Prospective Study on the Association Between Adherence to Healthy Lifestyles and Depressive Symptoms Among Japanese Employees: The Furukawa Nutrition and Health Study

BACKGROUND: While a growing body of research suggests a protective role of healthy lifestyle against depression, evidence from prospective studies is scarce. We constructed a healthy lifestyle index (HLI) and examined its prospective association with depressive symptoms in a Japanese working population. METHODS: Participants were 917 employees (19–68 years old) who were free from depressive symptoms at baseline in 2012–2013 and attended the 3-year follow-up survey. The HLI (range: 0–7 points) was constructed by assigning 1 point to each healthy lifestyle factor, namely, (1) normal body mass index (18.5–24.9 kg/m(2)), (2) non-smoking, (3) no or moderate alcohol intake (≤23 g ethanol/day), (4) adequate physical activity (≥7.5 metabolic equivalent-hours/week), (5) high vegetable intake (≥350 g/day), (6) high fruit intake (≥200 g/day), and (7) adequate sleep duration (6–8.9 hours/day), which was categorized into three groups (low: 0–2 points; middle: 3–4 points; and high: 5–7 points). Depressive symptoms were assessed using the Center for Epidemiologic Studies Depression Scale. RESULTS: A total of 155 incident cases (17.0%) of depressive symptoms were identified at the follow-up survey. Compared with the low HLI group, multivariable-adjusted odds ratios of depressive symptoms were 0.74 (95% confidence interval, 0.48–1.15) and 0.55 (95% confidence interval, 0.31–0.99) for the middle and high HLI groups, respectively (P-trend = 0.041). CONCLUSION: The present study suggests the importance of adherence to multiple healthy lifestyle factors in prevention of depressive symptoms.