Eating more fish — rather than fish oil supplements — might be associated with lower rheumatoid arthritis disease activity. That’s according to researchers at Columbia and Harvard Universities writing in Arthritis Care & Research.

When they studied 176 RA patients — mostly middle-aged, college-educated White women — the researchers found “statistically and clinically significant” decreases in rheumatoid arthritis disease scores, called DAS28-CRP, among patients who ate fish two or more times per week compared with those who had fish once a month or less often.

[Read more about an anti-inflammatory diet.]

Previously, studies had established that omega-3 fatty acids, which fish oil supplements contain, improved joints. But the researchers note that it wasn’t possible to extrapolate from the studies whether the benefits would result from eating whole fish rather than taking the pills. “We hypothesized that greater fish consumption would be associated with lower RA disease activity scores,” they write.

“Prospective assessment of disease activity in relationship to fish consumption is warranted,” they add.

The researchers examined two categories of fish: “tuna fish, salmon, sardines (cooked or raw including sashimi or sushi)” and “other broiled, steamed, baked or raw fish (trout, sole, halibut, poke, grouper, etc.)”. They excluded fried fish, non-fried shellfish, or mixed fish dishes — such as “stir-fried shrimp or fish with vegetables” — because those are known to have lower omega-3 fatty acid levels.

“The group that ate fish most frequently had some baseline traits that might be associated with improved disease activity, like lower BMI and higher socioeconomic status,” reports Medpage, “but they also had the highest prevalence of smoking and the longest disease duration, making it difficult to see how confounders might affect the relationship between fish consumption and RA disease activity.”

Medscape adds that one limitation of the new research is that it is a cross-sectional analysis, which calls for taking the findings with a grain of salt.

“Dietary studies are notoriously difficult to interpret. With this, it’s a cross-sectional study and cannot prove cause-and-effect clearly,” says Irwin Lim, a rheumatologist in Australia who directs the clinic BJC Health. (The study authors also admit it doesn’t demonstrate cause-and-effect.)

“Saying that, the actual message is an appealing one,” Dr. Lim says. “Fish oils are useful, and this has been shown in previous higher-quality studies. Many people just don’t like the additional pill load or the taste of liquid versions of fish oil.”

Dr. Lim already suggests that patients introduce fish into their diets. “Our preference at our clinic, BJC Health, is where possible to emphasize quality, whole foods, and good nutrition, over the various supplements people buy from the pharmacy,” he says.

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