Researchers Identify Molecules Associated with Low Volume of Breast Milk

05/11/2023
By Karen Angelo

Studies show that about 40% percent of mothers who breastfeed report weaning their babies sooner than planned due to concerns about producing enough milk and nutrient deficiencies in their milk. Federal dietary guidelines recommend breastfeeding exclusively for the first six months, with continued breastfeeding while introducing appropriate foods for a year or longer. 

“While breast milk is conditionally perfect for babies, many factors affect milk composition and production,” says Prof. Shannon Kelleher of the Biomedical and Nutritional Sciences Department. 

That’s why Kelleher researches mothers’ diets, genetics and environmental exposures. 

In her latest study, Kelleher and her research team identified molecules in human milk for the first time that may be responsible for regulating milk volume. 

Results of the study, recently published in the journal Nutrients, shed light on the role of molecules called miRNAs that regulate gene expression. The research involved 221 women from ages 19 to 42 who planned to breastfeed for at least six months. 

“Our study shows that a miRNA called let-7g-5p is significantly higher in the first week of lactation of women who have a low milk supply, compared to those who have an adequate supply,” says Kelleher, who conducted the research with colleagues from Penn State College of Medicine as well as UMass Lowell students. “We also found that mothers with low fruit intake had higher levels of the let-7g-5p.” 

Kelleher and the research team believe that milk can be used as a “liquid biopsy” of the lactating mammary gland to understand if the gland is working properly. 

“By measuring milk levels of let-7g-5p during the first weeks after birth, caregivers could identify women who need additional lactation support,” says Kelleher. “These interventions may include dietary changes, lactation consultant support, medications and therapy.” 

Biomedical Engineering and Biotechnology master’s student Anna Ward, who co-authored the paper, demonstrated in cultured mammary cells in vitro that elevated levels of let-7g-5p are associated with low milk supply. 

“This is an exciting avenue for future research because of its potential role in maintaining optimal breast function and adequate milk supply,” says Ward, who earned her undergraduate degree in applied biomedical sciences at UML in 2020. “By understanding biological factors that contribute to low milk supply, we can look for ways to target or modify these factors.” 

One of the opportunities for improvement may be in the diet, says Kelleher. The researchers assessed the diet of the mothers who participated in the study and discovered that low fruit intake was associated with high let-7g-5p levels and low milk volume. This suggests to Kelleher and her team that polyphenols, a family of compounds found in fruit and vegetables, may modulate levels of let-7g-5p. 

“Increasing a mother’s fruit intake could make a big difference to mothers who want to nurse their babies,” says Kelleher. 

Under the direction of Kelleher, applied biomedical sciences student Serena Burkinshaw ’23 is studying the effect of polyphenols on mammary cells for her honors project. 

“I have been working with Dr. Kelleher on a literature review on the effect of polyphenols on women, animal models and mammary cells in culture,” says Burkinshaw, who plans on continuing as a master’s student in the applied biomedical sciences program and eventually working for a pharmaceutical or biotechnology company. “We are examining the effect of grape-seed extract, which contains a variety of polyphenols, on mammary epithelial cells to understand the mechanism by which polyphenols may affect let-7g-5p levels and milk supply.”