(HealthDay News) — Vitamin D supplementation, with or without omega-3 fatty acid supplementation, is associated with a significant reduction in the incidence of autoimmune disease, according to a study published online Jan. 26 in The BMJ.
Jill Hahn, ScD, from the Harvard T.H. Chan School of Public Health in Boston, and colleagues randomly assigned 12,786 men aged 50 years and older and 13,085 women aged 55 years and older to vitamin D (2,000 IU/day) or matched placebo and omega-3 fatty acids (1,000 mg/day) or matched placebo. All incident autoimmune diseases were self-reported from baseline to a median of 5.3 years.
The researchers found that for the vitamin D arm, 123 and 155 participants in the treatment and placebo groups, respectively, had confirmed autoimmune disease (hazard ratio, 0.78; 95% CI, 0.61-0.99; P = .05). In the omega-3 fatty acids arm, a confirmed autoimmune disease was reported by 130 and 148 participants in the treatment and placebo groups, respectively (0.85; 0.67-1.08; P = .19).
Confirmed autoimmune disease was reported in 63 participants who received vitamin D and omega-3 fatty acids (0.69; 0.49-0.96), 60 who received only vitamin D (0.68; 0.48-0.94), and 67 who received only omega-3 fatty acids (0.74; 0.54-1.03) compared with 88 patients in the reference arm who received both placebos.
“Autoimmune diseases are common in older adults and negatively affect health and life expectancy,” Hahn said in a statement. “Until now, we have had no proven way of preventing them, and now, for the first time, we do.”