By Sean Henahan, Access Excellence

SAN ANTONIO- Estrogens derived from soybeans and other plants may offer a promising therapeutic alternative to pharmaceutical estrogens currently in use, reported researchers at the 35th Annual Conference on Cardiovascular Disease Epidemiology and Prevention.

Estrogens derived from mammalian sources are widely used for contraception in pre-menopausal women and to reduce the risk of heart disease and osteoporosis in post-menopausal women. However, there are lingering concerns that estrogen therapy may increase the risk for cancers of the breast and endometrium in some women. Therefore, researchers would like to safer alternative to current estrogen regimens.

Estrogens are also found in more than 300 species of plants. IN preliminary animal studies, soy estrogens have been demonstrated to prevent the development of breast cancer. There is also some indication that women who live in areas where soy is an important component of the diet may have a lower incidence of some cancers. This led researchers at Bowman Gray School of Medicine to conduct a series of diet studies in non-human primates.

"We chose soy protein because of the cross-cultural evidence that Japanese who eat a lot of soy have lower rates of heart disease, breast cancer, endometrial cancer and hip fractures. It look like these plant estrogens may be beneficial in all these diseases that affect women," said Mary Anthony, of Bowman Gray School of Medicine, Winston-Salem, NC.

The researchers randomly assigned 153 macaques to one of three diets: animal protein (casein), soy protein with phytoestrogens intact, or soy protein with phytoestrogens removed. The amounts of fat and cholesterol were the same in all diets. The researchers then measured levels of different types of cholesterol at two, four and six month after beginning the study.

The study showed that levels of LDL and VLDL (two types of 'bad' cholesterol) were highest in the animal protein diet group, slightly lower in the modified soy diet and significantly lower in the group receiving the soy diet with intact phytoestrogens. HDL ('good' cholesterol) levels were highest in the soy-phytoestrogen diet group, lower in the depleted soy diet group and lowest in the animal protein diet group, said Anthony.

"These data suggest that soy protein has a beneficial effect on lipid profiles compared to animal protein, and that at least some of the effect is attributable to the phytoestrogens. IN addition, the data are compatible with cross-cultural studies that show lower rates of coronary heart disease in countries with greater consumption of soy," she reported

While the long term effects of soy on risk of osteoporosis, coronary heart disease and cancer have yet to be determined in western countries, dietary soy supplementation may potentially be a more acceptable method of hormone replacement than current therapies, she noted.

The researchers are also evaluating the safety of phytoestrogens in animal studies. Early results indicate that phytoestrogen consumption is not associated with excessive cell growth in the endometrium.

"At least currently, we have seen no negative effects on the cells like we see with the mammalian estrogens, which are behind the increased endometrial cancer rates," she said.

Transmitted: 95-03-09 16:15:18 EST

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