Vitamin D seen as most helpful for males in progressive MS rat model

Vitamin D supplements were associated with less severe disease in a rat model of progressive multiple sclerosis (MS), but male rats tended to experience greater benefits than did females, a study into disease-related sex differences reports.

This higher overall benefit may be due to nerve cells in males being more susceptible to oxidative stress, damage that occurs when the body’s antioxidant defenses cannot counteract the production of free radicals, the researchers noted. Oxidative stress is known to contribute to disease progression in MS, and to be eased with vitamin D.

While more studies are needed to know if these findings hold true for people with MS, understanding how vitamin D supplementation might alter the disease’s course in men and women could help in better tailoring MS treatments.

The study, “Sex Differences under Vitamin D Supplementation in an Animal Model of Progressive Multiple Sclerosis,” was published in the journal Nutrients.

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While MS is about three times more common in women, men who develop the condition often have a more rapid disease progression and worse prognosis. Reasons for this are not clearly understood, but it’s possible that some of these sex differences arise from differences in the levels of sex-related hormones.

Low levels of vitamin D have been extensively linked to an increased likelihood of developing MS. What’s less clear is whether vitamin D levels affect the disease’s course, particularly in progressive forms of MS, and whether the effects of vitamin supplements differ in women and men.

A research team in Austria worked with a rat model of progressive MS, with the animals fed regular food with or without vitamin D supplementation starting at age 3 weeks. Groups of both male and female rats were given the supplement, and the researchers then watched for differences in symptoms and disease features.

Female rats were seen to have a better total antioxidant capacity, meaning antioxidants in their blood were able to scavenge a greater amount of harmful, oxygen-containing free radicals. Damaging free radicals arise as a result of the molecular reactions taking place in cells.

They also showed a greater preservation of the myelin sheath, which is damaged in MS, and fewer activated microglia, immune cells that help to drive the inflammatory attacks that mark the disease. While nerve cell death was more frequent in female than male rats, the disease did not progress as quickly in female animals.

Notably, vitamin D supplementation improved most of these markers in both groups of animals, but male rats experienced a greater reduction in markers of oxidative stress with its use.

Vitamin D also led to a significant reduction in blood levels of neurofilament light chain, a marker of nerve cell damage, in male rats but not in female rats.

Rats of either sex benefited from vitamin D supplementation, but “unexpectedly, male rats had an even higher overall benefit, most likely due to differences in oxidative capacity,” the researchers wrote. “These findings should further be investigated in clinical trials to learn more about these mechanisms in patients.”