Regularly eating fish may reduce a person's risk of developing rheumatoid arthritis (RA), a new study indicates.

RA is a chronic and often painful disease affecting the joints, causing them to become inflamed. An inflamed joint looks swollen and red and appears warm to touch. This inflammation can lead to permanent damage in the joints if the disease is not treated. Around 40,000 people in Ireland are affected.

Swedish scientists looked at the dietary habits of over 32,000 women born between 1914 and 1948. The women completed questionnaires which included details on diet, exercise and smoking.

The scientists were particularly interested in the women's intake of omega-3 polyunsaturated fatty acids (PUFAs), as these have been linked to a reduction in inflammation, which is the main characteristic of RA.

The study found that eating a portion of fatty fish, such as salmon, or four servings of lean fish, such as cod, every week reduced the risk of developing RA by half.

In other words, those who consumed these portions of fish every week had a 52% reduced risk of developing RA compared to those who ate less. However, this fish consumption needs to be kept up for 10 years to see this benefit.

The study also found that regularly eating one or more servings of all types of fish on a weekly basis for a decade reduced the risk of RA by 29% compared to eating less than one portion.

"The inverse association between fish consumption and rheumatoid arthritis can be attributed mainly to its content of long chain omega-3 PUFAs," the team from the Karolinska Institute said.

Details of these findings are published in the journal, Annals of the Rheumatic Diseases.

For more information on RA, see our RA Clinic here