WASHINGTON, Aug. 9 /PRNewswire/ -- Diets containing soy foods have contributed to the longevity of people of Okinawa, Japan, who have lived to be 100 years of age or older, according to a report in a Johns Hopkins Medical Institutions publication.

The September issue of the Johns Hopkins Medical Letter, "Health After 50," reports on a study of 600 Okinawan centenarians, or residents who are 100 or older.

The study found that the centenarians shared certain lifestyle factors, one of which was a low-calorie diet that included an abundance of soy foods, vegetables and fish. Other common factors among the group of healthy elderly were regular physical activity, moderate alcohol intake, and "strong belief systems and social networks," the Johns Hopkins Medical Letter said.

Okinawans have 80 percent fewer heart attacks than Americans, the publication said. Residents of the Japanese island also have 75 percent fewer cancers, including breast cancer and cancer of the ovaries in women and prostate cancer in men.

Previous health studies have attributed the role of soy, which is consumed in much greater amounts in Asian diets than in American diets, to better health among Asian residents, particularly in avoiding cancers and cardiovascular diseases.

Okinawa has the highest proportion of centenarians in the world. For every population segment of 100,000 persons in Okinawa, more than 33 are aged 100 years or older.