The prevalence and characteristics of vitamin supplement users were assessed in 7538 male subjects aged 50-59 from France and 2468 from Northern Ireland. In France, 15% of subjects used vitamin supplements; users were significantly younger, had a lower body mass index, a higher educational level, had more frequently a hard physical job, reported more frequently a personal history of disease and were less frequently retired or inactive than non-users. In Northern Ireland, 21% of subjects were vitamin supplement users; users had a lower body mass index, drank less alcohol, had a higher educational level, were more frequently non-smokers and professionally active, and reported a hard physical job and the practice of leisure sports more frequently than non-users. Finally, vitamin supplement users in Northern Ireland had a lower consumption of alcohol, smoked less, had a lower frequency of personal history of disease and were more frequently on dietary therapy for hypertension or dyslipidaemia than their French counterparts. We conclude that vitamin supplement use is associated with a healthier lifestyle and with dietary measures against hypertension and dyslipidaemia in Northern Ireland. The less favorable lifestyle observed for vitamin supplement users in France awaits further investigation.