Background: Breast milk is considered the optimal source of nutrition during infancy. Although the vitamin D concentration in human breast milk is generally considered poor for infants, vitamin D in breast milk is an important source for exclusively breastfed infants. Increases in vitamin D insufficiency and deficiency in lactating mothers may reduce vitamin D concentrations in breast milk. This study aimed to compare vitamin D and 25-hydroxyvitamin D (25OHD) concentrations in breast milk collected in 1989 and 2016–2017 and simultaneously analyze them with liquid chromatography-tandem mass spectrometry (LC-MS/MS); the association between the lifestyle of recent lactating mothers (2016–2017) and vitamin D status in human breast milk was also evaluated. Method: Lactating mothers were recruited from three regions of Japan in 1989 (n = 72) and 2016–2017 (n = 90), and milk from 3–4 months was collected in summer and winter. The samples were strictly sealed and stored at −80℃ until measurement. Breast milk vitamin D and 25OHD concentrations were analyzed by LC-MS/MS. Vitamin D intake, sun exposure, and sunscreen use of the lactating mothers in 2016–2017 were assessed. Results: Both vitamin D and 25OHD concentrations in breast milk were higher in the summer regardless of the survey year. Significantly lower vitamin D and 25OHD concentrations were observed in 2016–2017 compared with 1989 in summer, but no survey year difference was observed in winter. The stepwise multiple regression analyses identified season, daily outdoor activity, and suntan in the last 12 months as independent factors associated with vitamin D₃ concentrations. Conclusion: The results suggest that low vitamin D status in recent lactating mothers may have decreased vitamin D and 25OHD concentrations in breast milk compared with the 1980s. These results are helpful for developing public health strategies to improve vitamin D status in lactating mothers and infants.

It is unknown whether maternal health and nutrition are related to human milk composition or growth and development of infants and children. Here, we describe a protocol for a prospective five-year cohort study to clarify (i) how maternal health and nutrition, socioeconomic factors, and lifestyles affect human milk composition, and (ii) whether these are associated with growth and development of infants and children. In our study, we recruited 1210 Japanese mothers with singleton pregnancies from 73 obstetrics clinics and hospitals across Japan, between 2014 and 2019. We will measure the following: health information regarding maternal-child dyads using a self-administered questionnaire, maternal nutrition during breastfeeding using a Brief self-administrated Diet History Questionnaire, the development of infants and children using the Kinder Infant Development Scale, and the stress related to child rearing using the Mother’s Child Care Stress Scale. Simultaneously, we will collect human milk every 2 months during the first year after birth to measure its composition and levels of macronutrients. This study will generate useful data to investigate whether health status, nutritional status, lifestyle, and socioeconomic factors affect human milk composition and the growth and development of infants and children.

This study investigated whether parenting stress is associated with breastfeeding type (exclusive or partial). Between 2014 and 2019, we recruited 1210 healthy mothers (mean age, 31.2 years; 65%, multiparity) from 73 obstetric institutions across all prefectures of Japan. Among these, 1120 mothers at two months and 1035 mothers at six months were investigated for parenting stress and breastfeeding type: exclusive versus otherwise (partial). Parenting stress was measured by a validated Japanese scale consisting of childcare exhaustion, worry about child’s development, and no partner support. Exclusive breastfeeding prevalence was 75% at two and 78% at six months. The total scores for childcare exhaustion and worry about child development were statistically higher in the partial breastfeeding group than in the exclusive breastfeeding group at two months but not at six months. A logistic regression model demonstrated that childcare exhaustion was significantly associated with an increased risk of having partial breastfeeding at two months after adjusting for the maternal Body Mass Index, parity, and baby’s current weight. However, the association was no longer significant at six months. The present study suggests that intervention for parenting stress at two months postpartum may promote prolonged exclusive breastfeeding.

