J Appl Biomed 11:59-70, 2013 | DOI: 10.2478/v10136-012-0020-0

Evolution of the circadian profile of human milk amino acids during breastfeeding

Cristina Lucía Sánchez^1,2,*, Javier Cubero³, Javier Sánchez⁴, Lourdes Franco², Ana Beatriz Rodríguez², Montserrat Rivero⁵, Carmen Barriga²

¹ Translational Neuroscience in Psychiatry and Neurology, Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, RWTH Aachen University, Germany

² Chrononutrition Laboratory, Department of Physiology, Faculty of Science, University of Extremadura, Spain

³ Health Education Laboratory, Experimental Sciences Education Area, University of Extremadura, Spain

⁴ Metabolism Laboratory, Perpetuo Socorro Hospital, Servicio Extremeño de Salud (SES), Badajoz, Spain

⁵ Scientific Division Manager, Ordesa Group, Barcelona, Spain

Human milk is a living fluid that changes with time, composition and volume. Circadian rhythms regulate a variety of biological processes in living organisms; and perhaps the most evident function is the sleep-wake cycle. The aim of the present study was to evaluate the circadian rhythm of breast milk amino acids and their evolution throughout the breastfeeding period. Human breast milk samples from 77 donors were collected every 3 hours over a 24-h period. The rhythmicity of the amino acids was determined by cosinor analysis. Colostrum samples showed no circadian rhythm in most amino acids except tryptophan. However, daily variations were observed in tryptophan and methionine at transitional phase, according to the newborn's pattern of intake every 3 hours regardless of whether it is day or night. During the last stage (mature milk), when breast milk has fully stabilized, most amino acids showed a circadian rhythm. In conclusion, breast milk should be given to the baby at the same time of day it is expressed. Thus, the baby would be adjusting its circadian pattern in harmony with his environment (day/night), which is crucial for the proper functioning and synchronization of all systems in the human body.

Keywords: amino acids; day, night; circadian rhythm; human milk; tandem mass

Received: June 19, 2012; Revised: October 10, 2012; Published: July 31, 2013  Show citation