Objective: The purpose of the investigation was to assess effects of dietary variety on declines in high-level functional capacity in community dwelling elderly, based on a 5-year longitudinal study (from 1992 to 1997).
Subjects and method: Subjects were a representative sample comprising 235 men (mean age 70.8 years) and 373 women (71.7 years) aged 65 years and above, living in Nangai village in Akita prefecture. Baseline and follow-up surveys were undertaken by the interview method. For assessing dietary variety, we introduced the dietary variety score (DVS), counting the number of 10 food-groups consumed daily from food frequency questionnaires: meat, fish and shellfish, eggs, milk, soybean products, potatoes, green yellow vegetables, fruits, seaweed, and fat and oil. The DVS ranged from 0 to 10 with higher score indicating a higher dietary variety. We also evaluated higher-level functional capacity using the Tokyo Metropolitan Institute of Gerontology Index of Competence (TMIG Index of Competence). Effects of dietary variety on declines in TMIG Index of Competence were analyzed by multiple logistic regression analysis.
Results: The average TMIG Index of Competence score for men and women were 12.1 and 10.8 at baseline, respectively. The mean baseline DVS was 6.3 for men, and 6.2 for women. Relative to the reference groups with DVS in 1-3, the groups with 4-8 and 9-10 scores had lower risks for decrease in TMIG Index of Competence scores over the study period. Relative risks (95% confidence interval) of the groups with a DVS of 4-8 and 9-10 were 0.92 (0.50-1.67) and 0.71 (0.34-1.48) regarding instrumental self maintenance, 0.50 (0.29-0.86) and 0.40 (0.20-0.77) for intellectual activities, and 0.44 (0.26-0.75) and 0.43 (0.20-0.82) for social roles of sub-scales of TMIG Index of Competence, adjusting for age, sex, educational attainment, and the baseline TMIG Index of Competence scores.
Conclusion: Higher dietary variety is associated with a reduced risk of higher-level functional decline in community dwelling elderly.