There is simply no better food for an infant than a mother’s breast milk. The body is truly amazing; it creates and produces breast milk to support a growing and developing baby, and it’s why breast milk has often been called nature’s perfect first food. When you think about it, breast milk is an evolutionary guarantee that our offspring will survive—and thrive—long term, which is why the health benefits of breastfeeding are extensive.

Breastfeeding exclusively for at least one full year, which is the critical time frame when the cells of the body and brain are becoming established, has been shown to have significant benefits on a child’s physical and mental health, advantages that carry well into adulthood. This is why one of the first questions that I ask a new patient is whether she or he was breastfed as an infant.

Numerous studies show that children who are breastfed exclusively are less prone—throughout their lives—to obesity, allergies, eczema, diabetes, asthma, respiratory illnesses, ear infections, and digestive problems, as well as being at less risk of developing autoimmune diseases like type 1 diabetes and multiple sclerosis. Breastfeeding for at least one year has also been linked to better mental health, including less depression and stress-related and behavioral issues—through age fourteen, though I would argue that this benefit extends into adulthood.

The question is, why does breastmilk have such a powerful effect on health? Yes, breast milk has a rich balance of healthy nutrients for a rapidly developing infant including lactose or milk sugars, protein, and fat. But breast milk’s effects on health has more to do with its impact on early formation of the gut, which has been found in recent years to benefit the body and brain long term. 

The Gut: Where Health Begins

The gut is where our health begins, and it’s immediately after birth that the gut begins to form into anenterotype—a scientific name for an ecosystem—which is conserved for the rest of our lives. In fact, this early shaping of the gut, which includes the formation of critical health-promoting bacterial species, can only happen in infancy and early childhood. Research has shown, that after the age of three—despite any attempts to change this—we simply cannot recreate these same bacterial colonies, which include a core of more than nine bacterial types including StaphylococcusStreptococcusLactobacillus, Bacteroides, and Bifidobacterium.

We can change the numbers of bacteria in the gut through the use of probiotics, but we cannot affect these initial colonies of bacteria. This can only be established in infancy—which is why breast milk is absolutely critical for the lifetime health of the gut. 

• A healthy gut stimulates a strong immune system. The right balance of bacteria in the gut stimulates the healthy development of our immune system. The bacterial colonies found in breast milk, along with something called oligosaccharides, or HMOs, that act as prebiotics to feed gut bacteria and antimicrobials to inhibit the growth of harmful bacteria, are the primary stimulus for the development of our immunity.

According to the American Academy of Pediatrics, breast milk is also rich in antibodies like IgA, which help to prevent infections and other illnesses by blocking pathogens from attaching to the gut. This explains why breastfed infants are less likely to develop health problems like ear and respiratory infections as infants and later on as adolescents and adults.

• A healthy gut is key to balanced brain health. As the gut develops, so too does the brain. Breast milk is a rich source of essential fatty acids, which are critical for healthy neurological development, and hormones like leptin that seem to have a stress-reducing effect on an infant’s behavior, according to one study in The Journal of Pediatrics.

We also know that the gut communicates with every part of the body, including the nervous system and the brain through something called the gut-brain axis. This means that when the gut is balanced, it sends signals up to the brain allowing for optimal neural development and circuitry. This can result in a calmer overall mood, as well as better regulate her/his neurological behavior.

What to Do If You Can’t Breastfeed?

I understand that sometimes breastfeeding isn’t possible. While the benefits of breastfeeding can’t be completely transferred to formula feeding, it is possible to mitigate some of the effects of not breastfeeding by doing these things:

Do what and when you can. Any breast milk is better than none, so even low milk producers are doing their babies a ton of good by offering some breast milk along with formula. If you can’t physically breastfeed, the latest pumps are discrete and efficient, so it’s easier than ever to incorporate pumping breastmilk into a busy schedule. I recommend doing what you can for as long as your milk supply lasts; if possible, for at least a year.

Choose an organic formula with prebiotics, probiotics, and essential fatty acids. While formulas can’t match breast milk’s composition, the newest formulas do contain some essential components that can help feed a baby’s gut.

Bottom line: Breast milk is absolutely the best form of food for your baby, but your infant can still have a healthier gut even if you have to supplement or feed your baby formula.

Kristine Gedroic, MD, is author of A Nation of Unwell and Medical Director of the Gedroic Medical Institute in Morristown, NJ. She is Clinical Associate Professor in the Department of Medicine at Rutgers New Jersey Medical School.