A vegan diet eased joint pain for people with rheumatoid arthritis (RA), according to new research.
Participants consumed a low-fat vegan diet without calorie restrictions in a study by the US-based Physicians Committee for Responsible Medicine.
Rheumatoid arthritis is a long-term condition usually affecting the hands, feet and wrists.
It also causes pain, swelling, stiffness in the joints and eventually leads to joint damage.
The study, published in the American Journal of Lifestyle Medicine, found that participants lost weight - with an average of 14lbs (6.35 kg) - and improved their cholesterol levels.
"A plant-based diet could be the prescription to alleviate joint pain for millions of people suffering from rheumatoid arthritis," said the study's lead author and president of the Physicians Committee, Neal Barnard, MD.
"And all of the side effects, including weight loss and lower cholesterol, are only beneficial."
The 44 participants, who had previously been diagnosed with RA, were split into two groups.
The first group ate a vegan diet and prepared their own food for four weeks.
They then eliminated additional foods for three weeks, then reintroduced the same foods individually over nine weeks.
Group two kept to an unrestricted diet but were asked to take a daily placebo capsule, which had no effect in the study.
The groups then switched diets for 16 weeks.
Researchers calculated each person's Disease Activity Score-28 (DAS28) based on tender joints, swollen joints, and C-reactive protein values, which indicate inflammation in the body.
DAS28 increases with rheumatoid arthritis severity.
During the vegan phase of the study, the patients reported a two point reduction in joint pain, compared to a decrease of 0.3 points in the placebo phase.
The average number of swollen joints decreased from 7.0 to 3.3 in the vegan phase, while that number actually increased from 4.7 to 5 in the placebo phase.
For those who completed the study, people reported their joint pain had improved significantly in the vegan phase, compared with the placebo phase.
In addition to reduced pain and swelling, body weight decreased by about 14 pounds on average on the vegan diet, compared with a gain of about 2 pounds on the placebo diet.
There were also greater reductions in total, LDL, and HDL cholesterol during the vegan phase.
The vegan diet also led to greater decreases in DAS28 in a subanalysis that excluded individuals who increased medications during the study and another subanalysis limited to participants making no medication changes.
