The preliminary study, which found supplements ineffective at reducing brain lesions, paves the way for a larger trial seeking definitive answers on whether high doses are beneficial, harmful or neutral.
The findings appear today in the journal Neurology.
The trial involved 23 participants who had clinically active relapsing remitting multiple sclerosis (MS) – the most common type. Researchers gave patients low dose vitamin D2 (1000 international units) daily, while 11 people also received a high dose supplement to mimic blood levels found in people from sunny climates. They also underwent MRI scans at athe start of the study and again at four, five and six months.
The scans revealed no significant difference in the volume or number of new brain abnormalities during the six month trial – 14 lesions in high dose group compared with 11 in the low dose group, meaning there was no difference in brain inflammation or nervous system scarring regardless of dose.
“We did not find added benefit from high-dose vitamin D over and above ongoing low-dose supplementation but these results need to be confirmed with larger studies,” says study lead author, Dr Mark Stein from the Royal Melbourne Hospital and Walter and Eliza Hall Institute of Medical Research.
“Previously there was no data comparing doses so findings provide a solid foundation for a larger study to confirm one way or another.”
“We are not saying vitamin D doesn’t work, but if it does, there appears no benefit of high over low. Although we found no evidence of benefit, it doesn’t mean there isn’t a benefit.”
The researchers downplay the finding that some of the high dose participants had relapses (there were no relapses in the low dose group), or that high dose patients were more likely to score poorly on a disability scale at the study’s end.
“I wouldn’t say high dose is harmful because these findings were of borderline statistical significance as there were only 23 participants, but high dose was unlikely to have favourable effects,” says Stein.
MORE RESEARCH NEEDED
According to Stein, the participants had MS for an average six years, adding that it may be possible that earlier high dose supplementation may lead to different results.
Research shows there is more MS in places with less sunshine and a strong association between vitamin D levels and chances of getting MS and relapse.
“There is tremendous interest about vitamin D among patients and the medical community because it is a cheap, oral treatment whereas MS drugs are expensive injections but it’s best to stick to proven therapies and wait for hard evidence on vitamin D,” he says.
The group is hoping to fund a larger study in Australia and New Zealand expected to start soon.
An MS Australia spokesperson said: “We are excited about the possible link between vitamin D and multiple sclerosis. We are encouraged by the ongoing inquiry into this area and eagerly await results of further studies.”
The study was funded by The Myer Foundation.