You, too, can help prevent junk science
Thank you, ChristaN, for actual new information instead of anecdotes, panic, conspiracy theories, hypochondria, and platitudes. Very refreshing. Here's some more.
Before I write anything else, I want to express that nothing I write here should be construed as medical advice. I'm not a doctor, and wouldn't advise anyone on nutrition.
I'm writing at such length because I think bad science needs to be directly opposed. What makes bad science bad isn't that it comes to the wrong conclusions, although it does excel at that. Even the conclusions of science done well is often wrong, or at least incomplete, for a variety of reasons. Bad science is science that is biased, that doesn't weigh all the evidence, and especially, it is science that is used to further peoples' pet prejudices. Too many people use scientific papers like religious fanatics use the Bible--as proof texts for their own crackpot notions.
So all of the following is not about whether soy is "good" or "bad", whatever those uselessly simplistic words may mean in this context. It's about whether Kaayla Daniel's article is well-reasoned or not, and whether it includes all the evidence. So far, I say it's not and it doesn't, and I explain why below.
First, resources and responses:
The end notes for the article now appear on the Web athttp://www.mothering.com/10-0-0/html...soy-notes.html
When you see Web site links in this forum that supposedly "prove" that soy "has problems", "is dangerous", or whatever, note that they are almost all from http://soyonlineservice.co.nz
. When everyone with a similar point of view can only ever find one source for their information, you've got to wonder. Furthermore, if you go to the site, you can read still more about revisionist history, "powerful industry" conspiracies, mysterious, vindictive squads of attorneys, "what they don't tell you about" (oh God, not "them" again), and so on. It's propaganda. Some of its conclusions may be true, but it's still propaganda.
In a previous item, EBM writes:
It is unlikely that the article was an attack on vegetarians or vegans. Why not do your own personal research and base your arguments for/against soy on the scientific data? If your research leads you to conclude that soy is harmful, look for an alternative for your diet. If it is not harmful, eat to your hearts content.
This really is not an issue of meat eaters diet vs vegan/vegetarians diet. Sheeesh.
I support this approach. But EBM, this may not be an issue of vegetarians vs. non-vegetarians for you and me, but it seems to be so for the author of the original article.
I decided to write this book because I saw so many clients and friends
suffering from vegetarian and near vegetarian diets. Most often the
chief culprit was soy.
-- Kaayla Daniel, Testosterone Magazine 302,
So I wouldn't be too sure that the article isn't an attack on vegetarianism as much as it is on soy.
Later, EBM writes:
Why is the concept of soy being "potentially" harmful soooooo difficult to swallow?
Personally, I'm not upset about whether soy is "potentially" harmful. I'm upset about Mothering being willing to publish junk science. You can use "science" to prove anything you want if you're willing to pick and choose only those details from only those articles that match your preconceived notions. Read on for an analysis of one--just one--of the over 100 references that Daniel uses in her article.
Starrynight, the PubMed abstract for the study you were talking about is:A maternal vegetarian diet in pregnancy is associated with hypospadias. BJU Int. 2000 Jan;85(1):107-13.
Read the abstract at:http://www.ncbi.nlm.nih.gov/entrez/q..._uids=10619956
You can read the full text of article at the publisher's Web site for free at:http://www.bjui.org/85/1/article/bju436.asp
Take a look at this excerpt from the hypospadias paper (one of Daniel's sources):
The consumption of soya as a substitute for meat is increasing in the UK, partly as a result of the recent problems with beef and partly from concepts of "healthy eating". It is now widely used in the food industry, with the advent of vegetarian-style meals, and it provides the highest concentrations of phytoestrogens (particularly isoflavones) of all edible plant matter [18,21]. However, the estimated daily exposure to exogenous oestrogens by consumers of soya is minimal compared to, e.g. that from oral contraceptives. Such low levels of exposure would perhaps indicate small risks (or benefits), as the biological activity of phytoestrogens is considered to be low. Nevertheless, extended prolonged exposure may cause phytoestrogens in the body to reach biologically significant levels. The possible effects on humans should not be dismissed until more experimental data are available. MacLusky  discussed the more indirect role of phytoestrogens; rather than having a direct oestrogenic effect, they may interact with other factors in the diet and lead to an interference with "normal oestrogen biosynthesis and action".
The comment about potential "biologically significant levels" I find a bit odd, given that the toxicology site (cited below) says that the body metabolizes and eliminates plant phytoestrogens, whereas other, synthetic organic endocrine disruptors, particularly some pesticides, accumulate.
All in all, though, the preceding paragraph from the hypospadias paper reads like good science. The study says that effects are "possible", not present; that phytoestrogens may
interact with other dietary factors and interfere with hormones; that effects on humans shouldn't be ruled out with out more evidence. may
interact... more experimental evidence
. This is how a scientist sounds when speculating about possible explanations for a phenomenon. The author is not making claims, but rather is speculating about what may be worth studying, given what is generally known about hormones. This is what good science sounds like.
