Recruiters with the U.S.-led Nurses' Health Studies, started in 1976, are seeking 100,000 "next generation" subjects in Canada and the United States to expand research into women's health.

More than 250,000 nurses have participated in the studies over the decades, completing confidential lifestyle surveys.

Those surveys have given researchers remarkable access to a virtual mountain of health and lifestyle data — data that has influenced a wide range of what is known about women's health. They have provided insight into nutrition, exercise, cancer, heart disease and many other conditions that have led to important medical advances and knowledge, including the dangers of tobacco and trans fats, and how diet, physical activity and other lifestyle factors can promote better health.

"Nurses were originally recruited for their expertise in accurately reporting health data," Dr. Walter Willett, the studies' lead researcher and chair of the nutrition department at Harvard School of Public Health in Boston, says in a release. "Their involvement has been invaluable, and their dedication is remarkable - an astounding 90 per cent of them are still enrolled, decades later."

The release says a diverse group of women in the "next generation" of the study, called the Nurses' Health Study 3, will allow researchers to understand how lifestyle and environment affect a woman's health in the future.

Female nurses and nursing students between ages 20 and 46 who live in Canada or the U.S. are eligible as recruits. More than 25,000 have already signed up.