Scientists have been suggesting a possible link between lower levels of vitamin D and increase risk of multiple sclerosis and now a new genetic study has found evidence that supports this link.
According to a new study by Brent Richards, from McGill University, Canada, and colleagues a genetic decrease in the natural-log-transformed vitamin D level by one standard deviation was associated with a 2-fold increased risk of multiple sclerosis.
Usually presenting itself in individuals between ages 20 and 40, MS is an incurable autoimmune disease that affects the nerves in the brain and spinal cord. Previous studies have provided observational evidence suggests a possible link between lower vitamin D levels and multiple sclerosis risk, but a causal relationship is difficult to infer because individuals who develop multiple sclerosis in these studies might share another unknown characteristic that increases their risk of multiple sclerosis (this is known as confounding).
To reduce the possibility of confounding, Richards and colleagues used a genetic technique called Mendelian randomization. Researchers were able to establish an association between genetically reduced vitamin D levels and susceptibility to multiple sclerosis among participants in the International Multiple Sclerosis Genetics Consortium study involving 14,498 people with multiple sclerosis and 24,091 healthy controls.
While the Mendelian randomization approach used by the authors largely avoids the possibility of confounding or reverse causation, the reliability of these findings may be limited by some of the assumptions made by the researchers during their analysis.
Despite this the authors conclude that genetically lowered vitamin D levels are strongly associated with increased susceptibility to multiple sclerosis.
“Whether vitamin D sufficiency can delay, or prevent, multiple sclerosis onset merits further investigation in long-term randomized controlled trials”, the authors write.
The authors also note, “ongoing randomized controlled trials are currently assessing vitamin D supplementation for the treatment and prevention of multiple sclerosis … and may therefore provide needed insights into the role of vitamin D supplementation.”
The research article is published in PLOS Medicine.
