EDITOR,—Pamela W Ewan's findings with regard to peanut and nut allergy1 agree with my personal experience of the problem: such allergy occurs in otherwise atopic subjects, it is acquired early (possibly in utero in some cases), and after the first adverse reaction sufferers are almost invariably aware of the problem—although in some this is at a subconscious level, and they become averse to all nuts without remembering the reason.

I doubt, however, Ewan's implication that the problem …