DHA and arthritis.

A diet rich in DHA, one of the two main omega-3 fats in fish oil, may help prevent cartilage loss in people with osteoarthritis.

Researchers studied 472 people who had--or were at high risk for--arthritis in their knees. Those with the highest blood levels of DHA had less cartilage loss (measured by an MRI). The researchers didn't find a link with EPA, the other omega-3 fat in fish oil.

However, people with higher blood levels of arachidonic acid--an omega-6 fat found largely in meat, poultry, fish, and eggs--had more synovitis (but no more cartilage loss) than those with lower levels. Knee synovitis is an inflammation of the membrane that lines and lubricates the knee joint.

What to do: It's too early to know if DHA prevents knee cartilage loss or if arachidonic acid causes knee inflammation. In the meantime, it's worth eating fatty fish like salmon at least twice a week to get a good dose of DHA.

Osteoarthritis Cartilage 20: 382, 2012.