8.1: Nutrition during Infancy

Breastmilk and breast feeding

Newborn infants receive all their nutrition from breastmilk or formula. The demand and supply of breastmilk is a positive feedback loop – the more the infant sucks on the breast, the more milk is produced. Therefore at the start, there is often very little supply of actual milk and in breastfed infants, regular sucking in the first week (or pumping/expressing breastmilk) is essential for setting up the breasts to produce milk. Cow’s milk is too fatty for human infants to digest but infant formula is a viable alternative. However, many culture wars have erupted over whether infants are better off being breastfed or bottle fed, though the American Association of Pediatrics suggests that it supports the unequivocal evidence that breast milk buffers infants against a variety of diseases and conditions (AAP, 2021).

At the start of this discussion we need to differentiate between breast milk and breast feeding, as well as formula and bottle feeding. Of course the source of breast milk is the human breast, and if the infant is being breastfed, they are likely getting breast milk. However, it is entirely possible for parents to express/pump breast milk and feed the infant using a bottle. In fact, I have two family members who did exactly that for up to eight months after their babies were born. The point of drawing this distinction is that there are many confounding variables here. Those who claim that breastfeeding is better because breast milk is more nutritious, less allergenic, better for babies’ immune systems, and easier for babies to digest, and serve health benefits for the lactating individual are correct in claiming these facts about breast milk, but whether it comes directly from a breast or is pumped into a bottle and then fed to baby shouldn’t be at issue. On the other hand, breastfeeding might be better because it leads to greater jaw and tooth development for baby than regular artificial nipples (orthodontic ones can overcome some of those problems). Certainly, there are situations where breastmilk (and breastfeeding) needs to be ruled out if the lactating individual has an illness that might be passed down in breastmilk, is taking medication that might be passed on, or is taking other drugs or alcohol. In such cases, or if for other personal or health reasons breastfeeding and breastmilk are not an option, formula is a very reasonable and healthy alternative.

Solid foods

Humans are the only primates where caregivers supplement breastfeeding with solid foods, and have multiple children at different developmental stages to feed and take care of. Most of the world's health authorities recommend that infants not be fed solids before 4 or 6 months, but worldwide studies done before 2010 indicate that many parents feed their infants solids even as early as 4 weeks of age. However especially in the last decade there has been greater emphasis on advising breastfeeding and that might have influenced the rate and timing of early solid food introduction (Borowitz, 2021).

The flavor of what pregnant and lactating individuals eat is recognized and preferred by infants (and even as late as eight years of age). There also seems to be a sensitive period for acceptance of different flavors and tastes. Infants who taste bitter before four months of age are more likely to continue to accept bitter foods even at five years of age, and are more willing to try and to accept other varied flavors later in development. Infants who are exposed to different food textures also do better than those who are not (Borowitz, 2021).

It has been suggested that if infants are fed solids too early they are more likely to develop allergies. However, studies have shown that early exposure (at 4 months) to cow's milk, wheat, peanut, cooked egg, sesame and whitefish were less likely to be allergic to one or more food at 3 years than those who were exclusively breastfed until 6 months (Borowitz, 2021).

There is also no association between early introduction to solids and increased risk of obesity later in childhood. Borowitz (2021) concludes that as long as there is uncontaminated water and adequate nutrition available, it is not a problem to introduce solids into an infant's diet at any age.

References:

American Association of Pediatrics (March 2021). Breastfeeding Overview.

Borowitz S. M. (2021). First Bites-Why, When, and What Solid Foods to Feed Infants. Frontiers in pediatrics, 9, 654171. https://doi.org/10.3389/fped.2021.654171