THURSDAY, March 1 (HealthDay News) -- Researchers are looking for 100,000 female nurses and nursing students to join the long-running Nurses' Health Study, which has yielded insight into a wide range of health issues, such as the benefits of physical activity and whole grains and the dangers of tobacco and trans fats.

The study is open to registered nurses, licensed practical nurses and nursing students between the ages of 20 and 46 who live in the United States or Canada. More than 25,000 have signed up and recruitment will remain open until the study reaches the target of 100,000 new participants. It's the first time nursing students have been eligible.

Since the 1970s, more than 250,000 nurses have participated in the study and completed confidential lifestyle surveys that have helped improve knowledge about nutrition, exercise, cancer, heart disease and many other health issues.

"Nurses were originally recruited for their expertise in accurately reporting health data," lead researcher Dr. Walter Willett, chairman of the nutrition department at the Harvard School of Public Health, said in a school news release.

"Their involvement has been invaluable, and their dedication is remarkable, an astounding 90 percent of them are still enrolled decades later," Willett said. "The new group, NHS3, will allow us to understand how today's lifestyle and environment affect a woman's health in the future."

More information

Learn more about the Nurses' Health Study.