Kei Hamazaki

• Professor at Gunma University

Background Paternal childcare is reported to benefit maternal mental health, but specific childcare behaviors have not been comprehensively determined. This study sought to identify paternal childcare behaviors associated with maternal mental health by adjusting for other covariates associated with maternal mental health and examining childcare beh...

We investigated the relationship between maternal smoking history and congenital anomalies in children. Drawing on data from the Japan Environment and Children’s Study collected between January 2011 and March 2014, the smoking habits of pregnant women were categorized as “never smoked,” “quit before pregnancy, “quit after pregnancy,” and “full smok...

House dust, well known for causing allergy, contains chemicals that are harmful to fetal neurodevelopment. However, whether countermeasures for house dust allergy, such as frequent use of vacuum cleaners, frequent airing of futons, and the usage of anti-mite covers during pregnancy, are related to subsequent reduced risk of infant developmental del...

This research aimed to examine the efficacy of the early initiation of breastfeeding within 1 h of birth, early skin-to-skin contact, and rooming-in for the continuation of exclusive breastfeeding until 6 months postpartum. The research used data from the Japan Environment and Children’s Study (JECS), a nationwide government-funded birth cohort stu...

The beneficial effects of n-3 polyunsaturated fatty acids (PUFAs) such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on depression are not definitively known. In a previous population-based prospective cohort study, we found a reverse J-shaped association of intake of fish and docosapentaenoic acid (DPA), the intermediate metabolite...

Background : Breastfeeding is increasingly being promoted worldwide. Although several studies have examined breastfeeding and postpartum depression, contradictory results concerning their relationship have been found. This study investigated the influence of the feeding patterns of 1- to 6-month-old infants on maternal postpartum depression, as wel...

Background: Posttraumatic stress disorder (PTSD) symptoms are known to occur after acute coronary syndrome (ACS). Peritraumatic distress has been indicated as a risk factor for PTSD and can be measured by the Peritraumatic Distress Inventory (PDI). However, no studies have yet measured peritraumatic distress after ACS using the PDI to predict PTSD....

〈Background〉 We reported on the characteristics of green tea extract (GTE)-induced hepatotoxicity in rats. Using this model, we explored the inhibitory effects of n-9 PUFA, mead acid (MA), by dietary supplementation. 〈Methods〉 7-week-old male Sprague-Dawley rats received a single intraperitoneal injection of 200 mg/kg GTE, serum and liver were coll...

Autism spectrum disorder is a neurodevelopmental disorder characterized by difficulties in social communication and interaction, as well as repetitive and characteristic patterns of behavior. Although the pathogenesis of autism spectrum disorder is unknown, being overweight or obesity during infancy and low weight at birth are known as risks, sugge...

In the present study, the therapeutic effects of dietary supplemental mead acid (MA), an n-9 polyunsaturated fatty acid, was tested in two different acute liver injury rat models. Six-week old Sprague Dawley rats were given basal diet with and without 4.8% MA. One-week later control rats remained on their basal and 4.8% MA diets while treated rats...

The increasing prevalence of obesity and its effects on our society warrant intensifying basic animal research for understanding why habitual intake of highly palatable foods has increased due to recent global environmental changes. Here, we report that pregnant mice that consume a diet high in omega-6 (n-6) polyunsaturated fatty acids (PUFAs) and...

Background: Although emerging evidence indicates a relation between maternal intake of fish and improved child neurodevelopment, the results are inconsistent. Objectives: This study investigated whether dietary consumption of fish during pregnancy is associated with offspring neurodevelopment at age 6 mo and 1 y. As exploratory research, we also...

Background: Previous studies revealed positive, negative, and no influence of social capital on the health outcomes of pregnant women. It was considered that such differences were caused by the disparities of outcome measures and sample sizes between studies. Our chief aim was to verify the positive influence of social capital on the health condit...

Background There is growing evidence of an association between cadmium (Cd) and unfavorable birth outcomes. The effect of Cd exposure on anthropometric measures at birth or small for gestational age (SGA) infants in a large, nationwide Japanese cohort remains to be clarified. Objectives To analyze the association between maternal blood Cd levels a...

Background Limited research exists on how dietary pattern (DP) influences pregnant women’s health-related quality of life (HRQOL). This study aimed to identify DPs in a cohort of 92,448 pregnant Japanese women using fixed data from the Japan Environment and Children’s Study (JECS) to investigate the associations of DP with HRQOL. Methods During th...

