Associations Between Habitual Dietary Behaviors and Glutamic Acid Levels in Human Milk

Background: Glutamic acid, an amino acid that exhibits umami taste, is utilized in Japanese food and is abundant in human milk. We examined the influence of maternal habitual eating behavior on glutamic acid concentration in human milk. Research Aim: To determine the association between maternal dietary behaviors at the end of pregnancy and the 1st month postpartum and glutamic acid concentration in colostrum and mature milk. Method: This was a prospective, correlational, one-group longitudinal study. Women aged 20–30 years during the third trimester of pregnancy (N = 30) consented to participate and completed the data collection. Dietary history questionnaires were used to measure food intake. Glutamic acid levels in whey from colostrum and mature milk and in plasma during late pregnancy and the first month postpartum were measured. Data were considered significant at p < .05. Basic statistics, correlation coefficients analysis, unpaired t test, and one-way analysis of variance were performed. Results: Glutamic acid concentrations in human milk and plasma were found to be significantly associated with the consumption of several different foods. There was no association between glutamic acid concentrations in human milk and plasma or between glutamic acid concentrations in colostrum and mature milk. The glutamic acid content of mature milk differed by physical activity level (mild and moderate) during the first month postpartum (t [46] = 2.87, p < .01). Conclusion: There was no clear association between habitual dietary behavior and glutamic acid concentration in human milk. However, maternal factors other than diet may be important and require additional research.