It would be eight long weeks before King returned home. On strong antibiotics and hormone replacement therapy, she couldn’t safely breastfeed her twins. “It was almost more traumatic than what I had been through in the hospital,” says King, whose older son self-weaned at the age of 3. “Because I had breastfed my son for so long, I knew the nutritional benefits breast milk provides.”According to the World Health Organization, breast milk is an important source of nutrients and energy for infants, protecting against gastrointestinal infections, and helping to reduce obesity risk while improving IQ later on in life, among other benefits. For mothers like King—unable to breastfeed yet still wanting to provide their babies human milk—the options are limited. Milk banks aren’t available in every country or city, and marketplaces on Facebook, Craigslist, and other online platforms are poorly regulated.
They remained a staple of life in the region through the Bronze Age and into the Iron Age. At first, some archaeologists suggested that the spouted vessels might have been used to feed sick or disabled adults—and there was no way to be certain that the vessels (even the cute animal-shaped ones) were for infants.
Fengru Lin is trying to find a way around the problem. In January 2019, Lin founded TurtleTree Labs, a Singapore-based startup that is attempting to grow human breast milk in a laboratory. The company starts with stem cells taken from donor breast milk, multiplies them before putting them into a growth fluid within a hollow fiber bioreactor—“imagine a giant steel cup with hundreds and thousands of little perforated straws,” says Lin. There, the cells differentiate into mammary ones and start producing milk. The entire process takes three weeks, says Lin, and the mammary cells can lactate for roughly 200 days.
It’s a technique that can theoretically be used to obtain milk from any mammal, as long as stem cells are available. TurtleTree has already successfully produced full-composition cow’s milk from stem cells in freshly expressed cow's milk. It now plans to do the same for human milk. “We’re not trying to replace breastfeeding, which is something we’re fully behind," says Lin, who was first drawn to the idea of making milk from cells because of a passion for cheesemaking.
More than 80 percent of new mothers in the US and UK start out breastfeeding, but only half and a third, respectively, still do so exclusively at six months. Globally, this figure is 37 percent. The reasons vary: Some struggle to produce sufficient amounts, while others have to return to work where pumping and storing milk isn’t convenient. Many also find expressing milk physically painful, experiencing mastitis, chafed nipples, and other excruciating effects. Then there are mothers on medications or undergoing treatments that make it unsafe for them to breastfeed. And sometimes, babies may be premature or too weak to suckle. “The fact is, mothers rely on infant formula,” says Lin. “That’s where we want to be the next best thing.”
While formula has come a long way, especially in the past two decades, it still lacks many nutrients found in breast milk. And that’s largely because most infant formulas are based on cow, rather than human, milk. “The two contain mostly the same type of molecules but in different proportions,” says Alan Kelly, a food scientist at University College Cork in Ireland. “And the difference in those levels is very physiologically significant.”