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Biotechnology to Create Infant Formula Closely Matching Human Breast Milk

Breast milk is still the best milk for babies, especially for the first six months after birth. In line with this, the American Academy of Pediatrics (AAP) recommends that infants be fed with breast milk, exclusively for the first six months of life, after which breast milk should continue until the baby’s first birthday, or longer, as complementary foods are introduced. Breast milk is healthy, whether taken directly from the breast, or as pumped milk from a bottle. The option to pump can make breastfeeding a little more convenient for some women in certain situations, but for others breastfeeding may be impractical for a variety of reasons, even with pumping. Moreover, a large fraction of mothers are unable to produce enough milk, even when their schedules would otherwise permit them to nurse. Consequently, roughly 75 percent of babies in the United States receive at least some formula by six months of age, plus there are many who are formula fed partly, or completely from the time of birth. And yet, now the US is in the midst of a massive shortage of baby formula, with specialists looking ahead to a future in which not only will more formula be available to meet the growing needs, but a future in which infant formula is much more similar to human milk than it is today.

Dating back to the 19th century, but really developing on an industrial level during the 20th century, infant formula comes as a powder that you mix with water. The formula contains various nutrients and other substances. These include the macronutrients: protein, carbohydrates, and fats. Most baby formula uses protein derived from cow milk, which is something that infants absolutely cannot have, at least for the first six months, but the protein is modified substantially, so that it differs from that of cow milk. To begin, cow milk has a lot more protein than human milk contains, so going back to the earliest infant formula developed and mass produced many decades ago, the powder is formulated so that when mixed with the prescribed amount of water, the concentration of protein will be similar to that of human breast milk. Whereas cow milk has a lot of casein protein and less whey protein, human milk has a higher ratio of whey versus casein. Thus, most infant formulas use more whey than casein from the cow milk. All infant formula whose protein comes from cow milk has the protein broken into pieces. In some infant formulas, the protein is completely hydrolyzed, meaning broken down into its individual amino acid building blocks. Therefore, the baby’s immune system will not treat it as cow milk protein. Babies who are particularly sensitive need hydrolyzed protein formula. This is true even when the source of protein is not cow milk, but soy, a plant product. The problem with using soy has always been that babies can have sensitivities or allergies to soy, just as they can have them to cow protein.

Infant formula also contains fats, which typically are from vegetable oils. As for the carbohydrates, they come from many different sources, most of them derived from plants, but the most common infant formulas for babies without digestive problems contain lactose (milk sugar) among the carbohydrates. Lactose comes from cow milk, but that doesn’t matter because it’s only the protein component of cow milk that can have particular biological effects that are dangerous.

Despite numerous advances and efforts over the decades to make infant formula similar to human milk, the older techniques still create a product somewhere intermediate between human milk and non-human milk. But this is where biotechnology has come on the scene during the current century.

Back in 2011, researchers in China demonstrated that they could employ genetic engineering to create cows that made partly humanized milk. They did this by transferring a gene for a human protein that is secreted in breast milk into the genome of cow embryos. This is a protein that helps breastfed infants resist infection, but the milk from genetically modified cows back then was like cow milk in terms of its other nutrients. A few years later, however, researchers demonstrated that they could genetically engineer cow milk with a more human kind of protein mix. Efforts are progressing to extend the techniques to affect also the non-protein components of milk. It’s rather complicated and will take some more years.

Meanwhile, an American company based in North Carolina is advancing on another biotechnology front. This one is a cellular agriculture strategy, meaning similar to the process of created the lab grown meat. Rather than employing cow muscle stem cells to produce beef, however, the company uses cultured cells descended from cells of human breast tissue. Specifically, these are the cells that produce breast milk in women, when stimulated appropriately with the various hormones, beginning at the end of pregnancy. Therefore, shortage of infant formula or not, it looks as though, in the years to come, we’ll see advances in biotechnology, not only supply additional infant formula to meet growing needs, but also to produce formula that matches the milk supplied from lactating women.

David Warmflash
Dr. David Warmflash is a science communicator and physician with a research background in astrobiology and space medicine. He has completed research fellowships at NASA Johnson Space Center, the University of Pennsylvania, and Brandeis University. Since 2002, he has been collaborating with The Planetary Society on experiments helping us to understand the effects of deep space radiation on life forms, and since 2011 has worked nearly full time in medical writing and science journalism. His focus area includes the emergence of new biotechnologies and their impact on biomedicine, public health, and society.

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