The one deficiency that isn't making the headlines

And no, it's not protein or magnesium!

Judging by the urgency and doomsday-esque nature of social media ‘warnings’ about the precipitous decline of the nutrient content of our fresh fruit and vegetables, it’s a miracle we don’t see more scurvy and night blindness in London’s GP clinics. On the other hand, judging by the phenomenal success of protein supplements, we might also all have been a…