Inverse association between dietary habits with high total antioxidant capacity and prevalence of frailty among elderly Japanese women: a multicenter cross-sectional study.

OBJECTIVE: To examine the association of dietary habits with high total antioxidant capacity (TAC) with frailty among elderly Japanese women.
DESIGN: Cross-sectional multicenter study.
SETTING: Thirty-five of 47 prefectures in Japan. PARTICIPANTS: 2121 grandmothers or acquaintances of dietetic students aged 65 and older. MEASUREMENTS: Dietary TAC and food intakes were calculated using a validated brief-type self-administered diet history questionnaire. The TAC value of each food was assigned using four different assays, ferric reducing ability of plasma (FRAP), oxygen radical absorbance capacity (ORAC), Trolox equivalent antioxidant capacity (TEAC), and total radical-trapping antioxidant parameter (TRAP). Frailty was defined as the presence three or more of the following four components: slowness and weakness (two points), exhaustion, low physical activity, and unintentional weight loss.
RESULTS: The number of subjects with frailty was 486 (23%). Multivariate adjusted ORs (95% CI) for frailty in the highest compared to the lowest quintile were 0.35 (0.24, 0.53) for FRAP, 0.35 (0.23, 0.52) for ORAC, 0.40 (0.27, 0.60) for TEAC, and 0.41 (0.28, 0.62) for TRAP. The intakes of green tea, coffee, vegetables, and fruits which contribute to dietary TAC were also associated with lower odds of frailty (the range of multivariate adjusted OR: 0.47 for vegetables to 0.77 for green tea), although the odds ratios were less marked than those of dietary TAC.
CONCLUSIONS: Dietary habits with high TAC showed a stronger inverse association with frailty in elderly Japanese women than the individual foods examined.