The Edinburgh Postnatal Depression Scale (EPDS) is frequently used to screen for postpartum depression. However, its factor structure exhibits noticeable inconsistencies between studies. We examined the EPDS at two postpartum time points using a large dataset from outside Western countries. Participants were 91,063 mothers in an ongoing birth cohor...

Fetal exposure to particulate matter (PM) is associated with infant developmental delay likely via neuroinflammation and prefrontal cortex lesions; however, whether air-purifier usage, which can reduce indoor PM levels, is related to infant developmental delay remains unknown. We therefore examined the prospective relationship between air-purifier...

Evidence is mixed on the associations between physical activity during pregnancy and perinatal depression, and it is limited for different physical activity intensities. Data for 92,743 pregnant women from the Japan Environment and Children’s Study were analyzed in this study. Psychological distress during pregnancy was assessed as moderate or seve...

A mode of action of acetaminophen （APAP）-induced renal toxicity is supposedly via N-acetyl-p-benzoquinone imine. In this renal toxicity model we explored the inhibitory effects of mead acid （MA）, which is an n-9 PUFA of dietary supplementation. Seven week-old male SD rats received a single intraperitoneal injection of 500 mg/kg APAP and serum and k...

Introduction: Omega-3 polyunsaturated fatty acids (n-3 PUFAs) are recommended as an integrative treatment for major depressive disorder (MDD). In 2019, the International Society for Nutritional Psychiatry Research (ISNPR) developed the first practice guidelines for n-3 PUFA treatment of MDD. To strengthen these guidelines and enhance their clinica...

Background: Lower socioeconomic status is often thought to be associated with an elevated risk of postpartum depression; however, this relationship exhibits noticeable heterogeneity between studies. The present study examined this relationship in Japan. Methods: Data were obtained from 90,194 mothers in an ongoing birth cohort of the Japan Envir...

Objective Tobacco smoke contains over 7,000 chemical compounds, tobacco smoking is a possible risk factor of congenital anomalies (CAs). Therefore, we investigated the relationship between maternal smoking during pregnancy and CAs in children. Drawing data from the Japan Environment and Children’s Study (JECS), gathered between January 2011 and Mar...

Background The association between particulate matter (PM), including desert dust, and allergic symptoms has not been well studied. We examined whether PM exacerbated nose/eye/respiratory symptoms in infants, with a focus on the desert dust element, and assessed possible countermeasures. Methods We conducted a panel study of 1492 infants from Octo...

Background: Although there has been an increase in reports regarding the association between perinatal risk factors and mother-infant bonding, the results have been inconsistent. Methods: This is an ongoing cohort designed study to measure the effect of environmental factors on children's health with the use of data from the Japan Environment an...

Objectives We examined the factors related to lost-to-follow-up of a birth cohort study during the first year after delivery. Design Longitudinal cohort study. Setting Questionnaires were provided by mail. Mothers answered the questionnaires about the children twice: at 6 months and 1 year. Participants Of 103 062 pregnancies who consented to pa...

Background The important role played by intestinal bacterial flora in human health has recently attracted public attention worldwide. Although yogurt is thought to help in preventing the onset of gastroenteritis, this property has rarely been examined in epidemiological studies. Method This study analyzed data obtained by the Japan Environment and...

Background Evidence indicates that human circadian rhythm is affected by the intestinal microbiota, and establishment of the circadian rhythm begins during fetal development. However, the relationship between maternal fermented food intake and infant sleep duration has not been previously investigated. In this study, we examined whether dietary con...

Background Pregnant women require increased levels of n-3 polyunsaturated fatty acids (PUFAs) due to the demands of the growing fetus. Although some evidence indicates that maternal intake of fish and n-3 PUFAs is associated with reduced risk of postpartum depression, the results are inconsistent. Methods We investigated whether dietary consumptio...

Omega-3 polyunsaturated fatty acids (PUFAs) are essential nutrients demonstrated to have health benefits, such as decreasing the risk of coronary heart disease, improving parameters associated with metabolic syndrome, and decreasing anxiety symptoms and depression risk. Previous intervention studies indicated the association between blood or tissue...

Major depressive disorder (MDD) is a complex mental illness with unmet therapeutic needs. The antidepressant effects of ω-3 polyunsaturated fatty acids (n-3 PUFAs) have been widely reported. The subcommittee of the International Society for Nutritional Psychiatry Research organized an expert panel and conducted a literature review and a Delphi proc...

Background Postpartum depression is a major mental health issue. It not only adversely affects the mother's quality of life, but also mother-infant bonding. However, the relationship between postpartum depression (at multiple points after childbirth) and mother-infant bonding failure one year after birth is not well understood. This study investiga...

