Some recent data from a Harvard group involving 25,000+ patients looked at supplementation of Vitamin D at 2000 IU daily and/or Omega-3 Fatty Acids (marine fish oil) at 1 gram daily over a five-year period. The purpose of the study was to look at the development of autoimmune disease such as rheumatoid arthritis, psoriasis, or inflammatory bowel disease such as Crohn's or ulcerative colitis during this period.
In the United States, the incidence of autoimmune conditions has continued to increase. This study showed that over the five-year period, the group taking Vitamin D had a 22% reduction, Omega-3-Fatty Acids a 18% reduction, and the combined group of Vitamin D and Omega-3 had a 31% reduction in the development of an autoimmune condition. The reduced risk was greater in non-obese participants that had a body mass index (measurement of weight divided by height = normal <25) of less than 25 and less beneficial for those with a body mass index above 25.
More reasons to keep vitamin D levels in normal range, watch diet and regular exercise to lower inflammation in our body which has wide ranging effects in a number of disease processes.