The antioxidant vitamins A, C, E and selenium in the treatment of arthritis: a systematic review of randomized clinical trials

Canter, P. H.
Wider, B.
Ernst, E.

Department of Complementary Medicine, Peninsula Medical School, Universities of Exeter and Plymouth, 25 Victoria Park Road, Exeter EX2 4NT, UK

Submitted 16 January 2007; revised version accepted 26 March 2007.

Correspondence to: P. H. Canter, Department of Complementary Medicine, Peninsula Medical School, Universities of Exeter and Plymouth, 25 Victoria Park Road, Exeter EX2 4NT, UK. E-mail: [email protected]

Rheumatology 46(8):p 1223-1233, August 2007.

Objective

To systematically review the evidence from randomized clinical trials (RCTs) for the effectiveness of the antioxidant vitamins A, C, E or selenium or their combination in the treatment of arthritis.

Methods

A systematic search of computerized databases from inception to September 2006 for relevant RCTs, application of pre-defined inclusion/exclusion criteria and independent data extraction by two authors. Methodological quality was assessed using the Jadad scale.

Results

The searches identified 20 unique RCTs meeting the inclusion criteria: 11 in inflammatory arthritis and 9 in osteoarthritis (OA). The studies included are generally of poor quality. They fall into three main clusters: selenium for rheumatoid arthritis (n=5); vitamin E for inflammatory arthritis (n=5) and vitamin E for OA (n=7). One RCT suggests superiority of vitamin E over placebo and three RCTs suggest equivalence between vitamin E and diclofenac in the treatment of inflammatory arthritis. In OA, four RCTs compared vitamin E with placebo. Two shorter-term studies were positive and two longer-term studies were negative. Two further RCTs suggest equivalence between vitamin E and diclofenac in the treatment of OA. Findings for selenium, vitamin A and a combination product in inflammatory arthritis and for vitamin A, and a combination product in OA were negative. An isolated positive result for vitamin C in OA is of doubtful clinical significance.

Conclusions

Clinical trials testing the efficacy of vitamin E in the treatment of OA and inflammatory arthritis have been methodologically weak and have produced contradictory findings. There is presently no convincing evidence that selenium, vitamin A, vitamin C or the combination product selenium ACE is effective in the treatment of any type of arthritis.