Could vitamin D help prevent RA?

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Jan 21, 2004

Could vitamin D help prevent RA?

Iowa City, IA - New data from the Iowa Women's Health Study raise the

intriguing possibility that vitamin D may help prevent rheumatoid arthritis

(RA).

Reporting in the January 2004 issue of Arthritis & Rheumatism [1], Dr

Merlino (University of Iowa, Iowa City) and colleagues say: " Although this

finding is hypothesis generating . . . greater intake of vitamin D may be

associated with a lower risk of RA in older women. "

" Greater intake of vitamin D may be associated with a lower risk of RA in

older women. "

The 11-year study of 29 368 women aged 55 to 69 involved detailed questions

about eating habits, use of vitamin pills, and other lifestyle choices.

Overall, 152 women developed rheumatoid arthritis, and a greater intake

(highest vs lowest tertile) of vitamin D was inversely associated with risk

of RA (relative risk 0.67; p=0.05).

Inverse associations were apparent for both dietary and supplemental vitamin

D, but the latter seemed to be a better source of the vitamin than food, the

researchers report.

Merlino et al say while it " is possible that chance alone explains these

results . . . there is a compelling biologic explanation for these

findings. "

They suggest that vitamin D may act as an immunosuppressant. Mouse models of

human RA have shown decreased incidence and severity of disease in mice

treated with active vitamin D, they note. Also, in human rheumatoid joints,

it has been demonstrated that the active form of vitamin D is synthesized in

the synovium and it is thought that it could act to decrease T-cell

responsiveness.

" There is a compelling biologic explanation for these findings. "

" Further studies will be required to corroborate or refute our findings, "

they say. Nevertheless, they add, " Greater intake of vitamin D showed an

inverse association with incident RA in this cohort of elderly women. While

the immunomodulatory effects of vitamin D are not yet fully elucidated, the

results from this study suggest a possible role for vitamin D in reducing

the risk of an immunologic disorder. "

Vitamin D also involved in MS?

Separately, another paper published the January 13, 2004 issue of Neurology

[2] found that women in the Nurses Health Study who took supplements

containing vitamin D were 40% less likely to develop multiple sclerosis than

women who did not. No association was found, however, between vitamin D from

food and MS incidence.

MS and RA are both autoimmune conditions that are more common in northern

climes where sunlight is often scarce, and 1 theory that has been proposed

is that sunlight exposure and high levels of vitamin D may reduce the risk

of these diseases.

Nainggolan

Sources

1. Merlino LA, Curtis J, Mikuls TR, et al. Vitamin D intake is inversely

associated with rheumatoid arthritis: Results from the Iowa Women's Health

Study. Arthritis Rheum 2004 Jan; 50(1):72-7.

2. Munger KL, Zhang SM, O'Reilly E, et al. Vitamin D intake and incidence of

multiple sclerosis. Neurology 2004 Jan 13; 62(1):60-5.