Human milk (HM) macronutrients are vital for infant growth and development; their composition may vary according to maternal and infant characteristics and differ across populations. However, the wide range of maternal and infant factors affecting HM macronutrient content among Japanese mothers has not been sufficiently evaluated. We comprehensively examined the factors associated with the macronutrient content of mature HM in a cross-sectional analysis of a large Japanese cohort. A cross-sectional analysis was conducted using baseline data from the Japanese HM Study cohort (n = 1071). Macronutrient and energy contents were assessed in mature HM samples collected at an average of 2 mo postpartum. Maternal and infant factors were obtained via self-reported questionnaires. Linear regression analyses were performed to identify associations between these factors and HM macronutrient and energy contents. Multivariable linear regression revealed significant associations between HM composition and several maternal and infant factors. True protein content was negatively associated with days postpartum [days; partial regression coefficient (B) = −0.0036, P < 0.001] and exclusive breastfeeding (B = −0.1045, P < 0.001). Carbohydrate content was positively associated with exclusive breastfeeding (B = 0.0963, P < 0.001). Fat content had a positive association with maternal overweight or obesity (B = 0.4648, P = 0.008) and negative associations with birth weight (g; B = −0.0002, P = 0.043) and days postpartum (days; B = −0.0103, P < 0.001). Crude protein and energy contents showed patterns similar to those of true protein and fat, respectively. For Japanese mothers, the macronutrient and energy contents of mature HM were associated with exclusive breastfeeding, maternal overweight or obesity, infant birth weight, and days postpartum. This trial was registered at https://center6.umin.ac.jp/cgi-open-bin/icdr_e/ctr_view.cgi?recptno=R000017649 as UMIN000015494.

The causality and mechanism of dietary effects on brain aging are still unclear due to the long time scales of aging. The nematode Caenorhabditis elegans has contributed to aging research because of its short lifespan and easy genetic manipulation. When fed the standard laboratory diet, Escherichia coli , C. elegans experiences an age-dependent decline in temperature-food associative learning, called thermotaxis. To address if diet affects this decline, we screened 35 lactic acid bacteria as alternative diets and found that animals maintained high thermotaxis ability when fed a clade of Lactobacilli enriched with heterofermentative bacteria. Among them, Lactobacill us reuteri maintained the thermotaxis of aged animals without affecting their lifespan and motility. The effect of Lb. reuteri depends on the DAF-16 transcription factor functioning in neurons. Furthermore, RNA sequencing analysis revealed that differentially expressed genes between aged animals fed different bacteria were enriched with DAF-16 targets. Our results demonstrate that diet can impact brain aging in a daf-16 dependent manner without changing the lifespan.

Purpose: This exploratory study examined the associations of human milk oligosaccharides (HMOs) and N-/O-glycans in human milk with infectious and allergic outcomes during infancy. Methods: This prospective cohort study included 200 Japanese mother–infant dyads selected from the Japanese Human Milk Study Cohort. Human milk samples were collected at 1–2 months postpartum, and 11 HMOs and 28 N-/O-glycans were measured. HMOs were measured as absolute concentrations, whereas N-/O-glycans were expressed as relative abundances based on normalized LC–MS signal intensity. Infant histories of infections and allergies during the first year of life were assessed using self-administered questionnaires. Associations between milk glycan components and infant health outcomes were evaluated using Firth’s penalized likelihood logistic regression. To aid interpretation of multiple glycan-outcome comparisons, q values were calculated within each outcome at each step of the hierarchical analysis using the Benjamini–Hochberg procedure for controlling the false discovery rate. Results: In Firth logistic regression analyses, several milk glycans showed nominal associations with infectious or allergic outcomes. Total sialic acid, disialylated N-glycans (N51 and N57), and 6′-sialyllactose showed nominal associations with lower odds of bronchitis, whereas total HMO showed a nominal association with higher odds of otitis media. However, no individual HMO showed a nominal association with this outcome. For food allergy, 3-fucosyllactose, lacto- N -fucopentaose II, and fucosyl-sialyl O-glycan (O24) showed nominal associations with lower odds, whereas 2′-fucosyllactose showed a nominal association with higher odds in the overall analysis. However, all infants who developed food allergy were born to secretor mothers, and several food allergy findings were attenuated in the analysis restricted to secretor mothers. For atopic dermatitis, high-mannose–type N-glycans, particularly N12 and N33, showed nominal associations with higher odds. No glycan-outcome association had a q value below 0.05 within each outcome and step of the hierarchical analysis. Conclusion: Several human milk glycans showed nominal associations with infectious or allergic outcomes during infancy. However, none had a q value below 0.05 after false discovery rate correction. These findings should be interpreted as exploratory and hypothesis-generating and require validation in larger independent cohorts.