The link between exposure to sunlight and multiple sclerosis is now well established. Further, there is very good evidence to support a relationship between vitamin D, the hormone produced by sun exposure, and disease activity in MS. Australian researchers have examined this issue in a randomised, controlled trial.
Unfortunately, the researchers from the Royal Melbourne Hospital in Victoria, chose to use vitamin D2 (ergocalciferol) rather than vitamin D3 (cholecalciferol) in comparing high dose versus low dose supplementation in people with Multiple Sclerosis.
They aimed for a level of around 150nmol/L for the high dose group, and the low dose group received just 1000IU a day. They found no difference in MRI outcomes between groups, but found more people in the high dose group had relapses compared with the low dose.
It is extremely unfortunate that the researchers chose vitamin D2 rather than D3, which has been shown to have beneficial immune effects in people with MS. Whereas D3 supplementation has been shown to reduce mortality in randomised controlled trials, vitamin D2 and other forms of vitamin D have not affected mortality. It is quite likely that vitamin D3 has beneficial effects on human health that are not shared by vitamin D2.
People with MS who are supplementing with vitamin D3 should not modify their supplementation in response to this latest study. For people using vitamin D2, there is good reason to change to vitamin D3 supplementation.