MELK study: an observational study on human milk composition and infant health determinants during the first year of life in a Dutch cohort.

INTRODUCTION

Human milk plays a crucial role in infants' nutrition and immunity, with its composition being influenced by different factors. The role of maternal diet on human milk fatty acid composition, especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), is well studied. Higher fish intake is associated with higher DHA levels in human milk, while fewer associations have been reported for EPA. Yet, maternal diet's impact on human milk composition for other nutrients is understudied, and variations in sampling protocols and study quality hinder definitive conclusions on its overall impact. Ethnicity may also impact milk composition, with different dietary habits intertwined with different genetic backgrounds, but also here research lacks standardised protocols. Our study aims to investigate maternal diet, ethnicity, and their association with human milk composition, along with their potential short-term associations with infant health and development, through detailed dietary assessment and by recruiting participants from diverse backgrounds. Understanding these associations could inform the development of tailored nutritional guidelines for mothers and infants, ultimately promoting optimal health and well-being for both. The study design, with its strict sampling procedure, can guide and inspire future studies.

METHODS AND ANALYSIS

We will conduct an observational study involving 120 healthy mothers from three ethnic backgrounds (Chinese, Caucasian and Turkish), exclusively breastfeeding their 2-month-old infants. We will collect human milk samples at two time points and assess maternal dietary intake over 4 days. Additionally, we will collect data on various maternal and child characteristics, including maternal stress, socioeconomic status and health, and infant feeding, sleeping, crying, gastrointestinal health and developmental status.

ETHICS AND DISSEMINATION

The study has been approved by the Medical Ethical Committee Oost-Nederland (NL79447.091.21), and all participants provided written informed consent before entering the study. Findings will be widely disseminated at international conferences and meetings including the annual Nutrition & Growth conference, ESPGHAN, and through publication in scientific peer-reviewed journals.

TRIAL REGISTRATION NUMBER

ISRCTN registry (ISRCTN35735283).