Background: Mentally impaired older people are frequently excluded from population surveys for practical reasons; thus their nutritional characteristics are poorly delineated.
Objective: To describe the nutritional characteristics of those who, through mental impairment, were considered to require proxy consent and/or proxy information-givers, within a National Diet and Nutrition Survey (NDNS) of people aged 65 years and over, in the UK.
Design and methods: 2043 participants in the NDNS in mainland Britain during 1994-95 were studied. Proxy consent and/or proxy information was provided by the next-of-kin or a carer for 3% of people living in the community and for 35% of people in institutions. A four-day weighed diet estimate and a single blood sample for nutritional status and clinical chemistry indices were obtained.
Results: Inclusion of people requiring proxy consent and/or information was acceptable to NHS local research ethics committees. These participants differed in certain food choices, nutrient intakes and biochemical status indices, from those not requiring a proxy. They ate more sugary and milky foods. They had lower blood concentrations of haemoglobin, retinol, cholesterol; and higher plasma levels of urea and creatinine.
Conclusions: Older people who require proxy consent or information-givers can be studied in population surveys. They are nutritionally vulnerable and may need special assistance to ensure acceptable nutritional intake and status.