WHEN STUDIES CONFOUND

Since January, major government studies and reports in prominent medical journals have overturned some long-held assumptions about health and diet, questioning the effectiveness of low-fat diets for preventing heart disease among women; the usefulness of vitamin D and calcium supplements; and the benefits of glucosamine and chondroitin for arthritis sufferers. In March, The Wall Street Journal published

Since January, major government studies and reports in prominent medical journals have overturned some long-held assumptions about health and diet, questioning the effectiveness of low-fat diets for preventing heart disease among women; the usefulness of vitamin D and calcium supplements; and the benefits of glucosamine and chondroitin for arthritis sufferers. In March, The Wall Street Journal published a feature titled "The Case Against Vitamins," which cited "a troubling body of research ... beginning to suggest that vitamin supplements may be doing more harm than good."

Conflicting data are nothing new to the scientific community. But they usually stayed within professional boundaries until an overwhelming consensus could be reached. The difference today is that easy access to instant information, and the sheer multitude of competing media outlets, make almost any study, no matter how preliminary or inconclusive, immediately part of the public domain.

"The media coverage of recent studies has certainly created some confusion with customers," said Allison Beadle, nutritionist for H-E-B Central Market, the Austin, Texas-based retailer.

Very large studies like the federal government's Women's Health Initiative - which most recently produced the low-fat, vitamin D and calcium reports - really make a splash when they come out. And, unlike smaller bodies of research, these juggernauts do have the power to recalibrate professional opinions. For their part, supermarket nutritionists say news reports challenging long-held nutritional assumptions provide them with an opportunity to help puzzled shoppers digest all of the new information.

"It seems like almost every week there is either a new study, a new book or a new article that has a new slant on the way we ought or ought not to eat," Beadle said. This is simply due to the fact that consumers are hungry for information and solutions, and the media, publishers, authors and writers know this. So what do they do? They create a product."

Nutritionists consistently say that people would be better off maintaining their weight and getting their daily doses of vitamins through a diet rich in foods like fruits, vegetables and healthful fats. They fear these varying, contradictory news reports can certainly generate unpredictability in the supplement aisle, and possibly even distract consumers from those core messages about healthful eating.