Read this in: Dansk
In order to determine the effects of exposure to phytoestrogens, researchers at the Johns Hopkins Children’s Center and the Johns Hopkins Bloomberg School of Public Health randomly assigned pregnant female rats to diets containing none, low and high levels of genistein–the major type of phytoestrogen in soy (Journal of Urology, April 2003 169:1582-1586). The male offspring were thus exposed to genistein indirectly through maternal consumption during pregnancy and lactation. Female rats on the low-genistein diet received between 0.1 and 1.0 mg genistein per day while those on the high-genistein diet received between 6.4 and 23.6 mg genistein per day–somewhat equivalent to the exposure of mothers consuming small amounts and large amounts of soy. Male offspring of mothers on the high-genistein diet exhibited reproductive abnormalities and rats exposed to both the low- and high-genistein diets had shorter testes length, larger prostate mass and lower testosterone concentrations.
The researchers also looked at adult sexual behavior of male offspring. Those exposed to both low and high doses of genistein were less likely to ejaculate after mounting female rats. Most interesting was the fact that males exposed to the low dose were less likely to mount and begin the process of intercourse than males whose mothers received the free or high-genistein diets.
Thus, although adult sperm counts were not affected by exposure to genistein, the male rats exhibited “persistent demasculinization of the male reproductive system.” Ejaculatory behavior was significantly reduced by exposure to genistein. Most significant was the observation that “the low dose led to alterations in male development to a greater degree than the high dose.” This is consistent with other studies reporting “an inverted U-shaped dose response” in males exposed to low and high doses of estrogenic substances.
What this means is that pregnant and nursing mothers should avoid all soy as even a low-dose exposure to genistein caused subtle but significant changes in sexual behavior in male offspring.
The number of children with life-threatening peanut allergies has tripled during the last decade. A new study suggests a link between consumption of soy-based formula and the development of peanut allergies. Scientists at the University of Bristol monitored 14,000 babies in the southwest of England. Among the 49 children who developed a peanut allergy, almost a quarter had consumed soy milk during their first two years. (Less than 5 percent of babies overall receive soy formula in the UK.) According to lead researcher Gideon Lack, “These results suggest that sensitization to peanut may possibly occur. . . as a result of soya exposure.”
We can point out a number of studies in which the conclusions contained in the abstract (the part of the study that doctors most often read) bear no resemblance to the actual experimental results. Examples include the Strom study (funded by the Infant Formula Council) that declared soy formulas “safe” in a great media blast but did not look at thyroid problems or asthma and whose data actually indicated reproductive problems; or the Klein literature study (carried out at a DuPont Children’s Hospital; DuPont owns Protein Technologies, a manufacturer of soy protein isolate) which declared that there is no evidence in the literature of endocrine effects. The Setchell study (also funded by the Infant Formula Council) found estrogen levels up to 22,000 times higher in soy-fed babies but concluded that soy-feeding might prevent baby girls from getting breast cancer. (Setchell made no comment on baby boys!)
An astute reader has discovered another candidate for the “Wrong Conclusion” sweepstakes. A study published in the International Journal of Epidemiology (Oct 2000; 29(5):832-6) contained the following official conclusion: “The present study provides modest support for the preventive role of soy against stomach cancer and heart disease death.” However, only the association with lower heart disease death is correct. What the study actually found was that “Soy protein intake was significantly correlated with stomach cancer mortality rate in men” and “soy product intake estimated as total amount as well as isoflavone and soy protein intake were significantly positively correlated with colorectal cancer mortality rates in both sexes.” In other words, men who consumed lots of soy had more stomach cancer and men and women who consumed lots of soy had more colorectal cancer. These results are especially interesting as soy proponents often claim that Asians have lower rates of colorectal cancer because they eat more soy.
MORE SOY IN OUR FOODS?
The New Zealand government has requested comments on the addition of soy phytosterols to bread, cereal, cereal bars, lowfat milk and lowfat yoghurt. This is the goal–to have soy added to everything.
To further this goal, the soy industry has announced “a national rollout of an educational video promoting soy products in the diet” (The County Today, Eau Clair, WI, December 25, 2002). The video goes with “an entire curriculum to be distributed to schools. The video will show students how to incorporate soy products into the diet and how soy products are used in other functions, including fuel.” Bob Karls, executive director of the Wisconsin Soybean Association and the Wisconsin Soybean Marketing Board said, “We’re really proud of this.” But further remarks hint that the global soy campaign may have hit some snags. “Soy products for human consumption are also being pitched to government decision-makers who donate foods abroad. . . Donated beans could put the industry in a better light.”
Actually, less-than-anticipated sales and surging output are driving down market prices (just-food.com, August 14, 2002). Farmers in major producing countries are seeking nonfood applications for their crops, such as biodiesel fuel, paint, adhesives and even coloring crayons for children. Only 4 percent of today’s soybean crop is used for nonfood purposes. The industry goal is 15-20 percent. We’d like to see it at something like 95 percent, with only 5 percent going towards the production of fermented soyfoods, such as soy sauce and miso.
Listing of Studies Showing Adverse Effects of Soy
As part of our ongoing efforts to keep the public up-to-date on the problems with modern soy foods, we have compiled two lists of studies showing adverse effects of soy: one lists studies showing the toxicity of soy isoflavones (estrogen-like compounds in soy) and the other lists studies showing problems with consumption of soy foods in general. We looked only at studies published in scientific journals–the total was over 150! Very often, the conclusions posted in the abstracts of these studies glossed over negative findings, or even presented these findings as beneficial. Most interesting to us was the large number of recent studies showing carcinogenic and mutagenic effects of soy isoflavones. (We have been accused of citing only older studies and ignoring more recent “positive” findings.) These two lists were submitted to the COT in the UK, and the USDA in the US.
This article appeared in Wise Traditions in Food, Farming and the Healing Arts, the quarterly magazine of the Weston A. Price Foundation, Spring 2003.
Read this in: Dansk