Chrononutrition and Breast Milk: A Review of the Circadian Variation of Hormones Present in Human Milk

Introduction: Breast milk contains a wide range of hormones, nutrients, and bioactive compounds. Chrononutrition looks at the interaction between food, both meal timing and meal composition, and circadian rhythms. Method: This review is a continuation on series on chrononutrition and breast milk. All human studies published in English were included regardless of location or year of publication. Results: This review identifies the hormonal circadian variation researched in breast milk to date for melatonin, cortisol, cortisone, leptin, and insulin. Conclusion: The circadian variation observed in some hormones reinforces the superiority of breast milk over formula milk. Melatonin has been the most studied, but more research for all the hormones is needed due to various gaps in the literature and varying levels of study quality. There is insufficient evidence to make recommendations specifically targeting the lactating mother, but we identify and recommend several ideas for future research.