Food for Thought

In a lab at the University of New South Wales, in Australia, scientist Margaret Morris is giving her rats a memory test. She sets them in their usual box. But she has rearranged the objects in the box. Some rats sniff them curiously. Others just move on. They don’t remember the objects were once in a different place.

The rats with sharper memory were fed a steady diet of low-fat, healthy chow. The rats that gorged × gorge SW PRODUCTIONS/GETTY IMAGES to consume in large amounts (verb) At the slumber party, we gorged on popcorn and candy. for two weeks on junk food—such as cake, meat pies, chips, and cookies—were forgetful.

Food can have the same effect on people. “If you’re eating junk food regularly, and not eating enough fruit and veggies,” Morris told TIME for Kids, “the changes in your gut may be affecting brain function.” Changes in the gut can affect a person’s overall health, too.

Gut Check

Scientists have long known the brain communicates with the stomach and intestines to control digestion. Recently, they have found that the gut talks back. It may even tell the brain what to do.

The gut’s power comes from the bacteria living inside it. This community of microbes × microbe HERO IMAGES/GETTY IMAGES an extremely small living thing that can be seen only with a microscope (noun) The researcher examined microbes using a microscope. is called the microbiome × microbiome KATERYNA KON/SCIENCE PHOTO LIBRARY—GETTY IMAGES a community of microorganisms that live in certain environment, such as the human body (noun) Many different types of bacteria live in the microbiome inside your intestines. . It helps the digestive system break down food. In the process, it sends signals through the body and to the brain. Which message the brain receives depends on which kinds of microbes are living in the gut.

Most salty and sugary foods wipe out the bacteria that protect you from illness and keep your mind sharp. A microbiome lacking the right bacteria can lead to disorders like obesity and depression.

Rob Knight is a scientist at the University of California, San Diego. More than 10,000 people around the world have sent him poop samples. The samples tell Knight about the bacteria living in people’s bellies and which ones may be associated with disease.

SMART FOOD Look for yogurt with live cultures. It can keep your gut healthy.

Knight recommends eating yogurt. It is packed with healthy bacteria. Does that mean no French fries? “Having them sometimes is okay,” Knight says. “It’s the long-term habits that really matter. Being good to your microbiome over the next six months is a lot more important than what you ate yesterday, or what you eat tomorrow.”

Stop & Think! Why does the author cite studies by scientists? Do these studies add credibility to the story? Why or why not?