Today's consumers have a seemingly insatiable appetite for health information. They find it via the Internet, television, radio, newspapers, magazines and, in one of the most convenient forms, newsletters.

Dozens of paid subscription newsletters, generally running eight to 12 pages, are mailed directly to homes from hospitals, universities and prominent doctors. Hundreds more are sent free by organizations such as health plans as a promotional tool.

Competition has been fierce. Over the past decade, as the newsletters have multiplied, the primary players -- usually those published by major medical centers -- have segued into more specialized information, bringing their reputation for reliability to the hot issues of aging, women's health and men's health.

Not only have these publications helped fill the growing demand for more specific information, they've managed to stay relevant as consumers have become more accomplished at extracting news from various sources.

"We realized you couldn't spend enough time talking about breast cancer in a general health publication to meet the needs of some women," said Ed Coburn, publishing director for Harvard Health Publications. "In an eight-page monthly newsletter, you couldn't take three pages talking about breast cancer, because you're not doing a service for the other readers."

It began in the '80s

Dr. Anthony L. Komaroff, editor-in-chief of Harvard Health Publications, a division of the Harvard Medical School, said that in launching the Harvard Women's Health Watch and other specialty newsletters, the editors calculated that there were audiences for generalized publications and more focused newsletters.

The top circulation of the Harvard Health Letter was 432,000 in the early 1990s. Today, it's down to 150,000, but combined circulation of all the publications stands at nearly 700,000, Komaroff said.

"Consumer interests have become more focused over time," said Andrew Thorne, of Englander Publications in Greenwich, Conn. The for-profit publisher has teamed with noted hospitals in recent years, launching several health newsletters.

Two decades ago, Americans had few places to turn for general health information besides their doctors. And doctors didn't always want to share information with their patients, believing that they were ill equipped to understand the complexities of medicine.

In the 1980s, organizations like the People's Medical Society began encouraging consumers to become active participants in their health-care decisions.

That's when a flurry of newsletters made their debuts, bringing information directly to consumers who could read them at their leisure.

The world-renowned Mayo Clinic in Rochester, Minn., began its Mayo Health Letter in 1983; Tufts University's Health & Nutrition Letter made its debut the same year. The Wellness Letter followed from the University of California, Berkeley's School of Public Health in 1984; the Johns Hopkins Medical Letter: Health After 50 in 1989.

Awareness helps

With the material vetted either by the institutions' faculty or advisory boards, the newsletters gave subscribers paying about $30 a year confidence they were getting solid information. At the same time, the newsletters gave the institutions higher profiles.

Today, consumers might receive newsletters from their health plan, their doctors or dentists, and nearby hospitals.

Such information is helpful, but patients should be wary of newsletters created as a commercial marketing ploy, warned Dr. Edward Hill, a family physician in Tupelo, Miss., and chairman of the American Medical Association board. As an example, he cited publications designed to drum up business for bone-density measuring technologies.

"The science of bone density is all over the board right now," Hill said. "The question is who needs to be checked and who doesn't, and I don't think a newsletter can answer that for a patient."

However, newsletters can provide valuable general awareness about conditions such as osteoporosis, doctors agree. When a patient asks a doctor about something he or she has read in a newsletter and that leads to a diagnosis, "there's a very positive health aspect," said Dr. Martin Shapiro, chief of general internal medicine at the University of California, Los Angeles.

Jane E. Allen is a reporter for the Los Angeles Times, a Tribune Publish-ing newspaper.

Well-known newsletters

Of the dozens of health-related newsletters, these are among the oldest and most widely circulated:

* The Mayo Clinic Health Letter has 750,000 subscribers. Mayo also publishes Women's Health Source, with a circulation of 280,000. A subscription is $27. Contact:www. mayohealth.org.

* The University of California, Berkeley Wellness Letter, from UC Berkeley's School of Public Health, focuses on nutrition, fitness and preventive health. A subscription is $28. Contact: www.berkeleywellness.com /

* The Johns Hopkins Medical Letter: Health After 50 has about 300,000 subscribers. A subscription is $28. Contact: www.hopkinsafter50. com.

* Harvard Health Letter has about 150,000 subscribers. Subscriptions are $32 a year. Contact:www.health.harvard.edu / page.cfm?name=subscribe.