Last Updated: 2002-09-30 17:01:30 -0400 (Reuters Health)

By Suzanne Rostler

NEW YORK (Reuters Health) - Older women with type 2 diabetes who take a daily soy supplement show improvements in cholesterol and insulin levels, according to preliminary study findings.

Although the women took the supplements for only 12 weeks, the finding suggests that soy may reduce the risk of cardiovascular disease, such as heart attack and stroke, in women after menopause. There were no side effects associated with the supplements, researchers report in the October issue of Diabetes Care.

While larger and longer-term studies are needed, the results offer some hope to postmenopausal women with type 2 diabetes, who are up to four times more likely to die of heart disease than their healthy peers.

Recent study findings showing that the long-term risk of hormone replacement therapy (HRT) outweighs the benefits in postmenopausal women left many wondering where to turn for help.

For women with diabetes, the findings were all the more disappointing, Vijay Jayagopal, the study's lead author and a researchers at Hull Royal Infirmary in Hull, UK, told Reuters Health. Type 2 diabetes, the most common form of the disease, typically occurs in adulthood and is often associated with obesity.

"This fall from grace of HRT makes it even more important to focus on alternatives and the use of soy or soy-derived products therefore requires more urgent scrutiny," Jayagopal said in an interview. However, it is too soon to make any recommendations, since it is not clear how much soy is needed to provide cardiovascular protection and in what form it is most effective.

To investigate whether soy protein and isoflavones affected blood glucose (sugar), insulin, and other markers of heart disease risk, the researchers assigned 32 postmenopausal women with type 2 diabetes to take a soy supplement or an inactive pill (placebo) for 12 weeks. The dose of isoflavones--the antioxidant component of soy--was greater than amounts typically consumed in Asian countries, where rates of heart disease are lower and soy is a staple in the diet.

After 2 weeks in which all women consumed their regular diet, the study volunteers switched treatments for the next 12 weeks.

The women took a daily supplement containing 30 grams of soy protein plus 132 milligrams of isoflavones.

The soy supplement was associated with an 8% reduction in fasting insulin and an improvement in long-term blood glucose control, probably through its effect on total and LDL cholesterol, Jayagopal and colleagues conclude. Total cholesterol fell by about 4% and LDL cholesterol fell by 7%, 12 weeks after taking the daily soy supplement.

Chronically elevated levels of insulin, the body's key blood sugar-regulating hormone, raise the risk of both heart disease and exacerbate the effect of diabetes.

There was no effect on weight, blood pressure, HDL ("good") cholesterol, or triglycerides, a type of blood fat associated with heart disease. Similarly, the soy supplement did not appear to influence hormonal levels such as estrogen or testosterone.

"The findings of our study certainly provide an encouraging first step in answering some of the questions and provides hope for many postmenopausal women who are at risk of cardiovascular disease and at present have very few options in the way of therapeutic intervention to reduce this risk," Jayagopal said.

SOURCE: Diabetes Care 2002;25:1709-1714.

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