The turn of the year may not only indicate many new chances but also allow a higher standpoint. IMHO the best paper in the vitamin field was published by Rousseau Gama in the BMJ 2012;345 :e5706.
We measured serum C reactive protein and 25-hydroxyvitamin D concentrations before and two days after elective knee or hip surgery in 30 patients. After surgery the mean serum concentration of C reactive protein increased (5.0 (SD 5.5) v 116.0 (81.2) mg/L; P <0.0001), whereas serum 25-hydroxyvitamin D decreased (56.2 (30.3) v 46.0 (27.6) nmol/L; P <0.0006).
The reasons are not fully clear but the results are consistent with two other studies reporting a fall in serum 25-hydroxyvitamin D concentration during a systemic inflammatory response. So, it looks like 1 simple study will make 1000 other studies useless. That seems to be the beauty of science… although I do not understand how that related to a serum half-life of two weeks?
So far I argued that vitamin D is always a lifestyle proxy e.g. pubmed/22698792) but there maybe also biological reasons.
BTW I would also have a candidate for the worst vitamin D paper, just in case, ….