Vitamin C and Arthritis
One study has shown vitamin C protects against arthritis and prevents symptoms while another study has shown that vitamin C may worsen arthritis. Why the discrepancy? The studies focus on two different types of arthritis, rheumatoid arthritis (RA) and osteoarthritis (OA), which are different disease processes.
Vitamin C and Osteoarthritis
Osteoarthritis is characterized by a gradual deterioration of the joints, the reason it is also referred to as the wear-and-tear type of arthritis. Study results, which appear in the June 2004 issue of Arthritis & Rheumatism, have shown that the long-term use of vitamin C may worsen the severity of osteoarthritis of the knee.
Researchers analyzed the effect of eight months of low, medium, and high doses of vitamin C in guinea pigs. Guinea pigs, like humans, are not able to synthesize vitamin C for themselves.
The high dose group developed the most severe osteoarthritis of the knee and worst cartilage damage. The researchers in this study concluded that dietary intake of vitamin C should not be supplemented above the current recommended dietary allowance:
- 90 mg per day for men.
- 75 mg. per day for women.
Related Resources - Osteoarthritis
Vitamin C and Rheumatoid Arthritis
Rheumatoid arthritis is an autoimmune disease which leads to inflammation of the lining of the joints, resulting in destruction and deformity of the affected joints. It has been reported in the Annals of the Rheumatic Diseases, that consumption of foods high in vitamin C seem to protect against inflammatory polyarthritis, a form of rheumatoid arthritis involving two or more joints. This study involved more than 23,000 participants who had entered a large cancer study in the U.K. The participants kept food diaries and were arthritis-free at the study onset.
Researchers compared the diets of 73 participants who developed inflammatory polyarthritis during an eight-year period, and 146 who remained arthritis-free. After analysis, researchers concluded that people who developed arthritis ate fewer fruits and vegetables than those who did not develop the disease. Participants who ate the least fruits and vegetables had twice the risk of developing inflammatory arthritis.
There was also a significant difference in how much vitamin C people with arthritis consumed compared to those who did not develop arthritis. Participants who consumed the lowest amounts of vitamin C were three times more likely to develop the arthritic condition than those who consumed the highest amounts of vitamin C. The positive effect of vitamin C on rheumatoid arthritis may be because:
- Vitamin C is a powerful antioxidant, fighting molecules which trigger rheumatoid inflammation.
- Vitamin C serves a role as a cofactor in collagen synthesis, the main protein in joint tissue and bone.
- Vitamin C plays a role in fighting infection and may work to control inflammation which is linked to infection.
- Some believe infection can trigger flares of rheumatoid arthritis.
Related Resources - Rheumatoid Arthritis
Vitamin C and Arthritis: Conclusion
Moderation in vitamin C intake is advised for maintaining healthy bones and joints. Excessive vitamin C intake can be problematic. Eating fruits and vegetables to get daily recommended doses of vitamin C naturally is encouraged.
Related Resources
Sources: Vitamin C Worsens Knee Osteoarthritis in Animal Study, Duke University Medical Center, 6/3/2004, www.dukemednews.org/news/article.php?id=7640; Vitamin C and the risk of developing inflammatory polyarthritis: prospective nested case-control study, Annals of the Rheumatic Diseases, 2004;63:843-847, ard.bmjjournals.com/cgi/content/abstract/63/7/843
