The effect of β-carotene on the mortality of male smokers is modified by smoking and by vitamins C and E: evidence against a uniform effect of nutrient.

Compared with the placebo arm, there is highly significant heterogeneity in the BC arm data amongst the three subgroups of A to C, which are categorised by the intake of vitamin C and fruit and vegetables ( P = 0·0004), but no evidence of heterogeneity in the AT and AT + BC arms.

also in 132,142 other papers