The Food and Drug Administration said yesterday that fish and other foods and dietary supplements containing omega-3 fatty acids can claim on their labels that they help reduce the risk of heart disease, even though the supporting scientific evidence is still unfolding.

In recent years, a growing number of studies have prompted many cardiologists to prize omega-3 fatty acids for their apparent ability to protect the heart against inflammation that can lead to blocked arteries and to reduce the risk of often-fatal heartbeat irregularities.

"This new qualified health claim for omega-3 fatty acids should help consumers as they work to improve their health by identifying foods that contain these important compounds," said acting FDA Commissioner Lester M. Crawford, noting that an estimated 500,000 Americans die each year from heart disease.

The decision applies to foods and dietary supplements containing eiscosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) and allows this wording: "Supportive but not conclusive research shows that consumption of EPA and DHA omega-3 fatty acids may reduce the risk of coronary heart disease." The label must also state how many grams of EPA or DHA are contained in one serving. While the amount of DHA and EPA is not required to be listed on the standard nutrition label of food products, consumers will be directed to the ingredients label for more information.

Food manufacturers cannot simply add DHA or EPA to otherwise unhealthful products. With the exception of fish and dietary supplements, the agency requires that foods must be low in cholesterol (less than 20 milligrams per serving) and low in saturated fat (less than one gram per serving and less than 15 percent calories from saturated fat) to add the health claim to their labels.

The FDA also recommended that consumers not exceed more than three grams per day of EPA and DHA. It noted that no more than two grams should come from a dietary supplement, but the FDA did not set a minimum amount of omega-3 fatty acids that must be present in products.

Consumer groups called that confusing. "The key question is how much [EPA and DHA] has to be in a food," said Bruce Silverglade, director of legal affairs for the Center for Science in the Public Interest, which has teamed with Public Citizen, another consumer group, to file a lawsuit against the FDA over qualified health claims. ". . . The tenet of consumer education is to keep it simple. The FDA is making it quite complicated for health-conscious consumers who are trying to improve their diets."

Qualified health claims have been criticized by CSPI and other consumer groups since they were first unveiled a year ago. Unlike the standard health claims approved for such foods as oatmeal or soy, qualified health claims are based on promising, but inconclusive, scientific findings.

The "qualified health" claim for omega-3 fatty acids is the second to be approved by the FDA this year. In April, walnuts received approval for the first qualified health claim from the agency. Sellers of whole and chopped walnuts can claim "supportive but not conclusive research shows that eating 1.5 oz. [a little more than a handful] of walnuts per day as part of a low saturated fat and low cholesterol diet, and not resulting in increased caloric intake, may reduce the risk of coronary heart disease."