Vitamin D has lately been projected as a panacea for many diseases including certain cancers. But intake of vitamin D (Vit. D) is unlikely to protect from neurodegenerative diseases including Parkinson’s disease, Alzheimer’s disease, and multiple sclerosis, finds a new study published in the journal Nutritional Neuroscience.
Krystal Iacopetta, Adelaide Centre for Neuroscience Research, University of Adelaide, and colleagues conducted the study to quantitatively assess if neuroprotective benefits from vitamin D in neurodegenerative diseases are dependent on route of administration by comparing the effect of endogenously sourced Vit. D from UV exposure to exogenously derived vitamin D through synthetic supplementation.
The researchers had failed to find solid clinical evidence for Vit. D as a protective neurological agent.
“Our work counters an emerging belief held in some quarters suggesting that higher levels of vitamin D can impact positively on brain health,” says Iacopetta.
The present study was based on a systematic review of over 70 pre-clinical and clinical studies.
“Past studies had found that patients with a neurodegenerative disease tended to have lower levels of Vit. D compared to healthy members of the population,” she says. “This led to the hypothesis that increasing Vit. D levels, either through more UV and sun exposure or by taking Vit. D supplement, could potentially have a positive impact. A widely held community belief is that these supplements could reduce the risk of developing brain-related disorders or limit their progression.”
“The results of our in-depth review and an analysis of all the scientific literature, however, indicates that this is not the case and that there is no convincing evidence supporting vitamin D as a protective agent for the brain,” she says.
Ms. Iacopetta believes that the idea of vitamin D as a neuro-related protector has gained traction based on observational studies as opposed to the evaluation of all the clinical evidence.
“Our analysis of methodologies, sample sizes, and effects on treatment and control groups shows that the link between vitamin D and brain disorders is likely to be associative – as opposed to a direct causal relationship,” she explains.
“We could not establish a clear role for a neuroprotective benefit from vitamin D for any of the diseases we investigated.”
“This outcome is important and is based on an extremely comprehensive review and analysis of current data and relevant scientific publications,” says Mark Hutchinson, Director of the ARC Centre of Excellence for Nanoscale BioPhotonics (CNBP).
“We’ve broken a commonly held belief that Vit. D resulting from sun exposure is good for your brain.” However, Hutchinson notes that there may be evidence that UV light (sun exposure) could impact the brain beneficially, in ways other than that related to levels of vitamin D.
“There are some early studies that suggest that UV exposure could have a positive impact on some neurological disorders such as multiple sclerosis,” he says. “We have presented critical evidence that UV light may impact molecular processes in the brain in a manner that has absolutely nothing to do with vitamin D.”
“Vitamin D, although essential for healthy living, is not going to be the miracle ‘sunshine tablet’ solution for brain-disorders that some were actively hoping for.”
Based on the systematic review, authors concluded that strong recommendations regarding the therapeutic benefits of vitamin D in neurodegenerative disease cannot be made. It is unclear if vitamin D mediates a protective benefit in neurodegenerative disease or whether it is an associative marker of UV exposure, which may contribute to as of yet unidentified neuroprotective factors.
For more information log on to https://doi.org/10.1080/1028415X.2018.1493807