In this 3rd and last in a series of studies published early online in the Journal of Clinical Endocrinology & Metabolism, the authors found an inverse relationship between 25OH vitamin D levels and all-cause mortality. More specifically, they performed a retrospective analysis of a cohort of 182,152 Israelis average 60yo three quarters female followed for 28.5 months. Those in the lowest two quartiles of 25OH vitamin D had a significantly greater all-cause mortality compared to those in the two highest quartiles with a median cut off of 50nmol/L (or 20ng/mL).
Remember that this was an observational study. As such, one can only develop hypotheses, but one cannot demonstrate cause & effect. Still, after taking Monday's, yesterday's & today's recent studies together as a whole along with the others, it's apparent that vitamin D is somehow linked to all-cause mortality, possibly through some association w/calcium. If you think about it, perhaps it's not so surprising that the US Preventive Services Task Force came up w/such controversial draft recommendations. After all, the evidence to support their statement is about as clear as mud.