Vitamin/mineral supplement use among general practice patients in the United Kingdom.

Many patients take vitamin/mineral supplements, sometimes in doses which may cause toxicity. A survey of 186 patients in one general practice showed that 44% consumed supplements; almost half of these took them daily, and over half had taken them for longer than a year. Younger patients were more likely to take vitamins than older ones. Multivitamins were the most frequently used supplement, followed by iron and vitamin C. Major reasons patients cited for supplement use were to ensure good nutrition, to prevent illness, and for tiredness/fatigue. Patients were most influenced in their decision to take vitamins by family and friends rather than by doctors. General practitioners may find it valuable to include questions about vitamin/mineral supplement use in the medical history.