Perla Lewis-Truong’s due date was March 1. But the day after Thanksgiving, she was admitted to the hospital with severe preeclampsia, a disorder marked by a rapid rise in blood pressure that puts a mother’s health and pregnancy at risk. A week later doctors had to deliver her daughter by cesarean section, 13 weeks early. Baby Celia weighed only a pound and a half. After two months, she is four pounds and still nearly translucent but healthy, lying in a small heated pod in the Children’s Hospital of the University of California, Davis, in Sacramento. Celia was lucky to be born here, at a teaching hospital with an advanced neonatal intensive care unit. Premature babies face many potential problems, including necrotizing enterocolitis, in which intestinal walls deteriorate and bacteria invade. A quarter of infants with the disease die, and survivors may suffer neurological problems for years.
Mark Underwood, a neonatologist at U.C. Davis, is constantly seeking better treatments for his delicate patients. Contrary to traditional practice, his focus is not on drugs but on diet. Underwood believes that many cases of necrotizing enterocolitis could be prevented by giving preemies a special daily cocktail of probiotics (healthy bacteria) and prebiotics (the food those bacteria eat), all inspired by what might be considered the ultimate superfood: human milk.
“Milk is powerful as a preventer of disease and an enhancer of performance,” says Bruce German, a food chemist at U.C. Davis. “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.
Consider baby Celia’s situation at Davis. It is an impressive hospital, but even the best neonatal intensive care unit presents a challenging environment for a preemie. Fetuses are bacterially naive, with little exposure to pathogens or other microbes before birth. Then they get exposed in a very specific way: first through the birth canal, a wellspring of bacteria, and then through near-constant snuggling with their moms—ideally accompanied by immediate breast-feeding. Within days, microbes both good and bad start to colonize the baby and help educate the immune system. But Celia, born through a C-section and then placed in an isolette, acquired most of her bacteria not from her mother but from a hospital. Too young to breast-feed, she received nourishment, including liquid vitamins and a few drops of her mother’s milk, through a catheter in her umbilical cord.
“We think that makes them sick,” says Underwood, a soft-spoken man in glasses and a blue polo shirt. For preemies, infections come fast and furious, but those who receive breast milk are half as likely to suffer from necrotizing enterocolitis as their formula-fed peers. Such statistics are driving Underwood and his colleagues to peer deeper into human milk. And their findings are poised to improve health not just for babies, but for all of us.
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 food researcher Bruce German from his office in the new, light-dappled Robert Mondavi Institute for Wine and Food Science on the Davis campus.
Bode’s lab has shown that the same family of compounds ably attach to a protozoan parasite and potentially lethal pathogen, Entamoeba histolytica. Bode believes these sugars, because they are indigestible, journey intact to the colon, where their structure mimics molecules on the surface of gut epithelial cells. When the parasite tries to hook onto the intestinal wall, it latches onto the milk decoy instead. The milk molecules then most likely flush the parasite out. Bode’s finding could have big implications for both child and adult health, because E. histolytica is the world’s third-leading cause of death by parasites. These particular oligosaccharides would be expensive to synthesize in a lab, but simpler sugars derived from cow’s milk also appear to work well against E. histolytica.
Bode points to human-milk oligosaccharides performing other heroic medical feats. They inhibit Streptococcus pneumoniae, the bacterium frequently responsible for respiratory and ear infections, which may explain why breast-fed infants get fewer respiratory illnesses than formula-fed ones. And at Boston College, biochemist David Newburg and his colleagues have found that another oligosaccharide called 2′-fucosyllactose is effective at warding off Campylobacter, cholera, and enteropathogenic E. coli—a frequent cause of diarrhea—in animal models. He believes it has the same impact in humans.
Cocktails of milk-derived compounds could soon start moving from the lab to medical use. Newburg has cofounded Glycosyn, Inc. to test his oligosaccharide in humans within two years. The company makes 2′-fucosyllactose from yeast and bacteria and is working toward marketing a nutritional supplement for children in the developing world, where diarrheal diseases kill more than a million of them a year. Especially at risk are newborns and weaning toddlers, who lose the protection of mother’s milk at the same time they are exposed to a wider variety of food pathogens. Newburg and his collaborators are also studying a human-milk fat that seems to inhibit HIB from infecting human cells, and yet another milk component that prevents hiv from disabling the host’s immune cells.
The big infant formula producers are closely watching these promising breast milk studies. Abbott, Mead Johnson, the British company Aptamil, and the German company HiPP have begun offering formula with a prebiotic called GOS, for galacto-oligosaccharide, derived from cow’s-milk lactose. At least two companies have started supplementing formula with probiotics. HiPP uses a strain of human-milk Lactobacillus to help ward off infections. And Nestlé’s Gerber has introduced an infant formula with bifidobacteria to support infants’ immune systems. “There’s a whole lot happening,” Newburg says. “The formula companies are all partnering up to get a supply, get prepared, and do big human testing.”
New milk-inspired therapies may soon find their way into the intensive care unit, too. Back at U.C. Davis, Mark Underwood is working on his next project, developing lipids from human milk to bathe and protect preemie skin. Bruce German responds with characteristic enthusiasm. “It’s better than Vaseline!”