Scientists discovered that two special hormones found in breast milk—prolactin and oxytocin—help babies’ intestines work properly and absorb nutrients. Researchers tested these hormones on intestinal tissue in the lab to see how they affect the gut’s ability to move food along and take in glucose (a type of sugar). They found that each hormone alone helped the intestines absorb more glucose, but when combined, they actually reduced absorption. This research helps explain why breast milk is so important for babies’ digestive health and development during their first months of life.
The Quick Take
- What they studied: How two hormones naturally found in breast milk (prolactin and oxytocin) affect how babies’ intestines move food and absorb nutrients like glucose
- Who participated: This was a laboratory study using intestinal tissue samples, not human volunteers. The researchers tested different concentrations of the hormones on tissue from different parts of the small intestine
- Key finding: When prolactin and oxytocin were tested separately, they each helped intestines absorb more glucose. But when combined together, they actually reduced glucose absorption, suggesting the body has a special way of controlling nutrient uptake
- What it means for you: This research suggests breast milk’s hormones play an important role in helping babies’ digestive systems develop properly. However, this is early laboratory research, so more studies in actual babies are needed before making any health recommendations
The Research Details
Scientists took small pieces of intestinal tissue and placed them in a special solution that mimics the body’s environment. They attached these tissue samples to sensitive machines that could measure how much the intestines contracted (squeezed). Then they added different amounts of prolactin, oxytocin, or both hormones to see how the tissue responded. They also measured how much glucose the tissue absorbed and how much of a chemical called nitric oxide was produced. This type of laboratory testing allows researchers to study how hormones affect intestinal function in a controlled way.
By studying intestinal tissue directly in the lab, scientists can understand the exact mechanisms of how breast milk hormones work on the gut. This controlled approach helps identify what each hormone does individually and how they interact together, which would be impossible to study safely in babies. Understanding these mechanisms helps explain why breast milk is beneficial for infant development.
This is a laboratory-based study using tissue samples rather than living subjects, which means the results show what’s possible but may not exactly match what happens in a real baby’s body. The study was published in a peer-reviewed scientific journal, which means other experts reviewed the work. However, because this is early-stage research, the findings need to be confirmed with additional studies before being applied to infant nutrition recommendations
What the Results Show
The researchers found that prolactin and oxytocin both affected how the intestines contracted, but the effects varied depending on which part of the small intestine was tested. Oxytocin produced higher levels of nitric oxide (a chemical that helps relax muscles) compared to prolactin. When the two hormones were tested together, they reduced the intestines’ contractions more than either hormone alone, and they also reduced nitric oxide production in some parts of the intestine but not others. Most importantly, prolactin and oxytocin each individually increased how much glucose the intestinal tissue could absorb, but when combined, they actually decreased glucose absorption. This suggests the body has a sophisticated system for controlling how much nutrition babies absorb from breast milk.
The study found that different parts of the small intestine (duodenum, jejunum, and ileum) responded differently to these hormones. The combination of prolactin and oxytocin reduced nitric oxide production in the first two sections but not in the last section. This variation suggests that breast milk hormones have specialized effects depending on where in the intestine they act, which may be important for different stages of nutrient absorption
Previous research has shown that prolactin and oxytocin support immune function and gut development in infants, but the specific details of how they affect intestinal movement and nutrient absorption were not well understood. This study fills that gap by showing the direct effects of these hormones on intestinal function. The finding that the hormones work differently when combined is new and suggests the body uses these hormones in a coordinated way to regulate digestion
This study used intestinal tissue in a laboratory rather than studying living babies, so the results may not perfectly match what happens in a real digestive system. The study didn’t involve human subjects, so we don’t know if these effects occur the same way in actual infants. Additionally, the study measured specific chemical responses but didn’t track overall digestive health or nutrient status. More research in actual babies would be needed to confirm these findings apply to real-world infant nutrition
The Bottom Line
Based on this research, there are no new recommendations for parents at this time. The findings support the existing evidence that breast milk is beneficial for babies’ digestive development, but this is laboratory research that needs further confirmation. Parents should continue following their pediatrician’s guidance on infant feeding. (Confidence level: Low—this is early-stage research)
This research is most relevant to pediatricians, infant nutrition specialists, and scientists studying how breast milk supports baby development. Parents of infants may find it interesting as it explains some of the science behind why breast milk is recommended, but it doesn’t change current feeding guidelines. This research is not applicable to older children or adults
This is basic science research, so there’s no immediate timeline for practical benefits. It typically takes many years of additional research before laboratory findings lead to changes in medical recommendations or products
Want to Apply This Research?
- If tracking infant feeding, note the type of feeding (breast milk, formula, or combination) and observe general digestive health markers like stool consistency and feeding frequency to correlate with overall infant wellness
- For parents using a nutrition app, this research reinforces the importance of tracking breast milk feeding duration and frequency as part of infant health monitoring. Consider logging any digestive observations alongside feeding data
- Long-term tracking could include monitoring infant growth patterns, digestive comfort, and feeding milestones in relation to feeding type, which may help parents and pediatricians understand individual infant responses to different feeding approaches
This research is laboratory-based and has not been tested in human infants. The findings are preliminary and should not be used to change infant feeding practices. All infant feeding decisions should be made in consultation with a pediatrician or healthcare provider. This article is for educational purposes only and is not a substitute for professional medical advice. If you have questions about your baby’s digestion or nutrition, please consult your healthcare provider.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.