Hitomi Suga1, Keiko Asakura2, Satomi Kobayashi3, Masanori Nojima4, Satoshi Sasaki3. 1. Department of Social and Preventive Epidemiology, School of Public Health, The University of Tokyo, Tokyo, Japan. Electronic address: hitomis-tky@umin.ac.jp. 2. Department of Environmental and Occupational Health, School of Medicine, Toho University, Tokyo, Japan. 3. Department of Social and Preventive Epidemiology, School of Public Health, The University of Tokyo, Tokyo, Japan. 4. Division of Advanced Medicine Promotion, The Advanced Clinical Research Center, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan.
Abstract
BACKGROUND: The intake of tryptophan, the precursor of serotonin, is assumed to affect serotonin availability and depression onset. Nevertheless, a definitive relationship between dietary tryptophan intake and depressive symptoms has not been established. We examined the association between tryptophan intake and depressive symptoms screened in a group of 4272 first-year female dietetic students and 3651 their mothers. METHODS: Dietary tryptophan intake during the preceding month was assessed with a validated, self-administered diet history questionnaire. Depressive symptoms were assessed with the Center for Epidemiologic Studies Depression Scale (CES-D) using two cutoff scores: CES-D score ≥ 16 and CES-D score ≥ 19 (the optimal cutoff score for Japanese people). The multivariate adjusted prevalence ratio (PR) and 95% confidence interval (CI) for depressive symptoms were calculated using Poisson regression analysis. RESULTS: The prevalence of depressive symptoms (CES-D score ≥ 16) was 50.0% for young women and 26.5% for middle-aged women. The adjusted PR (95% CI) for depressive symptoms in the highest versus lowest quintile of tryptophan intake was 0.84 (0.75, 0.93) in young women (P for trend < 0.0001) and 0.83 (0.64, 1.01) in middle-aged women (P for trend < 0.0001). These associations were stable even when depressive symptoms were defined as a CES-D score ≥ 19. LIMITATIONS: This is a cross-sectional study. Depressive symptoms were assessed using a self-reported questionnaire. CONCLUSIONS: This cross-sectional study showed that a higher tryptophan intake was independently associated with a lower prevalence of depressive symptoms in young Japanese women.
BACKGROUND: The intake of tryptophan, the precursor of serotonin, is assumed to affect serotonin availability and depression onset. Nevertheless, a definitive relationship between dietary tryptophan intake and depressive symptoms has not been established. We examined the association between tryptophan intake and depressive symptoms screened in a group of 4272 first-year female dietetic students and 3651 their mothers. METHODS: Dietary tryptophan intake during the preceding month was assessed with a validated, self-administered diet history questionnaire. Depressive symptoms were assessed with the Center for Epidemiologic Studies Depression Scale (CES-D) using two cutoff scores: CES-D score ≥ 16 and CES-D score ≥ 19 (the optimal cutoff score for Japanese people). The multivariate adjusted prevalence ratio (PR) and 95% confidence interval (CI) for depressive symptoms were calculated using Poisson regression analysis. RESULTS: The prevalence of depressive symptoms (CES-D score ≥ 16) was 50.0% for young women and 26.5% for middle-aged women. The adjusted PR (95% CI) for depressive symptoms in the highest versus lowest quintile of tryptophan intake was 0.84 (0.75, 0.93) in young women (P for trend < 0.0001) and 0.83 (0.64, 1.01) in middle-aged women (P for trend < 0.0001). These associations were stable even when depressive symptoms were defined as a CES-D score ≥ 19. LIMITATIONS: This is a cross-sectional study. Depressive symptoms were assessed using a self-reported questionnaire. CONCLUSIONS: This cross-sectional study showed that a higher tryptophan intake was independently associated with a lower prevalence of depressive symptoms in young Japanese women.