It is known that if you are born above 35° latitude at approximately Atlanta, Georgia, and live at this latitude for the first ten years of your life that you have a 100% increase risk of developing multiple sclerosis. Recent studies have suggested that women and men who increase their vitamin D intake above 400 IU of vitamin D a day reduces risk of developing multiple sclerosis by approximately 40%.
Munger KL, Zhang SM, O’Reilly E, Hernan MA, Olek MJ, Willett WC, Ascherio A. Vitamin D intake and incidence of multiple sclerosis. Neurology 2004; 62(1):60-5.
Munger KL, Levin LI, Hollis, BW, Howard NS, Ascheino A. Serum 25-hydroxyvitamin D levels and risk of multiple sclerosis. JAMA 2006; 296:2832-2838.
Ponsonby A-L, McMichael A, and van der Mei I. Ultraviolet radiation and autoimmune disease: insights from epidemiological research. Toxocology 2002;181-182:71-78.