How can scientists make infant formula more like human milk?
Closing the gap between formulas and breast milk.
There are many reasons why a new parent might choose to feed a baby infant formula — either exclusively or as a supplement to human milk. Indeed, there are now a huge number of infant formulas on display at grocery stores. The formulas are sold as powders and are reconstituted with water before use. The infant nutrition market is expected to expand to more than $92 billion globally by 2023.
The requirements for formulas are set by the Codex Alimentarius, a joint food program between the Food and Agriculture Organization of the UN and the WHO. Whilst the formulas are sold in a seemingly endless variety of formulations, the majority contain the same basic components to ensure infants get enough nutrition. Codex lists more than 30 nutritional ingredients but the three major constituents are fat (4.4–6.0 g per 100 kcal), proteins (1.8–3.0 g per 100 kcal), and carbohydrates (9.0–14.0 g per 100 kcal). The most common formulas are going to have vegetable oils as the sources of fat, lactose as the carbohydrate source, milk protein with whey and casein as the most common proteins. The formulas also need supplements of vitamins and minerals. Babies need a secondary source of vitamin D along with other cofactors and electrolytes. Infants also need iron (0.15 — 3.0 mg of iron per 100 kcal) in their diet as their iron stores run out within a few weeks of birth.
Infant formula is still a long way from recreating the composition of human-produced milk, which also contains growth hormones, immunological factors, and other compounds to help an infant thrive. Human milk includes a parent’s microbes and antibodies, which change over the course of an infant’s life. It is thus probably impossible to make a formula that fully recapitulates all the qualities of human milk.
One way manufacturers are trying to close the gap between breast milk and formula, is by including docosahexaenoic acid (DHA) and arachidonic acid (ARA). These long-chain polyunsaturated fatty acids are crucial for brain development in the first year of life and are also associated with increased visual acuity. Babies can also make their own DHA from linoleic acid which is explicitly required in all formulas.
Formulas often advertise the presence of human milk oligosaccharides (HMO). These are complex carbohydrates that act as prebiotics in human milk by promoting healthy bacterial communities in the guts of infants. There are actually more than 200 known HMOs but the most common one in formulas is trisaccharide 2′-fucosyllactose (2′-FL). The next step in making formulas more similar to human milk is to include complex sugars which more accurately represent HMO.
