Multiple sclerosis (MS) is less likely to develop in persons with high levels of sun exposure and vitamin D, reported Australian researchers in the journal Neurology.1 This finding confirms the results of previous studies that showed MS occurs more frequently at latitudes farther from the equator.
The multicenter, case-control study included 216 persons aged 18 to 59 who had experienced a first demyelinating event; they were matched with 395 controls who had no evidence of CNS demyelination. Self-reported sun exposure, objective measures of skin phenotype and actinic damage, and vitamin D status were assessed.
The researchers found that the risk of a first demyelinating event decreased by 30% for each increase in UV exposure of 1000 kilojoules. They also found that persons with the most actinic damage were 60% less likely to have CNS demyelination than those with the least actinic damage. Study participants with the highest levels of vitamin D also were less likely to have a first demyelinating event than those with lower levels.
This is the first study to look at persons who have just had the first symptoms of MS and have not yet received a diagnosis, according to study author Robyn Lucas, PhD, of Australian National University in Canberra. She cautioned that sun exposure should continue to be limited because of the risk of skin cancer.
1. Lucas RM, Ponsonby AL, Dear K, et al. Sun exposure and vitamin D are independent risk factors for CNS demyelination. Neurology. 2011;76:540-548.