Researchers say fish and marine omega-3s have “no clear protective effect” against RA.

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One expert interviewed by Healthline says a fish-oriented eating plan such as the Mediterranean diet can still help people with autoimmune conditions. Getty Images

A diet rich in seafood — including things such as fish oil and krill supplements — has long been touted for people with rheumatoid arthritis (RA) and similar inflammatory conditions.

Many doctors recommend a diet heavy in fish, or even specific dietary plans such as the Mediterranean diet, for rheumatoid arthritis.

But a recent study in the medical journal BMC Musculoskeletal Disorders says otherwise.

Researchers say that increased dietary intake of fish and marine omega-3 fatty acids doesn’t necessarily have a correlated preventive or protective implication against the effects of RA.

The study used two cohorts of female participants, during which the researchers looked at intake of fish in the diet. These cohorts were made up of 166,013 women.

This was cataloged via food frequency questionnaires first at an initial baseline and then again every four years thereafter.

The scientists leading the study used this information in collaboration with medical record reviews in order to determine the presence and incidence of RA, including symptoms and the serologic status of RA, which is measured through labs and blood draws.

“Prior studies suggest that fish may be protective for rheumatoid arthritis risk perhaps through the anti-inflammatory effect of omega-3 fatty acid, but this relationship has not been clearly established,” the researchers wrote. “Therefore, we investigated fish intake and RA risk by serologic status, age of onset, and smoking using a prospective cohort study with large sample size, repeated measures of dietary intake, and lengthy follow-up.”

During their follow-up, they identified 1,080 RA cases that indicated that an increased fish intake wasn’t, in fact, necessarily associated with all RA cases. The researchers wrote that there was “no clear protective effect” of fish and marine omega-3s against RA.

These researchers also looked at the potential relationship or interactions between fish intake, RA, and smoking.

Studies in the past have shown that smoking increases risk for rheumatoid arthritis.

This portion of the study indicated that fish intake actually reduced the strong association between smoking and RA in patients age 55 and younger.

The authors did mention, however, that this finding still needed more research.

The conflicting research results may make some people with rheumatoid arthritis confused on what to do.

Dr. Nilanjana Bose, an assistant professor at the University of Texas Medical Branch, says what you eat can make a difference.

“A balanced diet is very important for autoimmune diseases,” Bose told Healthline. “A Mediterranean diet (rich in nuts, seeds, fruits, legumes, fish, dairy) and avoiding red meat, carbohydrates, and simple sugars can help reduce inflammation. I feel that omega-3 fatty acids significantly alleviate inflammation and, as such, can be great as additions to the diet, as fatty fish or omega-3 fatty acid capsules can help patients with RA combat their inflammation and risk of cardiovascular disease.”

Bose added that an overall healthy lifestyle is important for people living with autoimmune conditions.

“Prior studies have shown that fatty fish does in fact help RA symptoms,” she said. “Again, this is not a substitute for proper medications but if taken together with medications and a healthy lifestyle, can promote a healthy life.”