Cardiovascular disease is a known risk factor for the development of psychiatric disorder and about 20% of patients with acute coronary syndrome (ACS) develop depression. Our previous prospective study showed that serum linoleic acid (LA) level at baseline (admission) is a risk factor for the development of psychiatric disorder 3 months later. Howe...

Objectives Non-response to questionnaires in a longitudinal study reduces the effective sample size and introduces bias. We identified the characteristics of non-respondent pregnant women, and compared them with respondents in the Japan Environment and Children’s Study (JECS) during the gestational period. Design This was a questionnaire-based, lo...

Omega-3 polyunsaturated fatty acids is a generic term that encompasses eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), which are abundant in fish, and α-linolenic acid, which is abundant in perilla oil. These fatty acids became well known following an epidemiological study conducted in Greenland about 50 years ago. EPA formulations, wit...

Background The efficacy of the mindfulness-based stress management program for maintaining a better mental state has not been examined among working populations. We aimed to explore the effectiveness of the brief mindfulness-based stress management program for hospital nurses. Methods In a multi-center randomized trial, 80 junior nurses working in...

Background The dietary pattern of pregnant women is known to be associated with preterm birth (PTB). We investigated whether PTB was associated with intake of fermented food by using data from the Japan Environment and Children’s Study. Methods From a data set of 103,099 pregnancies, 77,667 cases at low risk for PTB were analyzed. The primary outc...

Background Vitamin D has been reported to affect both innate, and acquired immunity with immune cells such as dendritic cells having the vitamin D receptors. The co-occurrence of the high prevalence of allergic diseases and vitamin D deficiency globally documented in recent decades, has prompted a hypothesis on whether there is a reasonable associa...

Odds ratio (OR) and its 95% Confidence Interval (95%CI) for allergic symptom development of vitamin D deficiency in their 1st trimester. (DOCX)

Odds ratio (OR) and its 95% Confidence Interval (95%CI) for allergic symptom development of vitamin D deficiency in their 2nd trimester. (DOCX)

Odds ratio (OR) and its 95% Confidence Interval (95%CI) for allergic symptom development in Vitamin D non-deficient subjects (25(OH)D > = 20 ng/mL). (DOCX)

Serum 25(OH)D levels in relation to sampled months on subjects with/without history of allergic rhinitis. There was a clear seasonal change with a peak at the end of summer and a trough in early spring regardless of past history of allergic rhinitis. (TIFF)

Serum 25(OH)D levels in relation to sampled months on subjects seropositive/seronegative to Japanese Cedar Pollen (JCP). There was a clear seasonal change with a peak at the end of summer and a trough in early spring regardless of the presence of serum IgE to JCP. (TIFF)

Odds ratio (OR) and its 95% Confidence Interval (95%CI) for allergic symptom development on cases with sufficient in vitamin D (> = 30 ng/mL) and on cases with insufficient vitamin D (20–30 ng/mL) compared with cases deficient in vitamin D (< 20 ng/mL). (DOCX)

Odds ratio (OR) and its 95% Confidence Interval (95%CI) for allergic symptom development compared with cases deficient in vitamin D (< 20 ng/mL). (DOCX)

Following reports of epidemiological studies in Greenland in the early 1970s, n-3 polyunsaturated fatty acids （PUFAs） were investigated with high hopes for their preventive effects on atherosclerotic disease and they have now come into clinical use. Subsequently, research interest in n-3 PUFAs expanded into the field of psychiatry. A case-control stu...

Background As a consequence of indoor occupations and reduced exposure to sunlight, concerns have been raised that vitamin D deficiency is widespread in developed countries. Vitamin D is known to be associated with increased risks of morbidity and mortality in various diseases. Objective To investigate the serum vitamin D status and its relation w...

Background: Omega-3 polyunsaturated fatty acids (PUFAs) reduce depressive symptoms through an anti-inflammatory effect, and injection of both omega-3 PUFAs and estradiol (E2) induces antidepressant-like effects in rats by regulating the expression of inflammatory cytokines. The aims of this study were to examine the association of increased E2 dur...

The results of several epidemiological studies have shown a moderate association between postpartum depression (PPD) and mother-infant bonding (MIB); however, associations and changes that longitudinally considered parity were not reported. We investigated the possible association between PPD and MIB at one month after birth, in addition, the chang...

