When strolling along the health store aisles, you might see the words ‘probiotics’ and ‘prebiotics’ winking at you. While a vague ‘good for you’ feeling might awaken at their sight, what do they mean exactly? How to consume these trendy buzzwords smartly? And where did our obsession with them begin?

“There are roughly as many microbial cells living in and on our body as human cells, and this mass of microbes is commonly referred to as the human microbiome,” says Matthew Olm, Microbiology Ph.D. candidate in Banfield Lab, UC Berkeley. “The highest density of these bacteria is located in our gut, where they can affect human health for better or worse. Good bacteria help us break down food, train our immune systems, and prevent bad bacteria from making us sick.” And it matters: “Thanks to new scientific methods, we've found that sick people often have different looking microbiomes than healthy people,” says Olm. “For example, imbalances in the gut microbiome have been associated with obesity, inflammatory bowel diseases, fatty liver disease, and numerous additional disorders.”

According to Olm, consuming prebiotics and probiotics encourages the growth of a healthy microbiome; prebiotics are specific food compounds that we humans can't digest, but good bacteria need in order to grow, while probiotics are actual living good bacteria you can eat in the hopes of them taking residence in your gut. In other words, to maintain a healthy gut microbiome it’s essential to feed the probiotics (aka bacteria) with prebiotics through foods we consume in our diet.

When looking for prebiotics, in addition to supplements and manufactured products the keyword, says Olm, is fiber. “Ithas consistently been associated with a "good" microbiome,” he says. Fiber can be found in fruits, vegetables, grains, nuts and other earth-linked foods. “Hunter-gatherer cultures eat orders of magnitude more fiber than we do in America and Europe, and as a result have much more diverse and healthy-looking microbiomes,” Olm concludes. Mystery (partially) solved.

To nurture a happy, healthy gut and promote overall wellness, try including the following prebiotic foods in your diet:

Chicory Root

A member of the dandelion family, chicory root is particularly rich in bacteria friendly inulin, a complex carbohydrate that’s a great source of fiber. The plant is commonly utilized as a caffeine-free alternative to coffee; I was hooked after trying chicory root coffee at the famous Cafe Du Monde in New Orleans!

Garlic

Garlic is just as nutritious as it is delicious. Not only does this bulbous plant have an amazing ability to spice up just about any dish, studies suggest garlic also has a long list of health benefits. Though garlic is often praised for its powerful antioxidant activity and ability to enhance immune cell functioning, it’s also a great source of Fructooligosaccharides (FOS)—a relatively small carbohydrate that’s a well-documented prebiotic. Try mincing raw garlic and adding it to your favorite avocado toast!

Oats and Barley

Oats and barley are two of the top sources of β-glucan, a complex carbohydrate that is well known for its ability to increase cardiovascular health by lowering LDL (bad) cholesterol levels; they also happen to be some of your gut bacteria’s favorite foods! Before heading to school or work in the morning, get your pre- and probiotic fix by mixing apples, whole fat (plain) yogurt, and a dash of honey in your oatmeal!

Milk

Though many people are lactose intolerant, if you have the ability to drink milk—research supports your decision! Whole milk is a great source of protein, fats, carbohydrates, vitamins, minerals, and galacto-oligosaccharide (GOS), a well known prebiotic. Choose organic milk whenever possible; studies show that milk from grass-fed, organically raised cows have a higher ratio of heart-healthy polyunsaturated fatty acids (PUFAs) when compared to conventional milk.

Flora Tsapovsky is a food, style and culture writer splitting her time between San Francisco and Tel Aviv. She contributes to the San Francisco Chronicle, Afar, Bon Appetit and more. She is the founder of Bicoastalista, a women's website dedicated to bi-coastal living, travel, and style from a wide cultural lens. She teaches journalism and creative writing in the Bay Area.