produce textured vegetable protein (TVP).
Much of the trypsin inhibitor content can be removed through high-temperature processing, but not all. Trypsin inhibitor content of soy protein isolate can vary as much as fivefold.21 (In rats, even low-level trypsin inhibitor SPI feeding results in reduced weight gain compared to controls.22)
But high-temperature processing has the unfortunate side-effect of so denaturing the other proteins in soy that they are rendered largely ineffective.23 That's why animals on soy feed need lysine supplements for normal growth.
Nitrites, which are potent carcinogens, are formed during spray-drying, and a toxin called lysinoalanine is formed during alkaline processing.24 Numerous artificial flavorings, particularly MSG, are added to soy protein isolate and textured vegetable protein products to mask their strong "beany" taste and to impart the flavor of meat.25
In feeding experiments, the use of SPI increased requirements for vitamins E, K, D and B12 and created deficiency symptoms of calcium, magnesium, manganese, molybdenum, copper, iron and zinc.26 Phytic acid remaining in these soy products greatly inhibits zinc and iron absorption; test animals fed SPI develop enlarged organs, particularly the pancreas and thyroid gland, and increased deposition of fatty acids in the liver.27
I actually stumbled across this in trying to find the soy - MSG connection.
Apparently when soy is hydrolyzed it creates an amount of MSG in the processed foods. And... MSG sucks.
Preliminary human study on soy and male infertility
Here's another highlight of an MSN article on a recent preliminary study (emphasis added):
Soy may play a role in male infertility for some
Eating half a serving of soy food a day lowers sperm concentrations and may play a role in male infertility, particularly in obese men, Harvard University researchers report.
Chavarro considers the findings preliminary and inconclusive. "It's way too early to say stop eating soy foods," he said. "It's not time to worry about whether you're eating too much soy. There's not enough information to conclusively say that. "
His report was published in the July 24 online edition of the journal Human Reproduction.
Chavarro's team found that men who ate the most soy had 41 million fewer sperm per milliliter of semen compared with men who did not eat soy foods. Normal sperm counts range between 80 million and 120 million per milliliter, according to a press release from the journal, a monthly publication of the European Society for Human Reproduction and Embryology.
In addition, the researchers found that the link between soy and sperm concentration was stronger among overweight and obese men. Overweight and obese men produce more estrogen than thinner men, and soy may increase those estrogen levels even further, they speculated.
Moreover, the link between soy and sperm concentration was strongest in men with higher sperm concentrations. Men who have normal or high sperm counts may be more susceptible to soy foods than men with low sperm counts, Chavarro said.
Infertility expert Dr. Hossein Sadeghi-Nejad, an associate professor of urology at UMDNJ New Jersey Medical School and Hackensack University Medical Center, agreed that soy may be one factor affecting fertility, especially in overweight and obese men.
"When patients are overweight, the fat tissue converts male hormones to more female hormones," Sadeghi-Nejad said. "So, it is possible that the combination of this estrogenic source [soy] and the extra internal estrogen that is caused by the conversion of androgen to estrogen through the fat has a more deleterious effect in that group of patients."
In addition, Sadeghi-Nejad noted that although sperm counts decreased most among men who have the highest counts, that should not affect fertility, since sperm counts were still in the normal range.
Nutritiondata.com article on soy's effect on testosterone
Soy isn't affecting men's hormone levels, but something is...
(article excerpt)
Another industry study seems to put to rest concerns that eating too much soy could affect testosterone levels in men:
They concluded: “These results suggest that consumption of soy foods or isoflavone supplements would not result in the adverse effects associated with lower [testosterone] levels.”
Source: Published online ahead of print
doi:10.1016/j.fertnstert.2009.04.038
“Clinical studies show no effects of soy protein or isoflavones on reproductive hormones in men: results of a meta-analysis”
Authors: J. M. Hamilton-Reeves, G. Vazquez, S. J. Duval,
W. R. Phipps, M. S. Kurzer, and M. J. Messina.
Soy contains weak plant estrogens and many have worried that the increasing popularity of soy products (and the ubiquitous use of soy-based additives and ingredients) could be de-masculinizing our men.
After analyzing the pooled results of 15 different studies, including two which concluded that soy DID affect testosterone levels, researchers say "No significant effects of soy protein or isoflavone intake on testosterone or SHBG [sex hormone-binding globulin] were detected."
In an opinion piece for the New York Times on Sunday, Nicholas Kristoff warns that endocrine disruptors widely used in agriculture and industry are being linked to "evidence of increasing abnormalities among humans, particularly large increases in numbers of genital deformities among newborn boys."
Kristoff cites a statement released by the Endocrine Society as a "wake-up call." According to the paper, endocrine disruptors are affecting both men and women, causing reproductive problems, deformities, cancer, and may even be related to rising obesity rates.
You can avoid soy. You can eat only organic produce. Yet these chemicals are so widely used and so poorly contained that, as Kristoff notes, "everyone is exposed."
Helpful resource on estrogen and cardiovascular health