Slashdot has a feature on that
Statisticians have long thought it impossible to tell cause and effect apart using observational data. The problem is to take two sets of measurements that are correlated, say X and Y, and to find out if X caused Y or Y caused X. That’s straightforward with a controlled experiment… But in the last couple of years, statisticians have developed a technique that can tease apart cause and effect from the observational data alone. It is based on the idea that any set of measurements always contain noise. However, the noise in the cause variable can influence the effect but not the other way round. So the noise in the effect dataset is always more complex than the noise in the cause dataset. .. The results suggest that the additive noise model can tease apart cause and effect correctly in up to 80 per cent of the cases (provided there are no confounding factors or selection effects).
and jmlr a more theoretical account
Based on these deliberations we propose an efficient new algorithm that is able to dis- tinguish between cause and effect for a finite sample of discrete variables.
I have probably two candidates here. The first one is by the Cantorna group in October 2013 and provides for the first time a link between between the gut microbiome and oral vitamin D exposure. We all thought that vitamin D has no influence on bacteria as they cannot utilize it. But that doesn’t seem to be true as the composition of the microbiome may change.
Mice that cannot produce 1,25(OH)2D3 [Cyp27b1 (Cyp) knockout (KO)], VDR KO as well as their wild-type littermates were used. Cyp KO and VDR KO mice had more bacteria from the Bacteroidetes and Proteobacteria phyla and fewer bacteria from the Firmicutes and Deferribacteres phyla in the feces compared with wild-type. In particular, there were more beneficial bacteria, including the Lactobacillaceae and Lachnospiraceae families, in feces from Cyp KO and VDR KO mice than in feces from wild-type … Our data demonstrate that vitamin D regulates the gut microbiome and that 1,25(OH)2D3 or VDR deficiency results in dysbiosis, leading to greater susceptibility to injury in the gut.
So while I always thought, oral vitamin D supplementation may have a direct effect on the gut mucosal system, this paper opens a completely new avenue. Continue reading The best vitamin D paper in 2013