Older women who eat traditional Japanese soy-based foods on a regular basis face lower risks of heart disease, a doctor who headed a government-sponsored study said Monday.
Soybeans -- eaten as tofu, miso soup or Japanese fermented beans known as "natto" -- have a high amount of isoflavones, a natural source of estrogen similar to the female hormone, the study found.
The risk of heart attacks or strokes for a woman who consumed soy at least five times a week was 0.39 compared with 1 for a woman who consumed the least, it said.
The results were even more striking among women past menopause, with the risk falling to 0.25, said Yoshihiko Kokubo, chief doctor of preventive cardiology at Japan's National Cardiovascular Center.
"The fact that women past menopause had fewer risks of disease show isoflavones play a supportive role in preventing heart attacks," he told AFP.
Estrogen is the most important female hormone that affects women's menstrual cycle and is essential for the healthy functioning of the female body. Estrogen levels decrease sharply once a woman begins menopause.
The study, commissioned by the health ministry, surveyed a total of 40,462 men and women in healthy conditions in rural Japan over 13 years.
The findings would seem to contradict those by the American Heart Association, which last year cautioned there was little direct proof that soy consumption lowered the risk of heart disease.
"Americans' general eating habits, which include more fat intake than Japanese, may explain this difference in results," Kokubo said.
He also acknowledged that his study may have come out differently if it had focused on Japanese who live in major cities who tend to eat more Western food.
Kokubo said the results did not show a direct correlation among men who eat soy, Kokubo said.
"Men tend to drink alcohol and smoke more than women, so that could have hindered the advantages," he said