Every week, it seems, doctors at Harvard and around the country find something new for the health-minded consumer to worry about.

If you don't eat vegetables, you'll get a stroke.

If you take certain prescription drugs, you'll become infertile.

If you don't exercise at least 20 minutes per day, you'll have a heart attack.

These are just a few of the often controversial risk studies produced over the past few years by epidemiologists, or doctors who study statistical relationships. But should anyone listen to the constant barrage, each study with more dire consequences than the last?

One indicator of the tests' importance, it would seem, is their financial impact. And apparently, insurance companies basically ignore the dozens of disease risk studies released by the Medical School each year.

Insurance companies unanimously say that their premiums are based on real past data and proven medical techniques, rather than epidemiologic studies from medical institutions. And even when premiums are reduced or increased, it's hardly a nervous reaction to a single study.

"You may find that your rates could confirm a study or two, but you look at claim experience to determine the rates, so those studies are moot," says Diana Lipps, public relations consultant for the Prudential.

The nature of most of the studies, in which participants fill out questionnaires on their habits and on their incidence of a given illness or condition, means that doctors never actually produce a basis for the increased risk. They can simply associate two groups of data, one of say, eating vegetables, and one of say, suffering strokes.

Nancy M. Kane, assistant professor of management at the School of Public Health, says she doesn't believe insurance companies base premiums on medical study results, but rather on past statistics.

"It has to be a real experience," says Kane. "Actuaries and mathematicians are not so good to say what the future might bring. It's harder to work an actuarial analysis."

Disease risk studies themselves may not affect insurance premiums, but John A. Sanders, general manager of Aetna Health Care Plans for the New England area, says changes in medical technique resulting from medical research results are definitely a part of the actuarial process.

"The key determinant will be if those changes in medical practice would have an effect on medical pricing," he said.

Nancy Peskin, account executive for MetLife, says MetLife has an underwriting policy committee with several medical directors that meets once a month to determine premium changes.

"[The doctors] stay current with the literature, read all the journals, keep up the date with medical developments, and they all have a medical specialty," says Peskin. "They bring to the committee matters which they feel relate to underwriting."