Daniel's use of the hypospadias study is revealing. From reading her article, you'd think that the study proved that soy caused hypospadias. What the report actually says (read it for yourself) is that babies of vegetarian mothers in the study had five times the risk of hypospadias than those of non-vegetarian mothers. It speculates
that soy may
be involved, but shows no evidence to the contrary, and makes no claim. Yet Daniel treats it like a slam-dunk.
Other fun facts Daniel somehow missed in the original hypospadias study:
- Dietary phytoestrogens were speculated as only one of the possible causes of the association. Other speculations included increased exposure of the mother to estrogen-disrupting environmental chemicals, particularly pesticides, or a possible, undetermined nutritional deficiency. There is also a 5% probability that the results were due to chance.
- Hypospadias incidence varies widely around the world, and it's not clear why. No evidence was presented that it was associated with local soy consumption. That would be an obvious thing to consider if the scientists were trying to make a case that soy was causative, but it wasn't even mentioned.
- Phytoestrogens have protective effects against several diseases, particularly breast cancer. (Other sources suggest that people who already have hormone-dependent breast cancer may want to avoid phytoestrogen-containing foods because phytoestrogens might encourage cell proliferation.)
- None of the mothers who always ate organic vegetables had a child with hypospadias, but that sample size was too small, and so was not significant.
- Moreover, the article says that food content tables don't provide enough information on phytoestrogen content to measure the quantity the mothers consumed.
- The study even says that they can't link soy to hypospadias, because too few of the women in the study ate enough soy to be statistically significant. Somehow this little detail escaped Daniel's attention.
- The article also mentions in passing that in Asia, "soybean products are a major component of the traditional diet". (Presumably Dr. Daniel will contact these researchers and straighten them out on this point. While doing so, she might also explain to them why Japanese women have over 16 times the concentration of soy metabolism products in their urine as do supposedly soy-infused American women, as this study claims. Might the mighty Urine Industry somehow be involved?)
So, rather than being a damning indictment of soy as a cause of hypospadias, the researchers find a relationship, in one group, between maternal vegetarianism and hypospandias in offspring. They speculate that dietary plant phytoestrogens are one possible cause among many, and say that the issue deserves further study, which it most certainly does. Daniel can't make a case that soy is dangerous, or causes hypospadias, based on this study. At least, not to anyone who has read it, and is paying attention. Yet she tries.
For very accessible background information on endocrine disruptors (which is the major theme of the soy article in Mothering), see the page:http://extoxnet.orst.edu/faqs/pesticide/endocrine.htm
- What chemicals cause endocrine disruption?
Drugs have been specifically designed to treat hormone imbalance in humans. Diethylstilbesterol (DES), a drug with strong estrogenic properties administered to pregnant women until 1971 to prevent miscarriages, is a tragic example. Female children of mothers who took DES during pregnancy have a higher incidence of certain forms of ovarian and vaginal cancer. However, there are many drugs that mimic or otherwise affect hormone balance which are important to modern medicine. Other man made chemicals, with unintentional hormone-like activity include: pesticides such as DDT, vinclozolin, endosulfan, toxaphene, dieldrin, and DBCP, and industrial chemicals and byproducts such as polychlorinated biphenyls (PCBs), dioxins, and phenols. Some of these phenols are breakdown products of surfactants, found in soaps and detergents. Also implicated are heavy metals, plastics, cosmetics, textiles, paints, lubricants. Sewage treatment effluent may contain a variety of natural and man made endocrine disruptors, including natural hormones from animal and human waste.
Currently, there are no standard tests to determine if a chemical is an endocrine disruptor. However, both the Clean Water Act and the Food Quality Protection Act require the EPA to develop test methods by 1999. As many endocrine disruptors are thought to affect sex hormone function, and therefore reproduction, the findings in multigeneration animal studies, currently required for pesticide registration by EPA, can provide strong evidence of the potential for endocrine disruption.
- What natural chemicals have endocrine activity?
There are natural chemicals in plants that have hormone-like activity. These chemicals, mostly phytoestrogens, are found in high levels in broccoli, cauliflower, soybeans, carrots, oats, rice, onions, legumes, apples, potatoes, beer, and coffee. Most phytoestrogens have weak activity (low potency) and people who consume diets rich in these substances may have a reduced risk of developing some hormone related diseases. However, the actual health risk or benefit of a diet rich in plant hormones is largely unknown. Some researchers argue that dietary consumption of plant hormones dwarfs the potential exposure from man made sources. (Emphasis added.)
Another source, this one specifically about phytoestrogens, is from the same site (a Web site about the science of toxins):http://extoxnet.orst.edu/faqs/natural/phytoest.htm
To close on a light note, I did run across a reference to one study that linked high tofu consumption to decreased mental functioning in older men. The study didn't explain whether eating tofu caused mental degeneration, or vice-versa.