Probiotics, Prebiotics, Postbiotics: A Guide to What Your Gut Really Needs

Your gut is an ecosystem.

Inside it, trillions of microorganisms are at work breaking down food, supporting immune function, communicating with your brain, and helping maintain the integrity of your gut lining. 

Like any ecosystem, this internal one depends on balance and support. It needs the right organisms, the right nourishment, and the right conditions to thrive. 

When that balance is disrupted—often by stress, illness, antibiotics, poor sleep, or a processed diet lacking in nutrients—you may notice bloating, constipation, diarrhea, food sensitivities, and other digestive changes.

It doesn’t stop within your digestive system, either. Much like the smallest parts of an ecosystem can affect what happens at the broadest level, your gut bacteria’s influence extends to your immune system, your brain and mental health, your skin, your general inflammation levels, and more. 

A big part of maintaining this balance is prioritizing the three “biotics”: probiotics, prebiotics, and postbiotics.

Probiotics: The Live Microbes

“Probiotics—which you’re likely most familiar with—are live, beneficial microorganisms (bacteria and yeasts) that typically work by reducing inflammation, supporting the gut barrier, regulating immune activity, limiting harmful microbes, and creating a healthier environment for beneficial bacteria to thrive,” says Sarah Bird, functional nurse practitioner at PALM Health. 

They may also help restore gut function after disruptions such as antibiotics, infection, illness, stress, or major dietary changes.

The best way to encourage diverse and flourishing flora in the gut is to get your probiotics through food. You can find probiotics in certain fermented foods, including:

• Yogurt with live cultures
• Kefir
• Sauerkraut
• Kimchi
• Miso
• Tempeh
• Fermented vegetables

You can also find probiotics in supplement form.

The catch, however, is that probiotic supplements are strain-specific. “Taking one probiotic supplement for a long period of time will give you the benefit of that particular strain, but it will not support diversity in the microbial community—there are trillions of different strains needed for a flourishing microbiome,” says Sarah. 

Diversity is just as important in probiotics as quantity. The more diverse the microbiome, the more resilient the gut—and a diet rich in various probiotic foods can help boost that diversity.

Prebiotics: Food for the Microbes

Prebiotics are like precursors to probiotics: they are fibers and compounds that feed the beneficial bacteria in your gut. Your body can’t fully digest these fibers, but your gut bacteria can through fermentation. As they ferment them, they produce compounds that support your gut lining, immune signaling, and inflammation balance.

Prebiotic-rich foods include:

• Garlic
• Onions
• Leeks
• Asparagus
• Oats
• Beans
• Lentils
• Chickpeas
• Apples
• Slightly green bananas
• Flaxseeds
• Chia seeds
• Cooked and cooled potatoes or rice
• Root vegetables (radishes, beets, yams, yucca are Sarah’s favorites)

Prioritizing probiotics is great, but you also need to feed them properly. The goal here is, again, diversity and variety: your gut microbes thrive on different fibers, different plants, and different colors on your plate.

Postbiotics: The Beneficial Byproducts

Postbiotics aren’t something you consume or take in, necessarily, but they help explain the importance of prioritizing probiotics and prebiotics.

Postbiotics are the beneficial compounds or microbial components created through microbial activity. In simpler terms, they’re some of the helpful “byproducts” your gut microbes produce.

One example is butyrate, a short-chain fatty acid made when gut bacteria ferment certain fibers. Butyrate helps fuel cells in the colon and plays a role in gut barrier strength.

When you populate your gut microbiome well and feed it well, it will produce these postbiotics that benefit your overall health downstream.

The Bottom Line: Nourish the Whole Ecosystem

Probiotics are what you may hear most about, but they aren’t the whole story. “Cultivating a healthy gut starts by fostering the right environment for your microbiome to do what it was designed to do,” says Sarah.

So start with the basics: eat a variety of plant-rich foods, include fermented foods if you tolerate them, prioritize fiber, hydrate well, and keep in mind the factors that can throw off your gut balance: stress, poor sleep, infections, antibiotics, and other chronic illnesses. 

If you’re concerned about something that may be disrupting your microbiome, a functional medicine practitioner can help you find the root cause and create a more personalized plan to re-establish balance.

Remember, your gut is not a simple, independent organ, it’s an ecosystem—and it’s key to treat it as such.