Why brain food might start with your kid’s gut health

Scientists are taking a closer look at the connection between diet and a child’s gut microbiome—and how that might influence brain function.

We all know the vitamins, minerals, and fiber provided by fresh fruits, vegetables and grains are important for growing young bodies and brains. But scientists are looking more closely at how kids’ diets influence their gut health—and how that might affect everything from mood to mental health to cognitive development.

Just like an adult’s gut, a child’s digestive tract is naturally populated by dozens of types of beneficial bacteria, also known as the gut microbiome. These serve a variety of functions, including regulating immune function and metabolism.

Diet can play a huge role in the health of a person’s gut microbiome. One job of our gut bacteria is to transform the foods we eat into chemicals and compounds—including feel-good neurotransmitters like serotonin and dopamine—that pass into the bloodstream for direct delivery to the brain. The brain also sends signals to the digestive system that influence its environment and function, which in turn may affect the activity of our resident bacteria. This two-way channel of communication is called the gut-brain axis.

Too much of certain foods can cause an explosion of harmful bacteria involved in inflammation, depression, obesity, and diabetes (a process called dysbiosis). Sugar, for example, has been implicated in gut biome disruptions that impair memory in rats.

But the converse is also true. Fiber, for instance, seems to be extremely important for bacteria strains considered healthy and supportive of human health. And according to Dorottya Nagy-Szakal, chief medical officer at Biotia, researchers are focusing on connections between our gut bacteria and how they might be involved in fatigue, depression, and even cognitive behavior.

“With a healthy diet, you can push back on microbiota imbalances,” says Nagy-Szakal, who studied the gut-brain axis as part of her post-doctoral work at Columbia University “Healthy bacteria thrive on healthy food.”

Although gut health is far less studied in children, more and more studies are revealing connections between gut health in childhood and health later in life. Here’s what scientists have discovered so far—and some ideas on how parents can feed the fire for a healthy gut.

The science behind gut health and kids 

Kids aren’t just tiny adults when it comes to the composition of the gut microbiome. For instance, infants’ microbiomes are less diverse overall than older children; the transition to solid foods shifts the gut microbiome from milk-oriented digesters to a more diverse collection that can use fuel from solid foods. But the length of time a child spends in each stage of gut development—duration of breastfeeding, for instance—may influence how their bodies’ immune systems develop, and even the development of their cognitive skills, based in part on the composition and activity of their gut bacteria.

Some of the early research in humans seems to point toward developmental “windows” of opportunity for gut health—in other words, set periods during childhood where being exposed to certain communities of bacteria and their products seem to be particularly important for healthy immune systems and brain development.

Sharon Donovan, who studies the connection between the gut microbiome and diet in young children at the University of Illinois, says that establishing a healthy microbiome early in life is critical but warns “there’s still a lot we don’t know.”

Although research points to a connection between cognitive benefits and a “healthy” microbiome in kids, exactly what a healthy mix of bacteria looks like is still somewhat of a mystery. It can differ vastly between person to person, as well. Most of the current research on the connection between healthy guts and a well-performing brain are by association only: Certain groups of bacteria tend to pop up again and again in studies looking at measures of cognition and overall mental function.

“It could be that the microbiome is promoting cognitive development, or it could be that kids with higher cognitive potential are interacting with their environment in a way that changes how their microbiome grows,” says Rebecca Knickmeyer, associate professor of pediatrics and human development at Michigan State University. “The relationships are there—but maybe there’s something else out there we didn’t look at that would explain these relationships.”

Brain food for your gut

Still, Donovan notes that the evidence clearly shows the gut microbiota do affect how we utilize nutrients—as well as how our brains work. “And if you want to provide beneficial bacteria,” she adds, “they need something to live on—a healthy diet.”

Gut-healthy foods aren’t always on a kid’s must-have menu. Donovan advises that parents help by modeling healthy eating habits and exploring new foods together with their kids. Here are some ideas to get started.

Gut goodness: Fiber (aka veggies!)

Why it matters: Vegetables top the list for gut-healthy foods. The secret ingredient? Fiber, says immunologist Megan Meyer, senior director of science communications with the International Food Information Council. Dietary fibers help gut microbiota produce short-chain fatty acids that are thought to play an important role in the chemical “crosstalk” between the brain and the gut. Additionally, fiber supports a diverse community of “good” bacteria that can crowd out “bad” bacteria associated with inflammation, infections, and other ailments.

How to get kids eating: Something as simple as pairing veggies with a dip can entice a kid to try a less-desirable green vegetable. Meyer also suggests adding veggies to something your child already loves, like green beans or peas to your kid’s favorite mac-and-cheese. But if they absolutely won’t touch the green stuff, fruits like blackberries, pears, and apples (with the peel!); whole grains like oatmeal and popcorn; and nuts like pistachios and almonds are also good sources of beneficial fiber.

Gut goodness: Fermented stuff

Why it matters: Fermented foods are a rich source of beneficial microbes that can help support gut health. In adults, regular consumption of these foods rich in lactic acid bacteria have been associated with improved digestion, cholesterol control, and reduced infections. Though most brain-gut bacteria studies have been conducted in rodents, at least one human study showed that consuming fermented dairy products affected regions of the brain involved in processing emotion and sensation.

How to get kids eating: Tart kombucha and pungent sauerkraut might not go over well with kids, but lots of kid-friendly fermented options exist. Low-sugar yogurts and kefirs are fan favorites, and Ethiopian injera bread, made from fermented teff, is delightfully floppy. Parents can also try using tofu, salty miso, and chewy tempeh as the base for many recipes.

Gut goodness: Prebiotic-rich foods

Why it matters: While the jury is still out on whether probiotic supplements are definitively helpful for kids, Donovan says they’re definitely not harmful. The problem is that if the right bacteria from certain foods aren’t already in the gut, the probiotic strains in commercial products might just pass on through. It’s better, she suggests, to consume prebiotics—compounds in the food we eat that provide the proper fuel for probiotics to do their good work.

Meyer says inulin is a common prebiotic added to some prepared foods, but whole-food winners rich in prebiotics include artichokes, asparagus, bananas, garlic, onions, oats, barley, wheat, and legumes.

How to get kids eating: Keep a diversity of fruits, vegetables, whole-grain foods on hand at all times, to encourage sampling and exploration by kids, Donovan suggests. Nagy-Szakal emphasizes that the less processed a food is, the better.

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