Do you suffer from rheumatoid arthritis (RA)? Can vitamin D help?

Both dietary and supplemental vitamin D reduce the risk of RA, which is an autoimmune disease—a disease in which the body’s immune system attacks its own tissue. In a study of 29,000 women, those who ranked in the top third of vitamin D consumption had one-third less risk of RA.[1] It is likely that a greater vitamin D intake would have produced much better results, since it is virtually impossible to ingest sufficient vitamin D from food and multivitamins.

In studies performed on mice, vitamin D was shown to inhibit the progression of rheumatoid arthritis and minimize or prevent symptoms.[2] The same is true in humans. In subjects diagnosed with a form of the disease known as inflammatory arthritis, the lower the vitamin D levels are, the higher is the disease activity.[3] Vitamin D's anti-inflammatory properties and its ability to reduce the autoimmune response are likely responsible for the improvement in RA.[4]

Investigations also find that RA is more common in winter, consistent with the idea that vitamin D is a major factor in reducing the risk.[5] In a report from researchers in Ireland, it was shown that 70% of patients had low vitamin D levels and that 26% were severely deficient.[6] However, in that report, 21 ng/ml was considered as the deficiency level and 10 as the severe deficiency level. A level of 21 is dangerously deficient. The ideal level of vitamin D is 50-60 ng/ml. Using those numbers, it is likely that all of these patients ranged between deficient and severely deficient.

In our health institute/resort, we observed that guests with arthritis often regained full range of motion in their joints from a week to a month after beginning a program. I assumed that our anti-inflammatory vegetarian nutrition was responsible for the positive results. Now I realize that many of the benefits came from sunlight exposure during outdoor exercise.

RA prevention and relief are two more reasons to obtain regular, non-burning sunlight exposure. Remember that sunscreens can prevent 99% of vitamin D production by the skin.

[1] Merlino, L. et al. Vitamin D intake is inversely associated with rheumatoid arthritis: Results from the Iowa Women’s Health Study. Arthritis & Rheumatism 2004;50:72-77.
[2] Cantorna, M. et al. 1,25-Dihydroxycholecalciferol inhibits the progression of arthritis in murine models of human arthritis. J Nutr1998;128:68-72.
[3] Patel, S. et al. Serum vitamin D metabolite levels may be inversely associated with current disease activity in patients with early inflammatory polyarthritis. Arthritis Rheum 2007;56;2143-49.
[4] Cutolo, M. et al. Vitamin D in rheumatoid arthritis. Autoimmune Rev 2007;7:59-64.
[5] Cutolo, M. et al. Circannual vitamin D serum levels and disease activity in rheumatoid arthritis: Northern versus Southern Europe. Clin Exp Rheumatol 2006;24:702-4.
[6] Haroon, M. Report to European Union League Against Rheumatism , June 13, 2008.