ROCHESTER, MINNESOTA. Rheumatoid arthritis (RA) involves a persistent inflammation of the synovium of the joints eventually leading to destruction of the surrounding bone and cartilage. There is evidence that free radical attacks (oxidative stress) and the presence of pro-inflammatory cytokines are the major culprits and three American universities have just completed a study to determine if antioxidants in the diet or supplements could reduce the risk of RA by combating oxidative stress and inflammation. Their study involved 29,368 middle-aged women who were enrolled in 1986 at which time their diet and supplement usage was ascertained. The women were followed until the end of 1997 at which time 192 cases of RA had been definitely confirmed. The average age at onset was 68 years, range = 57-79 years.
Analysis of diet and supplement intake revealed a strong inverse correlation with dietary intake of the carotenoid, beta-cryptoxanthin. Women with an intake of more than 87 micrograms/day had a 41% lower incidence of RA than did women with an intake of less than 40 micrograms/day. Citrus fruits, particularly oranges are good sources of beta-cryptoxanthin. Zinc supplementation with more than 15 mg/day conferred a statistically significant 61% reduction in RA risk while copper supplementation exhibited a trend for a significant risk reduction. Oddly enough, a high zinc consumption through the diet was associated with a trend towards a greater risk for RA perhaps indicating that zinc-rich food sources tend to contain compounds which increase the risk of RA. Consumption of cruciferous vegetables also showed a protective trend with 3 or more monthly servings of broccoli reducing risk by 35% as compared to consumption of less than 2 servings per month.
The researchers conclude that a high intake of beta-cryptoxanthin and supplemental zinc may materially
reduce the risk of developing rheumatoid arthritis.