Received: August 13, 2018 Accepted: November 08, 2018 Published online: December 12, 2018 Issue release date: April 2019

Background: The pathophysiology of fear of cancer recurrence (FCR), the leading unmet psychological need of cancer survivors, may involve the dysfunctional processing of fear memory. n-3 polyunsaturated fatty acids (PUFAs) have beneficial effects on psychiatric disorders, including depressive disorder and anxiety disorders, and are involved in fear...

Objective There have been increasing reports on the association between cesarean section (C-section) and the subsequent development of diseases in infants. C-section affects the diversity of microbiota in the infant’s gut. In the present study, we investigated the association between infants delivered by C-section and the development of constipatio...

In contrast to the cumulative evidence suggesting the inverse association of n-3 polyunsaturated fatty acids (PUFAs) with depression, few studies have examined the association of n-6 PUFAs with depression. In particular, no study has examined the relationship between n-6 PUFAs and depression in cancer patients. Thus, we conducted this cross-section...

Background: This study assessed whether a combined intervention of omega-3 polyunsaturated fatty acids (PUFAs) and psychoeducation better improved mild to moderate depression in workers compared to psychoeducation alone. Methods: This study was a double-blinded, parallel group, randomized controlled trial that compared the intervention group, re...

Objective: Emerging evidence from epidemiologic studies and clinical trials indicates that ω-3 polyunsaturated fatty acids (PUFAs) may have a preventive or therapeutic effect on allergy, although the results remain controversial. The aim of this study was to investigate the association between intake of fish and ω-3 PUFAs with risk for lifetime pr...

The results of several epidemiological studies have shown a moderate association between postpartum depression (PPD) and mother-infant bonding (MIB); however, associations and changes that longitudinally considered parity were not reported. We investigated the possible association between PPD and MIB at one month after birth, in addition, the chang...

Background The aim of this study was to examine how physical activity (PA) before and during pregnancy influences pregnancy outcomes, particularly preterm delivery and mode of delivery. Methods This study was based on the Japan Environment and Children’s Study. A total of 92,796 pregnant women who gave birth to live singleton babies were included....

Maternal characteristics according to the term of delivery (n = 89,632) or the mode of delivery (n = 89,398). (XLSX)

Association between physical activity level before pregnancy and preterm delivery. *p<0.05. Adjusted for maternal age, current marital status, education, annual household income, alcohol intake during 2nd 3rd trimester, smoking status during 2nd 3rd trimester, exposure to tobbaco smoke during 2nd 3rd trimester, threatened abortion, threatened prema...

Association between physical activity level before pregnancy and mode of delivery. *p<0.05. Adjusted for maternal age, current marital status, education, annual household income, alcohol intake during 2nd 3rd trimester, smoking status during 2nd 3rd trimester, exposure to tobbaco smoke during 2nd 3rd trimester, threatened abortion, threatened prema...

Participants inclusion flowchart with regard to the analysis of physical activities before pregnancy. (TIF)

Amounts of physical activity before pregnancy (Mets・h/w). (XLSX)

The efficacy of omega-3 fatty acids for maintaining a better mental state has not been examined among working populations. We aimed to explore the effectiveness of omega-3 fatty acids for hospital nurses. In a multi-center randomized trial, 80 junior nurses were randomly allocated to either omega-3 fatty acids (1200 mg/day of eicosapentaenoic acid...

The relationship of n-3 polyunsaturated fatty acids (PUFAs) and gut microbiota with brain function has been extensively reported. Here, we review how n-3 polyunsaturated fatty acids affect fear memory processing. n-3 PUFAs may improve dysfunctional fear memory processing via immunomodulation/anti-inflammation, increased BDNF, upregulated adult neur...

Background and aims: Higher intake of fish or n-3 polyunsaturated fatty acids (PUFAs) has been associated with reduced risk of coronary heart disease (CHD). However, it is unclear whether increased blood levels of n-3 PUFAs are associated with reduced risk of CHD in the Japanese population. Methods: The relationship between circulating levels of...

The results of several epidemiological studies and clinical trials investigating the effects of n-3 polyunsaturated fatty acids (PUFAs) on antenatal and postnatal depression remain controversial. We investigated the possible association of dietary intake of fish and n-3 PUFAs with the risks of maternal and paternal psychological distress during pre...

The risk of schizophrenia is increased in offspring whose mothers experience malnutrition during pregnancy. Polyunsaturated fatty acids (PUFAs) are dietary components that are crucial for the structural and functional integrity of neural cells, and PUFA deficiency has been shown to be a risk factor for schizophrenia. Here, we show that gestational...

