Study identifies seven molecules in human milk linked to baby growth

An international research team has pinpointed seven molecules in human milk that may explain the link between a mother's nutrition and her infant's growth. The findings, published in the journal Science, offer new insights into the biology of the milk-producing mammary gland. The study analyzed 1,543 milk samples from mothers in Canada, Pakistan and Burkina Faso. It was led by researchers at NYU Grossman School of Medicine as part of the International Milk Composition Consortium. "Human milk gives us a rare, non-invasive window into the biology of the lactating mammary gland," said Liat Shenhav, the study’s senior author and an assistant professor at NYU Grossman School of Medicine. The consortium's work involved more than 1,000 mother-infant pairs and profiled over 25,000 molecular features. By examining diverse populations, Shenhav said researchers can begin to understand how a mother's nutritional state relates to milk composition and infant growth.

The researchers used a method called multi-omics to study several types of molecules together, including metabolites, proteins, vitamins and complex sugars. They combined these measurements with infant growth data using computational tools like machine learning. In two separate nutritional trials, supplements given to mothers were associated with improved or stable growth in infants at higher risk of poor growth. The analysis found a shared pattern in milk composition linked to both supplementation and infant growth.

The seven key molecules are four short-chain acylcarnitines (C2, C3, C4, and C5), the amino acid lysine, the complex sugar 6′ sialyllactose, and the mineral selenium. Acylcarnitines help cells process nutrients for energy. Among them, C5 showed the strongest connections to various functions of the mammary gland. Higher levels of C5 were associated with signs of reduced milk synthesis and with patterns related to tissue remodeling and immune activity.

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The prominence of C5 led the team to explore a potential link to maternal nutrition. The metabolism of acylcarnitines depends on coenzyme A, which the body produces from vitamin B5. The researchers proposed that a shortage of vitamin B5 could disrupt this process and lead to an accumulation of C5. "One plausible route linking maternal nutrition to mammary metabolism in our data is via the pantothenic-CoA-C5 metabolic pathway, and we are currently investigating the functional role of this pathway in mammary biology and lactation," said first author Dr. April Jauhal of the Shenhav lab.

A companion study in the same journal found that maternal supplementation during lactation increased several B vitamins in milk, while many other components remained stable. "The studies show that human milk is neither fixed nor simply a reflection of what a mother eats," said Shenhav. She explained that some components respond to nutrition, while others reflect broader biological states within the gland. The Shenhav Lab is now developing a research framework to test potential nutritional bottlenecks in milk production, including the pathway involving vitamin B5 and C5. "Ultimately, we want to understand milk in the context of the biology that produces it," said Shenhav. The lab is also studying early milk types, like colostrum, to understand how the mammary gland's function changes from pregnancy through lactation.

With files from SciTechDaily