High tomato and tomato product consumption is protective against the decline in handgrip strength among Japanese adults: The oroshisho study

Background: There is scarce epidemiological evidence regarding the relationships of the consumption of different types of vegetables or fruits with change in skeletal muscle strength. We prospectively examined the relationships among Japanese adults, using handgrip strength to assess skeletal muscle strength. Methods: A 3-year study was carried out with 259 Japanese adults who were 22–68 years of age. The frequency of consumption of different types of vegetables or fruits were obtained using a validated self-administered dietary history questionnaire. Handgrip strength was measured with a handheld digital Smedley dynamometer. Results: After adjustment for confounding factors, the mean change in handgrip strength in participants stratified according to the level of tomato and tomato product consumption at baseline were −3.2 (95% confidence interval [CI], −4.0 to −2.3) for <1 time=week, −2.7 (95% CI, −3.6 to −1.8) for 1 time=week, −1.6 (95% CI, −2.5 to −0.8) for 2–3 times=week, and −1.7 (95% CI, −2.8 to −0.7) for ≥4 times=week, (P for trend = 0.022). However, the significant relationships of consumption of other types of vegetables and different types of fruits with change in handgrip strength were not observed. Conclusion: Higher consumption of tomato and tomato product at baseline was significantly associated with reduced decline in handgrip strength among Japanese adults over a 3-year follow-up period. This study suggests that consumption of tomato and tomato product could be protective against the decline in skeletal muscle strength associated with aging.