Multiple sclerosis (MS) is more common in parts of the world far from the equator, where the sun wanes during winter. During that seasonal sunshine shortfall, it's harder for the body to make vitamin D when exposed to sunlight.
"If too little of the vitamin is available, the gene may not function properly," making multiple sclerosis more likely, Julian Knight, MBChB, DPhil, says in a news release. Knight works at the Wellcome Trust Centre for Human Genetics at England's University of Oxford.
Knight and colleagues suggest that because vitamin D deficiency is common, taking vitamin D supplements early in life might cut MS risk. But they didn't test that theory, and they're not recommending certain vitamin D doses for MS prevention.
The study appears in PLoS Genetics. "PLoS" is short for "Public Library of Science."