The Ebers effect: Unraveling the MS and vitamin D connection

Canadian professor receives the 2013 John Dystel prize for research on MS and vitamin D.

by Elinor Nauen

Doctors and medical researchers are often compared to detectives, tracking down clues—not to solve a crime but to make a diagnosis and suggest treatment. Professor George C. Ebers, MD, of the University of Oxford in London, is one such detective, investigating the case of multiple sclerosis.

He has made extensive contributions to understanding the disease, shedding new light on factors such as genes that contribute to susceptibility to MS, as well as other factors that influence who eventually gets MS.

For this work, Dr. Ebers was awarded this year’s John Dystel Prize for MS Research. The $15,000 prize, given jointly by the National MS Society and the American Academy of Neurology, has been awarded since 1995 in honor of John Dystel, a young lawyer—and one-time patient of Dr. Ebers—whose career and life were cut short by progressive MS. The prize is given to a scientist who has made significant, wide-ranging and exciting contributions to the understanding, treatment or prevention of MS.

Science sleuth
Dr. Ebers followed clues to tease out the link between sunlight and MS. “In 1987, in The New England Journal of Medicine, I said the geography of MS had to be determined by climate or diet or both,” he says. “Vitamin D was attractive because it was sourced via both climate and diet.” His continuing investigation throughout the subsequent decades has clarified the connection.

The biggest clue to the vitamin D and MS correlation, Dr. Ebers says, “was that the risk of MS was determined very strongly by where you live. We knew that if English, Welsh or Irish people moved to South Africa or Australia, their risk for MS would go down 80 percent. But studies of families, adoptees, stepchildren and half-siblings raised together and apart all exonerated the effect of family and household conditions. Risk appeared to be determined by the place, acting at a broad population level, in much the same way as a local virus.”

Dr. Ebers sifted through the evidence. “For 3 million years humans were naked on the plains of Africa, and plenty of vitamin D was made in the skin from sunlight.” As humans migrated northward, they became deficient in vitamin D, which led to evolutionary changes toward lighter skin. “The frequency of MS increases with distance from the equator,” he continues, “suggesting that one risk factor may be vitamin D, which is only synthesized in the body when sunlight is of sufficient strength.”

Take Scotland, for one example. Unlike countries with year-round sunshine—and fewer cases of MS—Scotland has too little sunlight for people to make adequate amounts of vitamin D. The typical Scot shows evidence of vitamin D deficiency having influenced his or her appearance: The light skin, reddish hair and freckling are all genetic adaptations aimed at maximizing vitamin D production in the skin. The Scots’ diet used to contain higher levels of vitamin D, but in the 50 years since their diet changed, MS levels in Scotland have tripled. There are some exceptions to this latitude effect, but they seem to still correlate with low vitamin D levels.