Human milk

The impressive power of breast milk

Breast-feeding boosts an infant’s immune system 
and promotes a healthy gut. Scientists are 
finally isolating the compounds responsible. The result 
could be a health breakthrough for all ages.

“Milk is powerful as a preventer of disease and an enhancer of 
performance,” says Bruce German, a food chemist at UC Davis, California. “By understanding how it does what it does, we can bring the principles, the mechanisms of action, and the benefits to everyone.”

Human milk’s most important role could be preventing infant disease and boosting immunity by cultivating a balance of microbes in the gut and the rest of the body, a kind of internal ecosystem called the microbiome. In fact, many researchers now believe that mammalian lactation originally evolved as a protective, not a nutritional, adaptation.

For a substance so important to the success of our species, human milk has, until recently, been largely neglected by researchers. For one thing, most infants in the developed world can now survive without it. Doctors and scientists long assumed most of its value was nutritional, in which case it could be replaced by commercial infant formula, which is now a $3.5 billion-a-year business in the United States alone.

Far more money has gone into improving efficiencies in the dairy industry or studying the cholesterol-reducing effects of red wine than into understanding human breast milk.

“People should not underestimate how important the money is,” says German from his office in the new, light-dappled Robert Mondavi Institute for Wine and Food Science on the Davis campus.

German had his lightbulb moment in 1994, when he decided that food scientists were “overblowing the red wine thing.” He asked himself, what is the one food that’s clearly meant to help humans? German answers his own question effusively: “Milk!”

German took a sabbatical in Switzerland to work at food giant Nestlé, one of the world’s leading sellers of infant formula. Where better to learn about human milk, he reasoned, than at a company so keen to mimic it?

Nestlé researchers suspected that milk could “grab onto pathogens,” flushing them out of the baby, and even act as an anti-inflammatory, calming hypervigilant, immature immune cells. But like other researchers, they didn’t know the mechanism involved. If only the means of action could be decoded, and the healthy components isolated, identified, and produced in quantity, German thought, then they could be repurposed to treat everything from diarrheal diseases to cancer to HIV.

One class of substances in particular intrigued German: oligosaccharides. These sugar molecules, among the most common solid components of milk, are not digestible. Since we cannot metabolize them, he wondered, why are they there in such abundance? He had a hunch that the answer might be related to the human microbiome.

If the molecules are not feeding us, he reasoned, maybe they are feeding the microbes that boost our health. On his return to Davis, German began collaborating with molecular biologists and chemists to isolate the oligosaccharides and test them against various bacteria…..

Discover Magazine: Read the full story