Verdict on Soys Benefits for Menopausal Women Still Out,Mayo Clinic Reports

ROCHESTER, Minn.--According to the November MayoClinic Proceedings, a meta-analysis conducted on soy isoflavones found thatsoy supplementation may not have the same affect as estrogen replacement therapy(ERT) in menopausal women. The research compared soy and estrogens effects onheart disease, breast cancer, bone loss, cognitive function, hormonal changesand skin conditions.

The analysis, conducted by Ann Vincent, M.D., and Lorraine Fitzpatrick, M.D.,led to the suggestion that although some studies cite isoflavones as having acardioprotective effect, other trials indicated a lack of secondary preventionin women with established heart disease.

However, in the Oct. 5 American Heart Associations journal Circulation,researchers found that consuming soy alongside a heart-healthy diet isrecommended for high-risk individuals with elevated total and LDL (bad)cholesterol. The reports authors also did a meta-analysis, focusing on 38clinical trials studying the effects of soy on serum lipids. Results from themeta-analysis found that soy, as a substitute for animal protein, significantlylowered blood levels of total cholesterol, LDL cholesterol and triglycerides,without affecting HDL (good) cholesterol. To support its findings, AHAcited that the Food and Drug Administration approved a health claim and dietaryintake (25 g/d) for soy in Oct. 1999.

This is great for soy manufacturers, that the American Heart Associationendorses the use of soy in a general diet, said a spokesperson for WhiteWave, a soy food and beverage manufacturer. It just shows how the soyindustry is growing at such a fast rate.

However, the Mayo Clinic report questioned soys effect on other conditionsbesides heart health. The authors compiled studies that compared the health ofAmerican and Japanese women to study the relationship between high intakes ofsoy and breast cancer. According to the authors, a high consumption of soy byAsian women may lead to a low occurrence of breast cancer; however,contraindicative studies find that it is a low-fat diet that accounts for thelow cancer rate. Thus, epidemiological studies do not provide a definitiveanswer regarding the ability of soy to protect against breast carcinoma, theauthors noted.

They also suggested that further research is needed on the safety, efficacyand dosage of isoflavones in regards to bone density loss. Furthermore,genistein, an isoflavonoid of soy, had a placebo effect on cognitive decline.Soy supplementation led to contradictory results for easing hot flashes, oneof the major reasons that women seek medical advice regarding ERT, wrote theauthors, adding that these findings highlight a need for larger long-termstudies for definitive conclusions.

Currently, there are no reported adverse effects linked to short- orlong-term use of soy. However,Vincent and Fitzpatrick alluded that a woman whotakes advantage of the wide unrestricted availability of over-the-counter soyisoflavone pills and consumes too much soy may be at risk fordiethylstilbestrol (DES). DES is the result of consuming xenoestrogens, whichare man-made and environmental estrogens similar in molecular structure toisoflavones and other phytoestrogens. Physicians gave xenoestrogens to womenfrom 1948 to 1971 to prevent miscarriage; unfortunately, female fetuses sufferedfrom a rare cancer, clear-cell vaginal adenocarcinoma, which caused infertility.Affected male fetuses suffered decreased sperm counts, testicular cancer andpotential prostate problems.

According to the authors, more research needs to be conducted usingrandomized, placebo-controlled clinical dosage studies. Until then, long-termbenefits of isoflavones with regard to fracture prevention, prevention ofhormone-dependent cancers, attenuation of memory loss and prevention ofcardiovascular disease are currently unknown, Vincent and Fitzpatrickconcluded.

Mark Messina, M.D., co-author of the 1994 book, The Simple Soybean andYour Health, agreed for the most part with the reports findings. Theevidence is very premature for soy, he said. Nonetheless, he notes that thebigger issue is that ERT may put women at risk for breast cancer and that anestrogen alternative may be more appropriate. Soy can be part of thatalternative.

In the meantime, soy product sales are expected to reach $2.6 billion thisyear, u p from $2.1 billion the year prior, according to Soyatech Inc., a BarHarbor, Maine-based consulting firm.

For a copy of the Mayo Clinic report, visit www.mayo.edu/publication/proceedings/2000/nov/7511sc1.pdf.