Low blood levels of Vitamin D is highly correlated with just about every disease known to mankind.
Yet, studies repeatedly have shown that Vitamin D supplementation has next to no benefit in curing those diseases.
So either there's a jointly correlated third factor like sun exposure or low Vitamin D levels are CAUSED by those diseases and in general just an indicator of overall poor health.
Source?
Every article/discussion that shows up here suggests the jury is still out in this as well.
- High incidence of MS in northern hemisphere compared to low incidence near the equator. http://www.bandolier.org.uk/booth/neurol/MSgeog.html
- Better outcome for skin cancer patients if diagnosed going into summer vs winter. https://onlinelibrary.wiley.com/doi/abs/10.1111/dth.13625
There's a decent article on the subject on nih.gov here: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2290997/
And another by Harvard here: https://www.health.harvard.edu/diseases-and-conditions/benef...
The reduction in mortality remains after controlling for level of exercise. Also, using sunbeds and sunbathing while on holiday is associated with reduced mortality, at least in this large study in Sweden:
Vitamin D 100% cures a vitamin D deficiency. And Vitamin D deficiency 100% causes disease.
This study was only looking at how vitamin D supplementation affected a large swath of people, both those deficiency and those replete. So why is everyone surprised the results ar inconclusive?