Breast milk, even offered partially alongside formula feeding, changes the chemical makeup鈥攐r metabolome鈥攐f an infant鈥檚 gut in ways that positively influence brain development and may boost test scores years later, suggests new CU 麻豆影院 research.
鈥淔or those听who struggle with exclusively breastfeeding, this study suggests your baby can still get significant benefits if you breastfeed as much as you can,鈥� said senior author Tanya Alderete, an assistant professor of integrative physiology at CU 麻豆影院.
The study, published Dec. 13 in the also identifies specific metabolites that manufacturers may want to consider adding to infant formula to optimize healthy brain development and concerning compounds they should try to leave out.
鈥淥ur research suggests that even at low levels, some contaminants found in formula may have negative neurodevelopmental effects downstream,鈥� said first author Bridget Chalifour, a postdoctoral researcher in Alderete鈥檚 lab.
Tanya Alderete
A health report card for the gut
For the study, the research team examined what is known as the 鈥渇ecal metabolome鈥濃�攖he diverse collection of metabolites found in the gut and shed in poop. Metabolites are small molecules that are churned out by gut bacteria as a byproduct of metabolizing food and make their way into the bloodstream, impacting the brain and other organs.
Breast milk, formula and solid food also contain metabolites.
While scientists have long studied our resident bacteria, or microbiome, to better understand human health, the emerging field of 鈥渕etabolomics鈥� goes a step further.
鈥淟ooking at the gut microbiome tells us which bacteria are there, while looking at the fecal metabolome can help tell us what they are doing,鈥� said Chalifour. 鈥淚t鈥檚 like a health report card for the gut.鈥�
The team collected fecal samples from 112 infants at 1听and 6 months old and worked with Donghai Liang, assistant professor of environmental health at Emory University in Atlanta, and other colleagues to chemically analyze which metabolites were present. They grouped infants based on how much breast milk versus听formula they were given.听At age 2, the children took cognitive, motor and language tests.
The study found that the samples from infants in different feeding groups contained significantly different levels of metabolites.
For instance, at 1 month old, 17 metabolites were more abundant the more breast milk a baby had, and 40 were more abundant the more formula a baby had.
When looking more closely at specific metabolites, the researchers identified 14 that were also associated with differences in test scores at age 2.
With only one notable exception, caffeine, the more metabolites associated with breast milk a baby had in their stool, the better they did on cognitive tests as toddlers (more on caffeine later).
The more metabolites associated with formula feeding they had, the worse听they did.
鈥淭he consistency of these results is striking and supports the benefits of breastfeeding as much as possible in early life,鈥� said Alderete.
Some metabolites associated with听formula concerning
One particularly beneficial metabolite was cholesterol: At both 1 and 6 months old, the more breast milk a baby had, the more cholesterol they had in their stool. And the more cholesterol babies had in their stool, the better they did on cognitive tests. This makes sense, as the fatty acid is critical for forming healthy circuits between brain cells. As the authors note, 80% to 90% of the brain鈥檚 volume grows in the first two years of life.
In contrast, the more a baby was formula fed, the higher their levels of a metabolite called cadaverine, a known contaminant formed via fermentation.
In the study, the more a child was formula-fed, the higher their levels of cadaverine and the lower their test scores at age 2. While the compound is considered a toxin at higher levels, the Food and Drug Administration permits low levels in infant formula.
鈥淚t may be that formula manufacturers should be more vigilant in getting levels of this compound down to zero,鈥� said Chalifour.
Interestingly, babies who consumed breast milk had higher levels of caffeine in their stool鈥攑erhaps because moms may have been expressing milk or breastfeeding听over a cup of coffee.
Not surprisingly, higher levels of caffeine, a stimulant, were associated with poorer cognitive scores. Prenatal caffeine exposure has previously been associated with lower neurodevelopmental scores, and experts recommend , or a cup and a half, of coffee per day for pregnant women.
Not all or nothing
The World Health Organization recommends that infants be exclusively breastfed for the first six months of life, but in the United States, only 63% of infants are exclusively breastfed immediately following birth. By six months, only a quarter of U.S. babies are exclusively breastfed.
Alderete acknowledges that, for some parents, breastfeeding听isn't possible. She hopes her research can ultimately help manufacturers improve formula to make it as close to breast milk as it can be. And听she stresses that just because a child was not breastfed does not mean they鈥檒l have neurodevelopmental deficits. Early feeding patterns are just one of many factors that contribute to how a brain develops.
Her takeaway to new parents having trouble breastfeeding exclusively: Don鈥檛 give up. It doesn鈥檛 have to be all or nothing.
鈥淛ust increasing the proportion of breast milk relative to formula may have a positive impact on your developing child,鈥� she said.
