Diet rich in soy, if adopted early in life, helps protect women's hearts better, according to a Wake Forest School of Medicine study.

Researchers said that lifelong soy consumption causes least atherosclerosis. However, switching to soy diet after menopause produces as much atherosclerosis as a lifelong Western diet. Adopting soy diet after menopause is only helpful when there isn't much atherosclerosis already.

For the study, researchers observed heart conditions of cynomolgus monkeys before and after surgical menopause. They fed premenopausal monkeys protein diets derived either from animal sources or from high-isoflavone soybeans.

Researchers then removed their ovaries. One group of monkeys continued with the soy diet, another changed from animal protein to soy, while the third group stuck with animal protein.

After 34 months, the researchers observed good cholesterol levels in monkeys who consumed soy before and after menopause. And, in those who switched to a soy protein diet after menopause, they displayed enhanced cholesterol levels (with lower total, LDL, and VLDL and higher HDL). But, there were no significant difference found with respect to plaque formation in arteries.

Researchers concluded that monkeys with lifelong soy diet were associated with lower percentage of complicated plaque in their arteries than their peers. However, monkeys also benefitted from postmenopausal switch to soy. Those who had small plaques in the arteries at the time of menopause, experienced reduced progression of plaque in their arteries when they switched to soy diets after menopause.

"This study underscores how important it is for women to get into the best cardiovascular shape they can before menopause. The healthy habits they start then will carry them through the years to come," said NAMS Executive Director Margery Gass, in a press release.

The finding is published in the journal Menopause.