Professors Brian Wharton and Ian Booth, from the Institutes of Child Health in London and Birmingham, warned that in people with vitamin B12 deficiency, consumption of folic acid may mask a condition called megaloblastic anaemia - which if not picked up can lead to degeneration of the spinal cord.
Though it is not, in itself, a life-threatening condition, trimethylaminuria leads many sufferers to heavy smoking (in an effort to mask their appalling odour) or, in at least one case, to suicide.