I used to buy a couple of brands of baby food and switch them back and forth. They usually forgot something.
It's a whole science. Some things are essential, some are fancy additives.
https://cen.acs.org/food/food-ingredien ... mpaign=CENInfant formula is designed as a complete substitute for human milk to meet the full nutritional needs of babies under 12 months of age. Internationally, the required components for formulas are set by the Codex Alimentarius, a joint food standards program overseen by the Food and Agriculture Organization of the United Nations and WHO. Individual countries can also set additional guidelines.
In total, the codex lists more than 30 required nutritional ingredients for infant formula, including vitamins and minerals, but the three major constituents are fats, proteins, and carbohydrates—the primary building blocks that little humans need to grow and develop. “The most common formulas are going to be cow’s milk protein—with whey and casein as the most common proteins,” Sobik says. “Then they’ll have vegetable oils as the fat source and lactose as the carbohydrate source.”
The codex specifies that formulas should have 1.8–3.0 g of protein, 4.4–6.0 g of fat, and 9.0–14.0 g of carbohydrates (specifically lactose or glucose) per 100 kcal, a typical infant-sized serving of formula. The US Food and Drug Administration has similar recommendations.
In addition to the principal building blocks that compose their diet, infants need supplements of vitamins and minerals. Even babies fed human milk need a secondary source of vitamin D, which is a required nutrient in infant formulas, along with other cofactors and electrolytes.
Of those micronutrients, Sobik says, iron is one of the most important. Because their iron stores will run out within a few weeks of birth, infants need a supplement in their diet. In the US, the FDA requires that all formulas are fortified with between 0.15 and 3.0 mg of iron per 100 kcal, a range recommended by the American Academy of Pediatrics (Pediatrics 1999, DOI: 10.1542/peds.104.1.119). The codex sets the iron minimum at 0.45 mg per 100 kcal.
Another additive that some brands also advertise is human milk oligosaccharide (HMO). Steven Townsend, an organic chemist at Vanderbilt University, led a team that showed that these complex carbohydrates act as prebiotics in human milk by promoting healthy bacterial communities in the guts of infants, which may contribute to a stronger immune system (ACS Infect. Dis. 2017, DOI: 10.1021/acsinfecdis.7b00183). Human milk has these different sugar molecules at concentrations that vary according to a number of factors, including a parent’s genetics and the infant’s age.