Systematic review of observational studies has revealed that fish consumption and levels of n-3 polyunsaturated fatty acids (PUFAs) such as eicosapentaenoic acid (EPA) and docosahexaenoic acid are associated with a reduced risk of depression. A reverse J-shaped effect of n-3 PUFAs was suggested. However, there is limited evidence from populations w...

Empirical evidence is divided on whether n-3 polyunsaturated fatty acid levels are associated with quality of life (QOL). This study investigated the effects of docosahexaenoic acid (DHA) supplementation on QOL in survivors of traumatic injury. In this secondary analysis of a double-blind, randomized controlled trial, we recruited 110 trauma patien...

Objectives: Although safe approaches for improving depression in pregnancy are required and the efficacy of omega-3 polyunsaturated fatty acids (PUFAs) has been suggested, the amount of supplemental omega-3 PUFAs has varied among previous studies and adequate amount might be different among countries. The aim of this pilot study is to explore the f...

Background: Around 20% of patients with acute coronary syndrome (ACS) develop depression. Furthermore, some observational studies revealed baseline polyunsaturated fatty acids (PUFAs) may affect the prognosis of depression after ACS. This prospective cohort study examined the association between psychiatric disorder and PUFAs after ACS. Methods:...

Background: Studies investigating the relationship between n-3 polyunsaturated fatty acid (PUFA) levels and psychiatric disorders have thus far focused mainly on analyzing gray matter, rather than white matter, in the postmortem brain. In this study, we investigated whether PUFA levels showed abnormalities in the corpus callosum, the largest area...

In this chapter we explore the physiological effects of Mead acid (5,8,11-eicosatrienoic acid, MA) on osteoblasts and osteoclasts in Part 1 and then on angiogenesis in Part 2.

The results of several epidemiological studies and clinical trials investigating the effects of n-3 polyunsaturated fatty acids (PUFAs) on antenatal and postnatal depression remain controversial. In a previous case-control study of early pregnancy in Japan, we found an inverse association between eicosapentaenoic acid and risk of psychological dist...

Background: Maternal depression can be harmful to both mothers and their children. Omega-3 polyunsaturated fatty acid (PUFA) supplementation has been investigated as an alternative intervention for pregnant women with depressive symptoms because of the supporting evidence from clinical trials in major depression, the safety advantage, and its anti...

Background: Eicosapentaenoic acid (EPA) is suggested to be protective against posttraumatic stress disorder (PTSD) from two observational studies. We previously conducted a randomized controlled trial and found no effect of docosahexaenoic acid (DHA) for prevention of PTSD. This secondary analysis aimed to determine whether change in blood levels...

Background: Psychophysiological symptoms (e.g., pounding heart) are known to be a prominent feature of post-traumatic stress disorder (PTSD). Although omega-3 polyunsaturated fatty acids (PUFAs) have a beneficial potential pharmacological effect of preventing these psychophysiological symptoms, no clinical data is yet available. Therefore, we cond...

High calcium intake may increase hip fracture (HF) incidence. This phenomenon, known as the calcium paradox, might be explained by vaccenic acid (18:1t n-7, VA), the highly specific trans fatty acid (TFA) present in dairy products. First, we ecologically investigated the relationship between 18:1 TFA intake and HF incidence using data from 12 to 13...

Background: Desert dust originating from arid and semiarid areas is transported to widespread regions, including Japan. Desert dust particles exert adjuvant effects in animals. Objectives: To examine whether desert dust enhances allergic symptoms in real-life settings and to explore its effect modifiers. Methods: We conducted an observational...

N-3 polyunsaturated fatty acids (PUFAs), especially long-chain types such as docosahexaenoic acid, are important nutrients in pregnancy, but the relationship between n-3 PUFA levels and perinatal and postnatal depression remains controversial. This study examined the possible relationship between serum n-3 PUFA levels and psychological distress amo...

Background: Abnormal levels of n-3 polyunsaturated fatty acids (PUFAs), particularly docosahexaenoic acid (DHA), have been found in the postmortem frontal cortex, particularly the orbitofrontal cortex, of patients with schizophrenia. Altered mRNA expression of fatty acid binding protein (FABP) 5 and FABP7 has likewise been reported. Methods: Thi...

Background: Emerging evidence suggests that fish consumption may have beneficial effects on mood disorders. However, no study has been reported on this issue in young adults to date. The aim of this study was to investigate the relationship between fish consumption and depressive symptoms in Japanese undergraduate students. Methods: The 20-item...