Liquid gold 

When Meghan Azad, a professor of paediatrics at the University of Manitoba, began looking for research funding to study breast milk about ten years ago, reviewers were dismissive. “There is nothing magical about breast milk,” one told her, so why study it?

For a long time the accepted wisdom was that breast milk just offered nourishment to babies. It had some fats, proteins and carbohydrates—the usual things found in food—and that was that. As a result, as biologist Katie Hinde observed in 2016, breast milk has been the subject of fewer research papers than either tomatoes or wine. A lot fewer. Have a look at this chart.

This neglect comes close to negligence. It has become clear over the years that breast milk does a lot more for babies than simply fatten them up. It shapes their immune systems, including the gut microbiome (the collection of bacteria residing in the gut that are heavily involved in keeping humans healthy). Some of the molecules in it act as decoys for viruses and harmful bacteria, preventing them from infecting infants’ cells. Breast milk also contains a variety of live cells from the mother, including stem cells—which, scientists think, could be making their way into babies’ brains and helping with early neurodevelopment. (How would they get there? Through the nose: when babies breastfeed, some of the milk ends up in their nasal cavity.)

Now scientists are starting to wonder whether some of the medicinal magic of breast milk could be harnessed to give benefits to people of all ages. As I report in this week’s science section, some components of breast milk are currently being tested in clinical trials for patients with cancer, irritable bowel syndrome and compromised immune systems. Tests in mice suggest therapeutic potential for heart disease and arthritis as well.

New ingredients of breast milk are being discovered all the time. As their importance for babies becomes clear, there is a corresponding rush to add them to baby formula. That, as my colleague Emilie Steinmark reports, requires working out how to make them, as well as how to manufacture them cheaply and at scale. It is not an easy task, but formula manufacturers and biotech firms around the world are coming up with innovative ways—from plants engineered to make sugars to protein-secreting mammary cells—to make a variety of molecules previously unique to human milk. As these manufacturing techniques improve, it will also become ever easier to conduct large-scale clinical trials of the benefits of specific breast milk components.

I stumbled on this story when looking more broadly at the research on breastfeeding. It grabbed my attention because, as one expert put it, we now go searching the bottoms of the oceans for new molecules to turn into the next miracle drug. In fact, they may have been under our noses all along.

Elsewhere in The Economist:

• How encrypted messaging apps conquered the world
• Three reasons why Britain’s submarines are in trouble

Thanks for reading. Do you have any questions or thoughts about the miracles of breast milk? Reach out to us at sciencenewsletter@economist.com. We read every email.

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