To describe the extent of use of medicines by older people living in Britain, and to explore relationships with vitamin status indices.

The National Diet and Nutrition Survey of people aged 65 years and over collected data from a British sample during 1994–95. The present study has made novel use of it, to relate medicine use with biochemical indices of vitamin status.

Eighty postcode areas, selected randomly from mainland Britain.

1506 people, 65 years and over gave information about use of medication, and a 4-day weighed food record. Three-quarters gave blood for status indices.

78% of those living in the community and 93% of those in institutions were using medication. Certain vitamin status indices: plasma retinol, erythrocyte folate and riboflavin, paradoxically suggested better status in users than in non-users of antihypertensive, gastrointestinal, central nervous system, corticosteroid or diabetic drugs. There was evidence of a link with renal insufficiency, especially for plasma retinol, but neither this nor increased nutrient intake, acute phase effects or haemoconcentration could explain the paradoxical associations.

Caution is needed in interpreting certain vitamin status indices, especially in older people who are extensively using medicines. New vitamin indices are needed, to avoid confounding interferences.