Insulin plays an important role in making breast milk, according to a new study that may help explain why many mothers have difficulty producing enough milk to nurse their baby.
The researchers describe how milk-producing glands become highly sensitive to insulin during lactation and how specific genes in the glands are switched on during lactation.
RNA sequencing technology revealed "in exquisite detail" the blueprint for milk production in the mammary glands, said study corresponding author Laurie Nommsen-Rivers, a scientist at Cincinnati Children's Hospital Medical Center.
The findings were published online on 5 July in the journal PLoS One.
"This new study shows a dramatic switching on of the insulin receptor and its downstream signals during the breast's transition to a biofactory that manufactures massive amounts of proteins, fats and carbohydrates for nourishing the newborn baby," Nommsen-Rivers said in a medical centre news release.
In previous research, Nommsen-Rivers found that new mothers with characteristics linked to poor glucose metabolism – such as being overweight, older or having a large baby – take longer to begin producing milk. This suggested that insulin was a factor in milk production.
"Considering that 20% of women between 20 and 44 are prediabetic, it's conceivable that up to 20% of new mothers in the United States are at risk for low milk supply due to insulin dysregulation," she added.
Nommsen-Rivers and her colleagues are planning a study to determine if a drug used to control blood sugar in people with type 2 diabetes boosts insulin action in mammary glands and improves milk supply.
"The ideal approach is a preventive one," she said. "Modifications in diet and exercise are more powerful than any drug. After this clinical trial, we hope to study those interventions."
The American Academy of Family Physicians offers breast-feeding tips.