Numerous medical studies have shown that fatty fish is healthy for the heart. Now researchers say it may also help prevent a debilitating type of arthritis.
Just one serving a week of a fatty fish such as salmon, or four servings a week of a leaner fish such as cod, may cut your risk of developing rheumatoid arthritis by half, according to a study in the Annals of the Rheumatic Diseases.


The study

Researchers reviewed the diets of 32,000 Swedish women who filled out two food questionnaires, one in the late 1980s and another a decade later.

The results

Women who consistently ate at least one serving of fatty fish each week for a period of about 10 years developed rheumatoid arthritis at half the rate of women who ate little or no fish. The researchers say the results held up even after taking lifestyle factors into account such as how often people smoked or drank alcohol.


The science

Researchers speculate that omega-3 fatty acids, the healthy fat in fish, has a protective anti-inflammatory effect on the immune systems of the women who ate more of it.

Rheumatoid arthritis is a chronic condition in which the immune system mistakenly attacks the body's joints. It can trigger pain and eventually destroy cartilage and bone. It's much more common in women than men.
When it comes to overall health, experts recommend people eat two servings of seafood - either fish or shellfish – each week.

"This study is an additional argument to follow that recommendation and to make one of those servings fatty fish," says study author Dr. Alicja Wolk, Professor of Nutritional Epidemiology at the Karolinska Institute in Stockholm, Sweden.


More to digest
Though the study shows promising results, there are a few caveats.
The population in the United States and in many parts of the world is more diverse than Sweden so the results may not be the same elsewhere. Also smoking is known to be a high risk factor for rheumatoid arthritis and though it was controlled for in the study, sometimes it's hard to measure accurately.
Taking fish oil supplements instead of eating fish did not appear to help prevent rheumatoid arthritis. Wolk says this was because there were so few people taking supplements, making it hard to come to any definitive conclusions.

Take home message

Overall, the study was well done and the results are encouraging, says Dr. Jef Lieberman, Rheumatologist and Adjunct Clinical Associate Professor at Emory University in Atlanta.
"I would recommend to patients that one to two servings of fatty fish a week may have some preventative effects on rheumatoid arthritis and should not have any significant downside," says Lieberman.
But both Wolk and Lieberman say: Eat fish in moderation.
"The message is not that you need to be eating fish every day," says Lieberman. "The message is that modest amounts of freshwater or fatty fish may have some potential benefit."