Biomilq and the New Science of Artificial Breast Milk

The biotech industry takes on infant nutrition.

March 6, 2023

New ventures in the world’s oldest food reflect our era’s enthusiasm for tech-based solutions to perennial human problems.Illustration by Bianca Bagnarelli

Not long ago, I suited up in a white coat and safety goggles and entered a quiet laboratory where an experiment at the frontiers of science and parenthood was under way. A young engineer with a tidy beard escorted me past rows of benches to a large freezer. He opened it to reveal an array of ice-caked steel drawers and, wearing blue Cryo-Gloves (reverse oven mitts, essentially), removed a small bottle from the chill, which measured minus eighty degrees Celsius. At the bottom of the bottle, two hundred and fifty millilitres of liquid had formed a shallow, colorless puck.

I was visiting Biomilq, a startup, founded by Leila Strickland and Michelle Egger, that is working to produce lab-grown breast milk. Biomilq’s headquarters are in North Carolina’s Research Triangle Park, a seven-thousand-acre wedge of pine forests and office complexes between Durham, Chapel Hill, and Raleigh. The bottle creaked as it began to adjust to the room’s warmth, and the engineer hastened to put it back in the freezer.

You could call the bottle’s contents Biomilq, or maybe just milk, or, as the engineer did—indicating a number of smaller bottles also stowed in the freezer—“our best shots to date.” The frozen puck represented a week and a half’s worth of output from a single line of lab-cultured human mammary cells. The company hopes to use these cells and others like them to re-create as closely as possible the process of making human milk. About three years before my visit, in February of 2020, Biomilq announced that it had successfully used cells to produce lactose and casein, a sugar and a protein found in breast milk. “Our opinion as a company—and most of us internally, too—is that breast-feeding, at the breast, has benefits that no one will ever be able to mimic,” Egger, a food scientist turned entrepreneur, told me. “If you can breast-feed—do it. Great. But the reality is, a majority of parents cannot exclusively breast-feed. . . . And that’s not for lack of trying.”

Breast milk is often described as a kind of elixir—“perfect nutrition,” in the words of a 2015 paper in Early Human Development. The health benefits that have been attributed to breast milk include protection against asthma, diabetes, diarrhea, ear infections, eczema, obesity, and sudden infant death syndrome. Some much cited research also credits breast milk with producing smarter children, although this is difficult to substantiate. Tabulating a complete science-backed list of the advantages of breast milk over infant formula can be a challenge. The available data are limited by a lack of structural support for breast-feeding. There are, for example, statistical concerns about comparing parents who can’t undertake the time-intensive process of breast-feeding with those who can. (Studies tend to show that parents who breast-feed are more educated and affluent than parents who don’t, and thus confer other benefits on their children.) Regardless of the precise details of breast milk’s advantages, it remains the widely acknowledged gold standard in infant nutrition; to replicate it in a laboratory would be alchemy. On a neon sign in Biomilq’s office, the words “Making Magic” hang beneath the curve of a decorously abstract lactating breast.

In a conference room labelled “Skim,” I met with Strickland, a mother of two with cropped wavy hair and a soft lisp. On one wall was a series of photographs, by Sophie Harris-Taylor, that depict nursing mothers in various states of domestic weariness and serenity. The photos were among the first things that Egger bought for Biomilq’s workspace—a purchase in keeping with the company’s efforts to build a mom-forward brand. At the heart of those efforts is Strickland’s own experience with breast-feeding. Fourteen years ago, Strickland, then a postdoctoral fellow in cell biology at Stanford, became pregnant. At the time, she lived near Santa Cruz, a beach town in Northern California where a particular goddess-mama vibe around maternity prevailed. “Culturally, there was a lot of promotion of, like, ‘You want to do a natural birth, you don’t want an epidural,’ ” she told me. “You know, ‘Your body is made for this.’ ” To some extent, Strickland embraced that attitude. She certainly planned to breast-feed. But the first weeks of her baby’s life called those expectations into question. “When you find, actually, my body is not making enough milk for my baby—what’s up with that?” she said. “Is my body actually not made for this?”

