Does vitamin D affect risk of developing autoimmune disease?: a systematic review

Area of Science:

• Immunology
• Endocrinology
• Epidemiology

Background:

• Vitamin D plays a role in regulating both innate and acquired immune responses.
• Polymorphisms in the vitamin D receptor gene have been linked to increased risk of various autoimmune diseases.
• Animal studies suggest vitamin D supplementation can prevent or delay the onset of autoimmune conditions.

Purpose of the Study:

• To evaluate the epidemiologic evidence connecting vitamin D with the risk of developing human autoimmune diseases.
• To systematically review existing research on vitamin D levels, supplementation, and autoimmune disease pathogenesis.

Main Methods:

• A comprehensive literature search of PubMed (English, inception-April 2010) was conducted using keywords: "vitamin D," "autoimmune," and specific autoimmune disease names.
• In vitro, animal, and genetic association studies were summarized.
• Epidemiologic studies were categorized by design and disease, focusing on cross-sectional, interventional, and prospective data.

Main Results:

• Seventy-six studies found associations between vitamin D levels and autoimmune disease, particularly in patients with active disease.
• Nineteen observational or interventional studies explored vitamin D supplementation as a therapy for autoimmune diseases, yielding varied results.
• Prospective human studies on vitamin D levels or intake and autoimmune disease risk presented conflicting findings; no interventional trials addressed vitamin D's effect on human autoimmune disease risk.

Conclusions:

• Cross-sectional data suggest a potential role for vitamin D in preventing autoimmune diseases.
• Robust prospective interventional evidence in humans is currently lacking to confirm vitamin D's impact on autoimmune disease risk.