A study showed a positive effect of daily multivitamin use on cancer incidence in men but not women because women in the treatment group had identical or even higher concentrations of certain minerals compared to the placebo group, indicating inadequate dosing or lack of compliance in women.

“in one of the studies there was shown a a positive effect was shown on daily multivitamin use on cancer incidents in men but not in women now when I closely examined the data what I found was that when you look at the vitamin and mineral concentrations in plasma in the treatment group in women compared to the placeo group in women their concentrations were identical and in fact in some cases the placeo group had higher concentrations of a certain mineral so this explains why there was no effect of multivitamin use in women but there was in men”