Strickland began to think of her struggle, a not uncommon one, as a scientific challenge. Then, in 2013, a tissue engineer named Mark Post unveiled a hamburger made from lab-grown beef. Produced at a cost of some three hundred and twenty-five thousand dollars, it tasted, in Post’s words, “reasonably good,” and helped to kick off a period of burgeoning interest among investors in “cellular agriculture,” an area of biotechnology devoted to finding lab-grown alternatives to conventional agricultural products. Startups were using engineered yeast to generate animal proteins, or were culturing animal cells directly. Strickland and her husband, a software developer, were excited about the possibilities. What if there were a way to generate breast milk from cells in a lab? They had moved to North Carolina a few years earlier, and Strickland started to experiment using tissue from a cow udder and secondhand lab equipment. In 2019, a mutual friend introduced Strickland to Egger, a Duke M.B.A. student focussed on social entrepreneurship. (Strickland and her husband are now separated. They are currently litigating disputes over the product and its name, ownership, genesis, and technology. He continues to operate an L.L.C. that they formed together, 108Labs, through which he is pursuing lab-grown milk products on his own.)

Egger has a sign in her office that reads “Wake me when I’m CEO.” She spent her early career at General Mills, where she helped develop such products as Lärabar, Go-Gurt, and low-sugar bulk yogurt for schools. While training as a food scientist, Egger had planned to avoid working on dairy—she has hyperosmia, a heightened sense of smell, and the world of bovine odors was uninviting—but the field’s complexity drew her in. “Dairy research is a little bit of art and science combined,” she told me. “Often we do things not because we know why it works but because we just know that it does.” Egger became Biomilq’s C.E.O.

In 2020, the company received $3.5 million in funding in a round led by Breakthrough Energy Ventures, an investment firm founded by Bill Gates. Biomilq’s early days were shaped by the pandemic. This came with difficulties—the company’s lab manager recalls trading with neighboring startups for gloves and pipettes during supply-chain shortages—but also unexpected benefits. Strickland and Egger would hear “Sesame Street” in the background during calls with investors and know that they were talking to working parents. In 2021, they closed a twenty-one-million-dollar series-A funding round. Then, in 2022, a national formula shortage brought urgent attention to the matter of how babies get fed. It was an opening for a company like Biomilq to promote an alternative—and the opening arrived in an era of enthusiasm for tech-based solutions to the fundamental problems of human life. If fertility and longevity were subject to biotech intervention, why not infant nutrition, too?

The process of making breast milk in a human body begins during pregnancy, when hormonal changes prompt mammary cells to multiply. After delivery, two of the pregnancy hormones—estrogen and progesterone—drop off, while prolactin remains. This spurs the mammary cells to draw carbohydrates, amino acids, and fatty acids from the mother’s bloodstream, and to convert these raw materials into the macronutrients required to feed a baby. In Biomilq’s case, the mammary cells come from milk and breast-tissue samples provided by donors, and the cells multiply in vitro under the care of a team of scientists tasked with keeping them “happy.” The cells are then moved to a hollow-fibre bioreactor—a large tube filled with hundreds of tiny porous tubes that are covered in a layer of the lab-grown cells. As nutrients flow through the small tubes, the cells secrete milk components into the large tube, where they collect.

Describing the results as “milk components,” not “milk,” is a crucial distinction. Biomilq has demonstrated that its technology can produce many of the macronutrients found in milk, including proteins, complex carbohydrates, and bioactive lipids, but it cannot yet create them in the same ratios and quantities necessary to approximate breast milk. Other elements of breast milk are beyond the scope of the company’s ambition. A mother’s antibodies, for example, are present in her milk, but they aren’t produced by the mammary cells, and, because Biomilq’s product will come from a sterile lab environment, it won’t offer any kind of beneficial gut bacteria.

Then there’s breast milk’s characteristic variability—the way its chemical composition changes over the course of months, days, even a single feed—and its ability to respond (through the mechanism of infant backwash, some suggest) to the nutritional needs of a particular baby. Whatever Biomilq winds up being, it will have to be uniform, and “that is not breast milk,” Strickland said. But she still believes in the power of what’s produced by the human mammary cell. Bovine milk and human milk may have some of the same proteins, but there are “species-specific differences in how those proteins are processed,” she said. “We believe that these components will be more bioactive, more absorbable, and interact better with the gut of the infant.”

