Ageing is associated with numerous anatomical and physiological changes which can adversely affect both physical function and muscle strength, thus contributing to an increased risk of falls, fractures and disability. A growing body of observational evidence suggests that fruit and vegetable (FV) intake, which is often low in older people, and/or nutrients associated with a diet high in FV may protect against age-related decline in physical function and muscle strength( Reference Cesari, Pahor and Bartali 1 – Reference Robinson, Jameson and Batelaan 5 ). However, this hypothesis has not yet been fully tested in intervention studies involving free-living older adults. The aim of the present study was to examine the effect of increased FV consumption on measures of muscle strength and physical function among healthy, free-living older adults.
A randomized controlled intervention study was undertaken. Eighty-three participants, aged 65 years and older and habitually consuming ⩽2 portions of FV/day, were randomised to continue their normal diet (⩽2 portions/day), or to consume ≥5 portions of FV/day for 16 weeks. FV were delivered to all participants each week, free of charge. Compliance was monitored at baseline, 6 weeks, 12 weeks and 16 weeks by diet history and by measuring biomarkers of micronutrient status. Grip strength was measured by a hand-held dynamometer, while lower-extremity physical function was assessed by performance-based measures. Ethical approval for the study was obtained from the Office for Research Ethics Committees Northern Ireland (ORECNI).
Eighty-two participants completed the intervention. At week 16, the 5 portions/day group showed greater change in daily FV consumption compared to the 2 portions/day group (P<0.001). The change in vitamin C, lutein, zeaxanthin, β-cryptoxanthin and lycopene over the 16 weeks also differed significantly between groups, being higher in the 5/day group. No significant differences were evident in change in physical function between the two groups. However, there was a trend towards a greater change in grip strength in the 5 portions/day compared to the 2 portions/day group (P=0.06).
aChange calculated as wk 16–baseline. bSignificant difference between groups at baseline (P<0.001, independent samples t-test). cScores range from 1–4 where 1 represents poor balance, 4 represents best balance. dValues are number of participants (all such values). eSPPB=Short physical performance battery score=sum of standing balance score+walk speed score+chair stand score. SPPB score ranges from 3–12 .
Increased FV consumption had no effect on physical function. FV may enhance muscle strength in older adults however this observation needs to be confirmed in further intervention studies.
