Looking out the window, the day is gray. The sun is blocked by a heavy layer of clouds, it rays barely reaching the ground. In my case, it is overcast because of rainfall. In other places, smog may be the cause. Regardless, it is a poor day for cutaneous synthesis of vitamin D.
According to a systematic review of 195 studies in 44 countries published between 1990 and 2011 (Hilger et al, 2013), my situation is not unique. 88% of the studies had mean serumRead More »