An approach for evaluating lifelong intakes of functional foods in elderly people

Many "functional foods" (FF), common foods with health benefits beyond their nutritive value, have antioxidant properties with the potential to mediate the degenerative changes of aging. A pilot study was conducted among 51 healthy, home-dwelling elderly people aged 70-86 y (51% male) to develop a method for evaluating relationships between lifelong diet and health. A population-based semiquantitative food frequency questionnaire (FFQ) was used to assess the usual diet. A nonquantitative questionnaire (FF-FFQ) was developed to examine current intake patterns of 33 FF, and at ages 65, 45, 25 and 10 y. Visual and memory cues were employed to help respondents remember past intakes, and their reporting confidence was queried. The instrument was self-administered (among 35%), or administered by a dietitian-interviewer in face-to-face (39%) or telephone (25%) interviews. The FFQ was validated by four dietary recalls statistically adjusted for intraindividual and seasonal variability. The FF-FFQ reliability was assessed in a subsample (n = 20). Mean usual FFQ-derived energy intakes were 7941 +/- 2071 kJ (men) and 7033 +/- 1916 kJ (women). Reported current, regular (several times/mo) FF numbered 18 +/- 4 (men) and 20 +/- 4 (women). These means decreased almost linearly with time; at age 10 y, FF reported were 12 +/- 7 (men) and 15 +/- 4 (women). Men differed from women in their memory of food consumption, food choices and FF intakes. Instrument reliability was good, with 73% identical responses. Food-related memory appears to be linked to dietary knowledge, food preparation experience and availability of foods in the past. The FF-FFQ provides novel data on lifetime FF consumption that may help clarify relationships between diet and health, and the role of diet in aging.