The PrevANZ trial investigated whether vitamin D supplements could reduce the likelihood of developing multiple sclerosis (MS) after a first demyelinating event. Over the 48-week study period, vitamin D did not reduce the likelihood of developing MS compared with placebo. The findings do not rule out a possible role for vitamin D earlier in life, before symptoms begin, or among people with vitamin D deficiency.
The Vitamin D MS Prevention Trial – PrevANZ arose from a significant body of evidence linking vitamin D deficiency with MS. Among the evidence is that MS is generally more common in populations living further from the equator, where people may have lower exposure to sunlight and therefore lower vitamin D levels1. Variations in genes involved in the vitamin D metabolism pathway have been implicated in susceptibility to MS2. Lower vitamin D levels have also been associated with higher relapse rates in people with established MS3.
PrevANZ was a world-first Phase IIb randomised, double blind, placebo-controlled clinical trial. The trial included participants who had experienced a diagnosed first episode of neurological symptoms caused by inflammation and damage to myelin. This is known as first demyelinating event (FDE) and may be diagnosed as clinically isolated syndrome (CIS). It can sometimes be an early sign of MS. Symptoms can include blurred vision caused by optic neuritis or limb weakness caused by transverse myelitis.
Participants were randomly assigned to receive one of three oral vitamin D3 doses (1000, 5000 & 10,000 International Units) or placebo for a period of 48 weeks. Neither the participants nor the researchers knew which treatment the participants had been assigned until the trial was completed.
The trial investigated whether vitamin D supplements could delay or prevent further symptoms or MRI changes that met the study criteria for MS. It also assessed the safety of the three vitamin D doses and explored which dose might be most appropriate.
Participants did not need to have a vitamin D deficiency to take part in the trial. Participants’ baseline vitamin D levels were not known during the trial, as they were only analysed after the study had ended.
The trial was conducted at multiple sites across Australia and New Zealand.
Findings of the trial have been published4.
The trial was coordinated and funded by MS Australia, with generous support from state and territory MS organisations, as well as Foundation 5 Million+, the Trish MS Research Foundation and the John T Reid Trust.
The PrevANZ trial found that:
These findings help refine future research questions, including whether vitamin D has a role earlier in life or before symptoms begin, and whether baseline vitamin D levels, dose, timing of supplementation, latitude and sunlight exposure affect MS risk.
The PrevANZ findings should also be considered alongside other recent research, including the D-Lay trial5 in France, which found that people taking high-dose oral vitamin D were less likely to experience a relapse. The trials differed in their designs and participant characteristics, including participant vitamin D levels at the start of the studies and dosage of vitamin D administered. These differences may have contributed to the contrasting findings, but further research is needed to determine which factors were responsible. You can read more about the differences between the two trials here.
These findings do not change current advice about maintaining adequate vitamin D levels for general health. People who are concerned about their vitamin D level or MS risk should seek advice from an appropriate health professional rather than starting high-dose supplements without medical guidance.
Explore the PrevANZ results in more detail through MS Australia’s media release announcing the PrevANZ findings, our news article explaining the findings, or the full scientific paper.
Data and biosamples collected through the PrevANZ trial remain an important resource for researchers seeking to better understand early MS risk, prevention and disease development.
Researchers can apply to access PrevANZ data and biosamples through a controlled access process. The PrevANZ Data Management Committee reviews each request for scientific merit, feasibility and alignment with participant consent, ethics approvals, privacy obligations and applicable data-sharing requirements.
To request access to PrevANZ data or material (biosamples), researchers should complete the material/data request form and email it to research@msaustralia.org.au.
MS Australia would like to thank the many people who contributed data and biosamples to make this research possible.
Professor Helmut Butzkueven (Chair): Monash University and Alfred Hospital, VIC
Professor Anne-Louise Ponsonby: Florey Institute for Neuroscience and Mental Health, VIC
Professor Bruce Taylor: Menzies Institute for Medical Research, TAS
Dr Deborah Mason: University of Otago, Canterbury District Health Board and New Zealand Brain Research Institute, Christchurch, New Zealand
Dr Mark Stein: Royal Melbourne Hospital, VIC
Rachel Fallis: Person living with MS, Lived Experience Expert Panel Member, NSW
Dr Fiona McKay: Deputy Head of Research, MS Australia
Jen Thomson (Secretary): Clinical Platform Coordinator, MS Australia
