Breast milk is a near-perfect food that’s custom-suited to the needs of the baby it’s feeding. Infant formula misses that quality mark, and while scientists have made strides to reduce the differences between breast milk and formula, health gaps still exist. For example, some (but not all) studies show that formula-fed babies have higher risks of obesity and diabetes than their breastfed counterparts.

One reason why formula can’t quite catch up to breast milk is because human milk is complex, containing more than 1,600 distinct proteins, some of which evolve the longer they stay in the mammary glands. By contrast, bovine milk—the primary ingredient in most infant formulas—has far fewer distinct proteins.

One very young startup in San Francisco is attempting to close those health gaps through bioengineering. Launched this past February, BioNascent is replacing the bovine proteins in formula with lab-grown human proteins made by inserting human genes into yeast and fungi. The company says it has already replicated alpha-lactalbumin, a protein that makes up between 20 and 30 percent of the total protein content in breast milk but only about 3 percent of the proteins in bovine milk.

Alpha-lactalbumin is a proof-of-concept protein chosen for its molecular simplicity, says BioNascent CEO and chief scientific officer Craig Rouskey, a molecular biologist who has worked in recombinant protein technology for 15 years. In 2014, Rouskey launched Real Vegan Cheese, a separate project that’s using a similar approach to create cow-free cheese by replacing bovine proteins with identical ones grown in a lab.

For BioNascent, Rouskey is using alpha-lactalbumin to prove that human proteins can also be lab-grown in hopes of attracting enough commercial investment to help the fledgling company get through the costly FDA approval process. If BioNascent’s replicant protein passes, “it would be the first human recombinant protein approved by the FDA as a food ingredient,” says Rouskey. “A lot of people who have tried this in the past went to the FDA with their data and the FDA said no.”

An FDA spokesperson did not comment on whether BioNascent’s protein would be the first replicant human protein approved as a food ingredient. Human recombinant proteins have been approved for medicinal uses and are currently an ingredient in some pharmaceuticals.

To get FDA approval, Rouskey will need to prove that his proteins are exact copies of the ones produced by the body, and that the body welcomes them without a fight. BioNascent will also need evidence, which as of yet does not exist, from other researchers that consuming human recombinant protein is safe.

The company has selected 14 proteins it believes are key to closing some significant health gaps and will start working its way down the list. It hopes to produce its second protein in the next two months.

J. Bruce German, a food chemist at the University of California, Davis, whose research focuses on milk, says that replacing bovine proteins could have positive health impacts but to what extent is unclear.

“In principle, the more human proteins in formula the better,” German says, adding that since little is known about what exactly gives breast milk better health outcomes, it’s extremely difficult to predict the impact of changing a handful of proteins. If BioNascent could produce a formula that incorporated human proteins in the amounts typical for a breast milk at a certain stage in a child’s development, “that would constitute a big change from what infant formula is today,” he says.

Still, swapping proteins won’t put formula in the same league as mother’s milk, German says, in part because the latter is customized to the individual baby, varies from mom to mom, and changes according to the baby’s evolving needs. If a baby gets sick, for example, mothers can produce breast milk with customized antibodies to fight that specific infection.

“However cleverly engineered, yeast will never be a good mammary gland,” German says. “If I was in the business of making leather-coated steering wheels, no one would say I was making Ferraris.”

Rouskey doesn’t believe that bioengineered formula will match breast milk, but believes that it will bring formula one step closer. For now, he’s focused on scoring enough funding to give the idea a shot.

“Those are our two main goals,” he says. “Stay alive and produce our next round of proteins.”