A Parent’s Guide to Infant Gut Health

How to help baby build up a robust, healthy microbiome.

Adults know, at least intuitively, that a healthy gut matters. We’ve all experienced gastrointestinal issues of one kind or another, and clearly eating well helps keep everything in working order. Science backs this up: A slew of recent studies reveal that a healthy gut — officially known as your microbiome — has wide-ranging impacts from obesity to longevity, allergies, and even heart health.

So that’s good to know about your gut, but what about your child’s? While adults’ microbiomes are made up of more than 1,000 different species of bacteria and other microbiota and over 100 trillion microorganisms, an infant’s microbiome contains less than 100 species, according to the University of Utah Genetic Science Learning Center. The way those species diversify and combine as a baby develops plays an important role in your child’s physical and cognitive future. Here’s what the latest science says about babies and gut health.

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What Is a Microbiome?

“Everyone has millions of microorganisms — bacteria, yeast, and viruses — in and on their bodies which make up their microbiome,” explain Beth Pinkos, MS, in the division of pediatric gastroenterology, nutrition, and liver diseases at Hasbro Children’s Hospital in Providence, Rhode Island. “A healthy microbiome has a balance of ‘good’ and ‘bad’ bacteria. The good bacteria work together to support a baby’s health by protecting the body, strengthening the immune system, assisting with digestion of nutrients, and helping the infant gut mature.”

Where It Begins

Many of the microbiota in an infant’s gut can be traced to Mom: Studies show that babies pick up bacteria when they pass through the birthing canal that then becomes some of the earliest inhabitants of their microbiome. During the first year of life, 30 percent of babies’ gut bacteria come from breast milk, while another 10 percent come from bacteria on the mother’s breast that the infant comes in contact with during nursing, according to a recent study in JAMA Pediatrics.

Is Breast Milk Better?

Naturally, this raises questions about how the microbiomes of C-section babies and formula-fed infants develop, something scientists are still trying to understand. “Current knowledge does not indicate that formula-fed infants have a significantly inferior health outlook based on their microbiome,” says Pinkos. “But these children may not be getting the same protective benefits of breastfed infants for many reasons.” That being said, some research suggests that prebiotic, probiotic, and synbiotic fortified formulas may have some benefit for a healthier microbiome. The short of it? “Additional research is needed,” says Pinkos. 

Foods That Improve Gut Health

When your baby is ready for solids, the best choice parents can make for first foods is to provide a variety of nutritious options from all food groups including fruits, vegetables, dairy, and whole wheat which naturally contain pre- and probiotics. Yogurt (especially with added probiotics), kefir, and other fermented food products are also healthy first choices. “Limit intake of processed foods and high-sugar foods and avoid yogurts that are loaded with processed sugar (unsweetened is best) since it raises the level of harmful bacteria in the gut,” says Pinkos, as do products with high amounts of sulfites — chemicals used in many food dyes and preservatives.

Choose whole foods with high fiber contents, including starchy vegetables, dark leafy greens, and fruits (leave the skin on when possible). Fiber has been shown to cultivate healthy gut bacteria. How much does your child need? Once they are comfortably eating whole foods, the American Academy of Pediatrics recommends taking their age, and adding five to that number to get the daily minimum total in grams of fiber.

Healthier Guts, Fewer Problems

The correlation between the microbes in your baby’s gut and their overall health is indisputable. “In early life, the microbes babies inherit, along with those that populate their microbiome, appear to play a key role in shaping physiological and immune development, hence this period of life seems to be key in determining risk for disease later in life,” says researcher Susan Lynch, Ph.D., a professor of medicine at the University of California San Francisco. Scientists at the Children’s Hospital of Pennsylvania conclude that gut bacteria also helps create about 95 percent of a child’s serotonin, which influences mood, depression, and behavior. Some of these microbes also help the body produce important vitamins and aid with digestion. And in lab studies, scientists at the University of Michigan have found that healthy gut bacteria trumps strong immune systems when it comes to helping kids fight off infections.

The Asthma Connection

In addition, a healthy microbiome can reduce your baby’s risk of developing asthma. In one of Dr. Lynch’s studies, researchers found that by one month of age, babies had three distinct gut microbiota compositions, one of which was associated with a high-risk of developing allergies by age 2, and asthma by age 4. “Those at high-risk for these conditions fail to diversify their gut microbiota,” says Dr. Lynch. 

Building Blocks for Personality?

It’s more than just straight health that is influenced by the right mix of microbes. Researchers at Ohio State University found that mood, curiosity, sociability, impulsivity, and — in boys — extroversion were also linked to more genetically diverse bacterial species. And in lab studies at McMaster University in Canada, scientists discovered that by injecting one mouse with bacteria from the microbiome of another, the first mouse began to take on similar personality characteristics.

Intelligence and Bacteria

In a first-of-its-kind study, researchers at the University of North Carolina found that infants with an optimal mix of gut microbiota at age one went on to have better cognitive skills by age two. In the study, published this January in the journal Biological Psychiatry, scientists reported “This is the first study to show that variation in the human gut microbiome is associated with cognition in typically developing infants. We have shown that microbial composition of the human gut at 1 year of age predicts cognitive performance at 2 years of age, particularly in the area of communicative behavior.” The findings could reveal important clues for kids with developmental disorders characterized by cognitive or language delay.

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