Yoshihiro Miyake1,2,3,4, Keiko Tanaka5,6,7,8, Hitomi Okubo5,6,9,10, Satoshi Sasaki11, Masashi Arakawa12,13. 1. Department of Epidemiology and Public Health, Ehime University Graduate School of Medicine, Toon, Ehime, 791-0295, Japan. miyake.yoshihiro.ls@ehime-u.ac.jp. 2. Integrated Medical and Agricultural School of Public Health, Ehime University, Matsuyama, Ehime, Japan. miyake.yoshihiro.ls@ehime-u.ac.jp. 3. Research Promotion Unit, Translation Research Center, Ehime University Hospital, Toon, Ehime, Japan. miyake.yoshihiro.ls@ehime-u.ac.jp. 4. Center for Data Science, Ehime University, Matsuyama, Ehime, Japan. miyake.yoshihiro.ls@ehime-u.ac.jp. 5. Department of Epidemiology and Public Health, Ehime University Graduate School of Medicine, Toon, Ehime, 791-0295, Japan. 6. Integrated Medical and Agricultural School of Public Health, Ehime University, Matsuyama, Ehime, Japan. 7. Research Promotion Unit, Translation Research Center, Ehime University Hospital, Toon, Ehime, Japan. 8. Center for Data Science, Ehime University, Matsuyama, Ehime, Japan. 9. Japan Environment and Children's Study Programme Office, National Institute for Environmental Studies, Tsukuba, Ibaragi, Japan. 10. Research Fellow of the Japan Society for the Promotion of Science, Chiyoda, Tokyo, Japan. 11. Department of Social and Preventive Epidemiology, Graduate School of Medicine, The University of Tokyo, Bunkyo, Tokyo, Japan. 12. Wellness Research Fields, Faculty of Global and Regional Studies, University of the Ryukyus, Nishihara, Okinawa, Japan. 13. The Department of Cross Cultural Studies, Osaka University of Tourism, Nago, Okinawa, Japan.
Abstract
OBJECTIVE: Tryptophan is an essential amino acid wholly derived from diet. While the majority of tryptophan is degraded through the kynurenine pathway into neuroactive metabolites like quinolinic acid and kynurenic acid, a small proportion of ingested tryptophan is metabolized into the neurotransmitter serotonin. The current cross-sectional study in Japan examined the association between tryptophan intake and depressive symptoms during pregnancy. METHODS: Study subjects were 1744 pregnant women. Dietary intake during the preceding month was assessed using a self-administered diet history questionnaire. Depressive symptoms were defined as a score ≥ 16 on the Center for Epidemiologic Studies Depression Scale. Adjustment was made for age, gestation, region of residence, number of children, family structure, history of depression, family history of depression, smoking, secondhand smoke exposure at home and at work, employment, household income, education, body mass index, and intake of saturated fatty acids, eicosapentaenoic acid plus docosahexaenoic acid, calcium, vitamin D, and isoflavones. RESULTS: The prevalence of depressive symptoms during pregnancy was 19.2%. After adjustment for confounding factors, higher tryptophan intake was independently inversely associated with the prevalence of depressive symptoms during pregnancy: the adjusted prevalence ratios (95% confidence intervals) for depressive symptoms during pregnancy in the first, second, third, and fourth quartiles of tryptophan intake were 1 (reference), 0.99 (0.76-1.28), 0.94 (0.71-1.25), and 0.64 (0.44-0.93), respectively (p for trend = 0.04). CONCLUSIONS: Higher estimated tryptophan intake was cross-sectionally independently associated with a lower prevalence of depressive symptoms during pregnancy in Japanese women.
OBJECTIVE: Tryptophan is an essential amino acid wholly derived from diet. While the majority of tryptophan is degraded through the kynurenine pathway into neuroactive metabolites like quinolinic acid and kynurenic acid, a small proportion of ingested tryptophan is metabolized into the neurotransmitter serotonin. The current cross-sectional study in Japan examined the association between tryptophan intake and depressive symptoms during pregnancy. METHODS: Study subjects were 1744 pregnant women. Dietary intake during the preceding month was assessed using a self-administered diet history questionnaire. Depressive symptoms were defined as a score ≥ 16 on the Center for Epidemiologic Studies Depression Scale. Adjustment was made for age, gestation, region of residence, number of children, family structure, history of depression, family history of depression, smoking, secondhand smoke exposure at home and at work, employment, household income, education, body mass index, and intake of saturated fatty acids, eicosapentaenoic acid plus docosahexaenoic acid, calcium, vitamin D, and isoflavones. RESULTS: The prevalence of depressive symptoms during pregnancy was 19.2%. After adjustment for confounding factors, higher tryptophan intake was independently inversely associated with the prevalence of depressive symptoms during pregnancy: the adjusted prevalence ratios (95% confidence intervals) for depressive symptoms during pregnancy in the first, second, third, and fourth quartiles of tryptophan intake were 1 (reference), 0.99 (0.76-1.28), 0.94 (0.71-1.25), and 0.64 (0.44-0.93), respectively (p for trend = 0.04). CONCLUSIONS: Higher estimated tryptophan intake was cross-sectionally independently associated with a lower prevalence of depressive symptoms during pregnancy in Japanese women.