Human milk micronutrients and child growth and body composition in the first 2 years: A systematic review

Authors: REYES, SARAH - University Of Manitoba; BROCKWAY, MEREDITH (MERIL - University Of Manitoba; MCDERMID, JOANN - University Of Virginia; CHAN, DEBORAH - McGill University - Canada; GRANGER, MATTHEW - University Of Manitoba; REFVIK, REBECCA - University Of Manitoba; SIDHU, KARANBIR - University Of Manitoba; MUSSE, SAUD - University Of Manitoba; MONNIN, CAROLINE - University Of Manitoba; LOTOSKI, LARISA - University Of Manitoba; GEDDES, DONNA - University Of Western Australia; JEHAN, FYEZAH - Aga Khan University; KOLSTEREN, PATRICK - Ghent University; Allen, Lindsay; HAMPEL, DANIELA - University Of California, Davis; ERIKSEN, KAMILLA - University Of Copenhagen; RODRIGUEZ, NATALIE - University Of Manitoba; AZAD, MEGHAN - University Of Manitoba

Submitted to: Advances in Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/7/2023
Publication Date: 1/18/2024
Citation: Reyes, S.M., Brockway, M., McDermid, J.M., Chan, D., Granger, M., Refvik, R., Sidhu, K.K., Musse, S., Monnin, C., Lotoski, L., Geddes, D., Jehan, F., Kolsteren, P., Allen, L.H., Hampel, D., Eriksen, K.G., Rodriguez, N., Azad, M.B. 2024. Human milk micronutrients and child growth and body composition in the first 2 years: A systematic review. Advances in Nutrition. 15(1). Article 100082. https://doi.org/10.1016/j.advnut.2023.06.005.
DOI: https://doi.org/10.1016/j.advnut.2023.06.005

Interpretive Summary: Human milk (HM) provides many compounds that support infant development. Their concentrations vary greatly by mothers and across lactation. To date, we have little knowledge regarding their impact on infant growth. Here, we did a systematic search to gather the information published between 1980-2020 on HM components and anthropometry through 2 years of age among term-born infants. Measurements included were weight-for-length, length-for-age, weight-for-age, BMI-for-age, and growth rate. Of the 8,884 abstracts we found, 122 articles were included and categorized based on their reporting of HM micronutrients, macronutrients, or bioactive components. Here, we are reporting on the HM micronutrients (vitamins and minerals) based on 23 articles involving 1,836 mother-infant pairs. Studies varied in their designs, sampling times, geographic and socioeconomic settings, reporting practices, and in the HM analytes, and infant anthropometrics measured. Meta-analysis was not possible because of the small amount of available data. Most reports were on zinc (12 articles) and calcium (6 articles). HM iodine, manganese, calcium, and zinc were positively associated with several infant outcomes, while magnesium was negatively related to linear growth during early lactation. Only a few studies measured HM intake, adjusted for confounders, provided adequate information about complementary and formula feeding, or adequately described HM collection protocols. While HM micronutrients are likely affected by other HM components, only one study analyzed data on multiple micronutrients and few addressed other HM components. Thus, the available information is inconclusive and fails to address the complexity of HM. More research is required to understand HM components and their interrelationships, and how they impact infant growth, to inform future maternal, newborn, or infant nutritional interventions.

Technical Abstract: Human milk (HM) provides a plethora of nutritional and non-nutritional compounds that support infant development. For many compounds, concentrations vary substantially among mothers and across lactation, and their impact on infant growth is poorly understood. We systematically searched Medline, EMBASE, the Cochrane Library, Scopus, and Web of Science to synthesize evidence published between 1980-2020 on HM components and anthropometry through 2 years of age among term-born infants. Outcomes included weight-for-length, length-for-age, weight-for-age, BMI-for-age, and growth velocity. From 8,884 abstracts screened, 122 articles were included and categorized based on their reporting of HM micronutrients, macronutrients, or bioactive components. Micronutrients (vitamins and minerals) are reported here, based on 23 articles involving 1,836 mother-infant dyads. Studies varied markedly in their designs, sampling times, geographic and socioeconomic settings, reporting practices, and in the HM analytes and infant anthropometrics measured. Meta-analysis was not possible because data were sparse for most micronutrients. The most-studied micronutrients were zinc (12 articles, 1,131 dyads) and calcium (6 articles, 631 dyads). HM iodine, manganese, calcium, and zinc were positively associated with several outcomes, while magnesium was negatively associated with linear growth during early lactation. However, few studies measured HM intake, adjusted for confounders, provided adequate information about complementary and formula feeding, or adequately described HM collection protocols. Only 4 studies (17%) had high overall quality scores. The biological functions of individual HM micronutrients are likely influenced by other HM components; yet only one study analyzed data from multiple micronutrients simultaneously and few addressed other HM components. Thus, available evidence on this topic is largely inconclusive and fails to address the complex composition of HM. High-quality research employing chronobiology and systems biology approaches is required to understand how HM components work independently and together to influence infant growth, and to identify new avenues for future maternal, newborn, or infant nutritional interventions.