Vitamin B5 biomarkers in human milk reveal mammary gland function

Researchers have identified new biomarkers in human milk that reflect mammary gland activity, linking maternal nutrition directly to infant growth. The analysis of 1,543 human milk samples from Canada, Pakistan, and Burkina Faso revealed shared molecular patterns tied to maternal nutritional status.

The research examined thousands of molecular features associated with core mammary functions. These included milk synthesis and secretion, epithelial barrier and tissue remodeling, and immune and repair activity. The team combined multiple molecular layers from geographically diverse populations. They used metabolites, proteins, micronutrients, macronutrients, and human milk oligosaccharides.

Computational approaches and infant growth data helped pinpoint seven candidate biomarkers. These molecules are linked to maternal nutrition, infant development, and mammary gland function. Human milk can be collected repeatedly. This offers a noninvasive way to study the biology of the lactating breast over time. The mammary gland undergoes extensive transformation during pregnancy, but lactation only becomes apparent after birth. It acts as a critical postnatal maternal-infant interface.

Liat Shenhav, Ph.D., senior author of the study, said: "Human milk gives us a rare, noninvasive window into the biology of the lactating mammary gland."

Acylcarnitines and vitamin B5 emerge as key signals

Seven candidate biomarkers were identified in the analysis. Four were short-chain acylcarnitines.

Short-chain acylcarnitines showed the strongest links across mammary functional domains. C5 emerged as a particularly prominent signal. Higher levels of C5 were associated with reduced signatures of milk synthesis. They also correlated with biological patterns related to tissue remodeling and immune activity.

The researchers propose a metabolic bottleneck. Acylcarnitine metabolism depends on coenzyme A (CoA), which is synthesized from pantothenic acid, or vitamin B5. Low vitamin B5 availability may constrain this CoA-dependent metabolism and contribute to the altered acylcarnitine profiles observed.

Findings part of larger global milk composition effort

This study is one of two companion papers published in the journal Science on October 8, 2026. They originate from the International Milk Composition (IMiC) Consortium. The IMiC effort brought together more than 1,000 mother-infant pairs. It profiled more than 25,000 molecular features in human milk.

The companion study found that maternal supplementation during lactation increased several B vitamins in milk. Many other milk components remained comparatively stable. In two randomized nutritional trials, maternal supplementation promoted recovery or stability among infants at higher risk for poor growth.

Research team and institutional support

The study was led by researchers at NYU Grossman School of Medicine. Dr. April Jauhal is the first author from the Shenhav lab. Additional authors included Bianca Cordazzo-Vargas, Daniel Sunko, and Pratima Niroula. The work was supported by a wide array of international funders including the Gates Foundation, the National Institutes of Health, and the Canadian Institutes of Health Research.

Dr. April Jauhal said: "Our findings demonstrate the intimate link between maternal nutrition, metabolic health and mammary function."

The Shenhav lab is now developing an integrated computational and experimental framework. Its goal is to test potential nutritional bottlenecks, specifically the vitamin B5-coenzyme A-C5 pathway. The lab is also studying colostrum and transitional milk. This work aims to understand how mammary functional states emerge during the transition from pregnancy to mature lactation.