vitamin B12

It's a given that the vitamins are necessary for life; but over the years there have been efforts to demonstrate that they also hold almost magical properties with respect to various diseases and conditions — think Linus Pauling with his theories on vitamin C and cancer or the attempt to show that beta-carotene could ameliorate the effects of smoking on lung cancer (neither of which stood up to scrutiny). And more recently, vitamin D has been seen as a candidate for miracle ingredient — this hasn't panned out either, as we explained here. Now we've become aware that several B vitamins are being tested to see if they can prevent the effects of air pollution on the cardiovascular system.

The most recent...