Anywhere from 33% to 75% of people with rheumatoid arthritis (RA) feel that there are some foods that make symptoms, such as stiff and painful joints, better or worse.
However, the scientific evidence is spotty.
"There's no compelling data that generalizes all patients," says Nortin M. Hadler, MD, professor of medicine and microbiology-immunology at the University of North Carolina at Chapel Hill and author of Worried Sick.
"There are multiple trials, but the effects are minimal." Even if some foods do alleviate RA symptoms, it would be hard to sort out individual diet factors, Dr. Hadler adds.
That said, here are six dietary changes that may be worth trying if you have rheumatoid arthritis.
Shed extra pounds
If you're overweight, losing those excess pounds may take some of the pressure off of your joints.
"If I have a patient with RA who's overweight and loses 10 pounds, every time he takes a forceful step forward, that's 30 pounds less on weight-bearing joints [such as the hips and knees]," says Dr. Hadler.
What's more, it may also improve quality of life. A 2006 study found that overweight and normal weight people with RA had a higher quality of life than those who were obese.
Several studies suggest that people with RA may benefit from fish oil supplements, which contain inflammation-fighting omega-3 fatty acids.
RA patients are also at greater risk of cardiovascular disease, and fish oil is thought to be good for the heart too.
However, studies suggest that you need to get 3 grams of omega-3 fatty acids per day (a 4-ounce piece of salmon has a little over 2 grams) for 12 weeks, which could get pricey or the diet hard to maintain.
Make it Mediterranean
In a 2003 Swedish study, people with RA who ate a Mediterranean diet rich in fruits, vegetable, cereals, legumes, and olive oil for three months experienced improved physical functioning and vitality when compared to RA patients who did not.
The effects of the Mediterranean diet on rheumatoid arthritis long-term are still unclear, but including more fruits and vegetables in your diet isn't a bad idea.
Consider a vegetarian diet
At least one study found that people who ate a vegetarian or vegan diet reported an improvement in RA symptoms, including pain score, morning stiffness, and grip strength compared to those who didn't.
However, because these diets are restrictive, many of the participants were unable to maintain them for the yearlong study period.
If you can't give up meat, then at least try to get a few more greens on your plate. The antioxidants, such as those found in green peas, bell peppers, and broccoli, may protect against tissue damage around the joints caused by free radicals.
Check your vitamins
Some evidence suggests certain nutrients may help patients with RA. For example, some studies showed that vitamin E supplements reduce RA joint destruction and pain, while others do not.
Selenium levels are also thought to be too low in some people with RA. However, only one study has found that selenium reduced swollen joints and stiffness, and it also involved fish oil supplementation, so it's difficult to determine if selenium can help reduce RA symptoms.
In addition, some RA patients take methotrexate to slow disease progression. But the drug also inhibits folic acid metabolism and causes a range of side effects, including mouth sores, says Dr. Hadler. He suggests folic acid supplements to decrease these adverse effects.
Find out about allergies
Food allergies, especially to dairy and shrimp, may aggravate rheumatoid arthritis. Some people try elimination diets, which involves removing all potential allergens from the diet and slowly adding these foods back to see if they trigger symptoms.
Studies have tested whether exposing patients to foods that had previously upset their RA consistently worsened their symptoms. "You get a smidgen of a hint that food aggravates symptoms," says Dr. Hadler.
But he explains that there's tremendous variation within any individual's symptoms in a given time period, making it difficult to study the effects of elimination diets.
More from MSN Healthy Living:
- Is it really arthritis? 5 conditions that can fool you
- Can medical marijuana help rheumatoid arthritis?
- 13 important questions about arthritis
- Bing: Arthritis pain relief tips