Circadian changes in the composition of human milk macronutrients depending on pregnancy duration: a cross-sectional study

Abstract

Background The purpose of this study was to evaluate the circadian variation of human milk macronutrients and energy content depending upon pregnancy duration. Methods One hundred eighty fresh human milk samples from 45 mothers (27 of preterm and 18 of full-term newborns) were collected on a single day chosen between the 14th to 16th day after delivery. The samples were taken four times per day at 12 PM, 6 PM, 12 AM and 6 AM. Only lactating women, who could not breastfeed their hospitalized newborns and expressed milk by breast pump, were enrolled in the study. Human milk macronutrient composition and energy count were evaluated by mid-infrared spectrophotometry. Results Significant differences in macronutrient content were observed between 6 AM and 12 PM for mean protein content (t = − 4.62, df = 44, p < 0.001), for mean fat content (t = − 2.10, df = 44, p = 0.04) and for mean energy content (t = − 2.24, df = 44, p = 0.03); between 6 AM and 6 PM for mean protein content (t = − 2.41, df = 43, p = 0.02), for mean fat content (t = − 3.76, df = 43, p = 0.001) and for mean energy content (t = − 3.85, df = 43, p < 0.001); between 12 PM and 12 AM for mean protein content (Wilcoxon test V = 75.5, p = 0.001), for mean fat content (t = 2.50, df = 44, p = 0.02) and for mean energy content (t = 2.74, df = 44, p = 0.01); between 6 PM and 12 AM for mean protein content (V = 229, p = 0.02), for mean fat content (t = 4.39, df = 43, p < 0.001) and for mean energy content (t = − 4.57, df = 43, p < 0.001). The average content of carbohydrates did not change significantly during the 24 h. The samples of preterm newborns’ mothers had more apparent diurnal fluctuations in macronutrient content. Conclusions Our study revealed significant diurnal variations in protein and fat in human milk, and these circadian fluctuations were more apparent in the milk of mothers of preterm infants.

Cellular and transcriptional diversity over the course of human lactation

“…Donors expressed milk using their method of choice and, where possible, provided that information in questionnaires for each sample. To minimize diurnal variations in cell composition, donors provided milk in the mornings between 6:00 AM and 9:00 AM ( 74 , 75 ). We also collected extensive donor-supplied metadata for each sample ( Dataset S1 ), including information about maternal and infant health.…”

Temporal Changes in Breast Milk Fatty Acids Contents: A Case Study of Malay Breastfeeding Women

“…Throughout the milk collection period, milk samples were collected in the morning to standardise the timing of collection and to minimise circadian effects on milk composition [17]. Before collecting milk sample, the nipples and areolas of the breast were cleaned with 70% alcohol ethyl alcohol.…”

Breast Milk and the Importance of Chrononutrition

“…Ghrelinisalso present in human milk as well as insulin, adiponectin, obestatin, and other metabolic hormones ( 15 , 41 ). No diurnal differences have been found among these latter hormones or in total proteins, carbohydrates, and lactose, or there are controversies about their diurnal differences ( 42 , 43 ). However, of 17 amino acids explored, only a clear rhythm of tryptophan was observed in colostrum, transitional, and mature human milk with an acrophase at approximately 0400 h, and then its levels decrease and reach a nadir during the afternoon ( 7 ).…”