Eating fish such as salmon at least once a week could halve the risk of developing rheumatoid arthritis, a new study has claimed.
The findings stem from a study of more than 32,000 Swedish women and offer another reason to follow the established dietary advice of regularly consuming fish for good health.
Researchers said the benefits of fishy diet are because it is rich in omega-3, which is said to protect both the heart and the brain.
A research team at Sweden's Karolinska Institute analysed the dietary habits of 32,000 women, all of whom were born between 1914 and 1948 and were followed from 2003 to 2010.
Participants provided information on their diet, height, weight, parenthood status and educational achievements, as well as recording the frequency and amounts of various foods they ate, including several types of oily and lean fish.
A total of 205 women were diagnosed with rheumatoid arthritis during the follow-up period and the researchers discovered that a high dietary intake of omega-3 fatty acids - which are found in fish such as salmon and fresh tuna - was associated with a reduced risk of the autoimmune disease.
More than a quarter (27 per cent) of women who developed rheumatoid arthritis ate less than 0.21g of omega-3 fatty acids per day.
Those who ate more than 0.21g per day - approximately one serving of oily fish or four servings of lean fish per week - at two separate time points a decade apart were half as likely to develop rheumatoid arthritis as those who consistently ate less than this.
The findings suggest that women need to eat at least one portion of oily fish every week for several years in order to gain the most benefit.
"Fish body oil and fish liver oil are rich in omega-3 essential fatty acids, which can regulate the body's immune system and fight joint inflammation. We've known for some time that there is good evidence that in people with active arthritis, taking fish oils can reduce the level of inflammation," Professor Alan Silman, medical director of Arthritis Research UK, said.
"What this study suggests is that by taking high levels of fish oils it would appear that it can prevent inflammation from starting in the joint. One of the challenges is that this can mean quite substantial changes in people's diets," said Silman.
The study was published in the journal Annals of the Rheumatic Diseases.
