Vitamin D, further evidence of role in autoimmune diseases
arthritis, according to a new study that investigates the link
between the vitamin and reduced risk of the disease in
postmenopausal women.
Rheumatoid arthritis is thought to be caused by a cellular immune response directed at an unknown antigen. Medical care costs for rhuematoid arthritis exceed $6000 per year per patient, according to the World Health Organisation.
US-based researchers analysed data from a prospective cohort study of 29,368 women, aged 55-69 years, without a history of the disease at study baseline. A food frequency questionnaire recorded both dietary and supplemental vitamin D use.
Following up 11 years later, the team found that high intake of vitamin D was inversely associated with risk of rheumatoid arthritis. Those consuming at at least 400 IU of supplemental vitamin D each day saw a 34 per cent reduction in risk of the disease. The findings for dietary vitamin D were not statistically significant.
And no individual food item high in vitamin D content or calcium was strongly associated with reduced risk of the disease. However, there was a trend toward a lower rheumatoid arthritis risk with greater intake of milk products, report the scientists in this month's issue of Arthritis & Rheumatism (vol 50, issue 1, pp72 -77).
They add that further research is needed to confirm that increasing the intake of vitamin D may be associated with a lower risk of rhuematoid arthritis in older women.
Vitamin D is known to play a vital role in metabolising bone but its effects on the immune system have not been so well defined. A recent study found an association between a mother's intake of vitamin D during pregnancy and reduced risk of type 1 diabetes, caused by an autoimmune reaction, in her offspring.