Katherine Richeson, who oversees product development at Biomilq, is a cell biologist who conducted research on cancer therapies, including breast-cancer treatment, prior to coming to the company. She was struck by the dearth of research on mammary cells in relation to lactation. “Reading the literature didn’t take that long,” she told me. Bruce German, a chemist and food-science professor at the University of California, Davis, is a leading researcher on the subject of human milk. His work has shown how even indigestible parts of breast milk help to nourish bacteria that improve infants’ gut health. (German has also provided unpaid advice to Biomilq.) He sees the historic lack of academic interest in lactation as the result of prioritizing the concerns of “middle-aged white men” over those of mothers and infants. “There are more papers on wine than there are on milk,” he said.

Biomilq’s methods and equipment are drawn from the world of biopharmaceutical technology, and using them to create a commercially viable food product will require working on a radically different scale. “It’s a two-pronged challenge,” Strickland said. “We want to make orders of magnitude more stuff than what the technology is designed for today, and we want to sell that stuff orders of magnitude cheaper.” When asked about the company’s target consumer, Strickland said that it would be a “worst-case scenario” for her if Biomilq replicated the inequalities that already plague infant feeding. “I won’t consider it a success until it’s fully accessible,” she told me. Egger took a somewhat more pragmatic stance: the company was aiming to one day be priced “at the top end” of infant formula, and would likely be more expensive than that at the beginning. “While accessibility is first and foremost for us, it’s not going to be accessible to every person in the world immediately,” Egger said. For now, the company is making a pitch to customers who are already sold on the value of breast-feeding but are frustrated by its challenges, and who are willing to pay to get their child the next best thing.

The relative value of the next best thing is an open question. “What we care about is not just the best nutritional start in life—we’re looking for the best start in life,” Laurence Grummer-Strawn, who works at the World Health Organization and specializes in infant and early-childhood nutrition, told me. The “best start” offered by breast-feeding encompasses all the things impossible to incorporate into a cell-cultured product—breast milk’s fine-tuned changeability, the parent-child bonding. Without those, “we’re talking about essentially a better formula,” Grummer-Strawn went on. “But frankly, from a nutritional perspective, infant formula is not that bad.” He saw the focus on minute chemical improvements as part of a broader American tendency to prioritize breast milk, the substance, over breast-feeding, the act.

I was thirty-one weeks pregnant when I visited Biomilq’s headquarters, and by then I’d heard friends’ stories of their own labor-intensive efforts to generate human milk. For people embarking on parenthood in 2023, breast-feeding is a recommendation right up there with “Read to your child” and “Don’t smoke.” A large number of American parents start out doing so—83.2 per cent of infants born in 2019 were breast-fed at least briefly, according to the C.D.C. But by six months—the age through which the American Academy of Pediatrics recommends that babies consume only breast milk—24.9 per cent were exclusively breast-fed, and only 55.8 per cent were receiving breast milk at all. “It’s pretty incontrovertible that breast-feeding is optimal nutrition for the baby,” Olena Dobczansky, a nurse and lactation consultant who oversees the breast-feeding program at Manhattan’s Lenox Hill Hospital, told me. It’s just that families leave hospitals like hers and confront a reality that makes the A.A.P. guidelines sound fantastical. “A fourth of American mothers go back to work two weeks after having a baby,” Dobczansky said. At that point postpartum, she noted, “you’re still bleeding.” Paid maternity leave—which, among high-income countries, only the U.S. does not mandate—translates to higher rates of breast-feeding.

Even for parents lucky enough to receive generous paid leave, it takes practice, and often the help of someone with experience, to get a baby properly latched and nursing. The journey from there may involve frightening uncertainty (is the baby getting enough to eat?) and physical discomfort (sore nipples, mastitis), and requires time—breast-feeding is, especially in the beginning, a constant occupation. Pumping necessitates its own choreography. Women I know became fluent in paraphernalia with names ranging from puns (the My Brest Friend nursing pillow) to euphemisms (the Simple Wishes hands-free pumping bra). Some presided over their own frosty vaults: pumping then stockpiling in dedicated freezers, and fretting over power outages during storms. Milk, I was learning, didn’t have to be the result of biotech innovation to seem faintly experimental and very precious.

