Parents generally think of bacteria as something to avoid. But your baby’s gut (his stomach and intestines) is naturally home to millions of bacteria—and that’s a reason to be grateful. Healthy bodies depend on having a bacteria-rich microbiome to function properly.

As awareness of the gut microbiome has grown in the past decade or so, the potential health benefits of consuming extra “good bacteria” have also increased. Here’s a look at the latest research you’ll want to know for your baby.

Good Bacteria: What They Are

Good bacteria already exist naturally in the body. The main substances used to influence gut health and promote good bacteria are probiotics and prebiotics.

Probiotics are supplements or enhanced foods that contain living microorganisms. These so-called “friendly” bacteria can change the bacteria balance in the body. Example: yogurt with lactobacillus.

Prebiotics are supplements or foods that contain an ingredient that can’t be digested normally. These stimulate the growth of friendly bacteria, acting as food for the bacteria. Examples of prebiotics: Compounds like oligosaccharides that are found in human breast milk or infant formula and toddler milk.

Synbiotics are created when probiotics and prebiotics are combined.

Potential Benefits of Good Bacteria

A summary report in the journal Pediatrics in 2010 found that randomized clinical trials show probiotics are somewhat effective in supporting gastrointestinal wellness in healthy children.

Promising, but still preliminary, research has found probiotics may help ease childhood gastrointestinal issues and colic. For example, an Italian study reported in JAMA Pediatrics in 2014 that babies fed a probiotic supplement from birth emptied their bowels more, had less spit-up, and had less colicky crying at 3 months than those on a placebo.

Prebiotics also may help support skin health in otherwise healthy babies, according to the Pediatrics report. The jury is still out on whether either prebiotics or probiotics have an effect on allergies.