Why breast milk is the best

Scientists have discovered why breast milk is better than infant formula.

Illinois: Scientists at the University of Illinois have discovered why breast milk is better than infant formula.

"For the first time, we can see that breast milk induces genetic pathways that are quite different from those in formula-fed infants. Although formula makers have tried to develop a product that’s as much like breast milk as possible, hundreds of genes were expressed differently in the breast-fed and formula-fed groups," said Sharon Donovan, a U of I professor of nutrition.

Although both breast-fed and formula-fed babies gain weight and seem to develop similarly, scientists have known for a long time that breast milk contains immune-protective components that make a breast-fed infant’s risk lower for all kinds of illnesses, she said.

"The intestinal tract of the newborn undergoes marked changes in response to feeding. And the response to human milk exceeds that of formula, suggesting that the bioactive components in breast milk are important in this response. What we haven’t known is how breast milk protects the infant and particularly how it regulates the development of the intestine," she said.

Understanding those differences should help formula makers develop a product that is more like the real thing, she said. The scientists hope to develop a signature gene or group of genes to use as a biomarker for breast-fed infants.

Many of the differences found by the scientists were in fundamental genes that regulate the development of the intestine and provide immune defence for the infant.

In the study, Donovan used a new technique to examine intestinal gene expression in 22 healthy infants—12 breast-fed, 10 formula-fed.

The technique involved isolating intestinal cells shed in the infants’ stools, then comparing the expression of different genes between the two groups. Mothers in the study collected fecal samples from their babies at one, two, and three months of age. Scientists were then able to isolate high-quality genetic material, focusing on the RNA to get a gene expression or signature.
Donovan said that intestinal cells turn over completely every three days as billions of cells are made, perform their function, and are exfoliated. Examining the shed cells is a non-invasive way to examine intestinal health and see how nutrition affects intestinal development in infants.

Understanding early intestinal development is important for many reasons, she said.
The study will appear in the June 2010 issue of the American Journal of Physiology, Gastrointestinal and Liver Physiology.


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