LONG BEACH, CALIF. — Antioxidants have been taking a back seat to fatty acids in research on the dietary factors that may influence systemic lupus erythematosus, but an overview of the literature suggests that vitamins may affect disease progression more than lipids.
That is the tentative conclusion of Glinda Cooper, Ph.D., who presented the results of a review of the potential dietary influences on systemic lupus erythematosus (SLE) at the annual meeting of the American College of Nutrition.
“What is it that affects the expression of these self-antigens” associated with disease? Dr. Cooper asked. Because fatty acids have been shown to influence inflammation, they have been studied much more extensively than any other dietary component, she noted.
Over the past decade, one hypothesis has been that omega-3 fatty acids protect against inflammatory responses in lupus. Fatty acids are precursors to prostaglandins, which either inhibit or promote inflammation, she explained. However, a review of the literature shows “we're just not seeing much” in terms of a demonstrated effect from their intake, said Dr. Cooper, principal investigator of the Carolina Lupus Study at the National Institute of Environmental Health Sciences, Research Triangle Park, N.C.
Neither the Nurses' Health Study nor an observational study of 200 patients with SLE showed an association with fatty acid ingestion. In the latter, however, there was a link between decreased disease activity and increases in vitamins C, E, and A, she said. Some investigations are showing that vitamin C, along with other antioxidants, may help curb expression of symptoms.
A study done by researchers at Johns Hopkins University, Baltimore, found lower blood levels of β-carotene, α-tocopherol, and retinol in blood donors who developed SLE 2–15 years later, compared with donors matched for race, age, and sex. This was a small study, but the results bear more investigation, she said.
Studies in mice have associated the course of disease and the level of fatty acids in the diet, Dr. Cooper said. But in human studies, “there is a disconnect.” It may be that other factors enhance the influence of fatty acids, or that the dietary source from which they originate has some kind of effect on how well they are used by the body.