The story of breast-feeding in America could start with Cotton Mather, who admonished Puritan women to nurse their babies rather than become “one of the careless women, living at ease”—a call to health and hard work which has never quite abated where motherhood is concerned. But who breast-feeds and why has been defined by the same forces that shape life in America more broadly. In the antebellum South, for example, Black women were made to nurse white babies at the expense of their own. Nearly two hundred years later, Black women’s breast-feeding rates lag behind those of other demographic groups, one of many health disparities—along with a stark maternal-mortality rate—that form part of the ongoing legacy of slavery.

“It’s as fraught as abortion,” Jacqueline Wolf, an emeritus historian of medicine at Ohio University and the author of a history of breast-feeding and formula in the U.S., aptly titled “Don’t Kill Your Baby,” told me. “There’s almost nothing that raises more social issues than infant feeding.” Wolf dates the emergence of what became known as “the feeding question” to the eighteen-seventies, when mothers across the country began raising concerns about their milk supply. “The big change that was sparked by urbanization and industrialization was suddenly having to pay attention to a mechanical clock,” she said. Earlier infant-care manuals had advised feeding a baby when he showed signs of hunger. Now medical advice put infants on feeding schedules as rigid as railway timetables. But, as Wolf pointed out, “to build up a milk supply, you need to put the baby to the breast often, especially in the first few months.” The women complaining that they lacked sufficient milk were not, as one theory had it, suffering from the ill effects of too much education during puberty. Rather, they were following advice unwittingly engineered to fail. The contours of the American conversation around breast-feeding were thus established: expert authority counselled one thing, practical reality dictated another, and mothers who found themselves caught in between were often regarded as the source of the problem.

One miracle solution of the late nineteenth century came from a new feature of urban life: milk laboratories, which provided some in the middle class with access to “percentage feeding.” A doctor would study a baby’s stool and arrive at a precise mathematical formula (hence “formula”) for her diet. A milk-laboratory chemist would tweak cow’s milk accordingly. The dominant school of thought in early-twentieth-century child-rearing valued scientific rigor over intuition and tradition; kissing your baby excessively, much less nursing her, came to seem suspect. Even so, some authorities endorsed the medical value of breast-feeding. In 1937, Ladies’ Home Journal published an article headlined “Babies Should Be Breast-fed,” written by Dr. Herman N. Bundesen, the president of the Chicago Board of Health. Bundesen used public-health statistics to make his case: “Out of every ten babies who die in the first year of life, eight are bottle fed—not breast fed.” (Don’t kill your baby!)

Yet imperatives like Bundesen’s rarely translated into meaningful support for women interested in breast-feeding, as Jessica Martucci, a historian of medicine at the University of Pennsylvania and the author of “Back to the Breast,” a study of breast-feeding’s postwar resurgence, has argued. By the nineteen-forties, most mothers were giving birth in hospitals, where orderly routine—babies in nurseries, bottles on schedules—often took priority over the personal attention required to initiate breast-feeding. Sometimes the discouragement was still more direct: into the sixties, some hospitals treated maternity patients with hormonal “dry-up pills.”

Under these circumstances, mothers who wished to breast-feed were often obliged to figure it out for themselves. Niles Polk Rumely Newton, a Columbia-trained psychologist who wrote a popular mid-century child-rearing book, breast-fed her children with help from her mother, but she was troubled by the lack of official guidance. With her obstetrician husband, she devised a series of experiments based on research performed on cows, and she used herself as a test subject. Newton helped to establish the workings of the human “let down” reflex, a hormonal process that prompts the release of milk in response to a baby’s suckling. Basically, a mother had to be able to relax. (A beer could help, the Newtons suggested.) “In the dairy business,” a 1955 Ladies’ Home Journal article on the Newtons noted, “the farmer’s loss can be measured in dollars and cents; perhaps for this reason, far more research has been concentrated on lactation in cows than in humans.”