Rheumatoid Arthritis and Osteoarthritis
Recent studies have revealed that women who ingest more than 400 IU of vitamin D a day reduce their risk of developing rheumatoid arthritis by as much as 42%.
Vitamin D deficiency has been associated with an increased risk of developing osteoarthritis.
Merlino LA, Curtis J, Mikuls TR, Cerhan JR, Criswell LA, and Saag KG. Vitamin D intake is inversely associated with rheumatoid arthritis. Arthritis & Rheumatism 2004; 50(1):72-77.