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Data from the Iowa Women?s Health study, a large-scale research project that began in 1986, show that vitamin D may help protect against rheumatoid arthritis (RA). The findings were published in the January 2004 issue of Arthritis & Rheumatism. For the study, the researchers evaluated 30,000 women, aged 55 to 69, who did not have RA at the beginning of the study.The women were followed for 11 years and were asked about their eating habits, supplement use, smoking history, and body mass index.
The researchers found 152 cases of RA in women during the 11- year follow-up. The results indicated that getting enough vitamin D could lower the risk of RA. "If they took in less than 200 international units (IUs) of vitamin D a day, they had roughly a 33% increased risk for developing [RA], compared with those who received more than 200 IUs daily," said senior investigator Kenneth G. Saag, MD.