probiotic, prebiotic, oh my!

feed your gut and starve your gremlins

Grace Ciaccia

Nov 17, 2025

The gut is my Roman Empire.

If the kids are still using that phrase, then yes, the gut is the thing I think about way too often. Back in 2013, I signed up for an integrative nutrition course that opened my eyes to so much, but especially to the gut and all it does.

At the time, talking about gut health was still considered pretty woo-woo, but that didn’t stop me from bringing it up whenever (and to whomever) I could. Fast forward just over a decade, and things have changed a lot. Gut health has gone from fringe to front-page. Exciting, yes but it’s also gotten… complicated.

So many supplements. So much information. So many people dispensing that information. Somewhere along the way, I made it my mission to simplify it all, to cut through the noise and help people understand their gut microbiomes in a way that’s practical, grounded, and actually doable.

A quick gut check 😉

Your gut does so much more than just digest your food. It’s home to trillions of bacteria, both good and bad, that influence everything from your immunity and energy to your mood and metabolism. Collectively, they make up your gut microbiome, a community that works best when it’s in balance and diverse.

When the good bacteria outnumber the bad, your digestion runs smoothly, inflammation stays in check, and your body feels supported. But when things get out of balance it can throw everything off, leading to bloating, fatigue, cravings, and even mood shifts.

Keeping that balance is the name of the game, and that’s where probiotics and prebiotics come in.

Probiotics vs. Prebiotics: the dynamic duo

Let’s start with the basics because while they sound similar, probiotics and prebiotics play very different roles in your gut.

Probiotics are the good bacteria — the living organisms that help keep your gut microbiome balanced. You’ll find them naturally in fermented foods like yogurt, kefir and sauerkraut.

Prebiotics, on the other hand, are the food for those bacteria. They are non-digestible fibers that help your good microbes thrive. Garlic, onions, leeks, asparagus, bananas, oats, apples, and Jerusalem artichokes, to name a few, are all prebiotic powerhouses. Without prebiotics, those good bacteria starve and can’t do their best work.

🦠 Probiotics = good bacteria🌿 Prebiotics = good bacteria’s food

The goal is to create a gut environment where those microbes can thrive naturally. It’s about consistency and variety, not extremes.

Feeding the good (and starving the bad)

Diet is one of the most powerful ways to influence your gut. Your microbes are like a massive dinner party and what you eat decides who gets fed.

The “good” bacteria thrive on fiber-rich, plant-based foods: vegetables, fruits, legumes, whole grains, nuts, and seeds. These foods act as natural prebiotics, feeding the beneficial bacteria that support digestion, lower inflammation, regulate immunity, and even influence mood and stress through the gut–brain axis.

A diverse diet of fibers helps cultivate a resilient microbiome and a happier mind. Research continues to show that a diverse gut plays a major role in overall health, from metabolic function to immune strength. (You can explore some of the research here and here.)

So, how do you build a diverse community of bacteria? You guessed it — through diversity in your diet. Aim to eat as many different plants as possible. I see recommendations as high as 30 different plants per week. I prefer not to set lofty goals to remain practical, so maybe start by adding 2 - 3 new plants a week.

Forgive the aging millennial reference, but whenever I think of feeding bad bacteria I think of the movie Gremlins. Feed them after midnight, and chaos ensues. The “bad” bacteria in your gut work kind of the same way. They love ultra-processed foods (UPF), excess sugar, and artificial additives and when you overfeed them, they multiply fast, crowding out the good guys and throwing your gut out of balance.

Every meal is a chance to feed your inner ecosystem. Choose colorful plants, fermented foods, and whole, minimally processed ingredients that keep your gut community thriving (and your mischievous microbes in check).

What is dysbiosis?

Dysbiosis is an imbalance in your gut microbiome: when the good bacteria are outnumbered by the bad, or when overall diversity drops. It can show up as:

• Loss of beneficial bacteria

• Overgrowth of potentially harmful bacteria

• Reduced diversity of gut microbes

Research links dysbiosis to multiple health conditions, including:

• Infections

• Inflammatory Bowel Disease (IBD)

• Obesity: Lower bacterial diversity, and fewer short-chain fatty acid (SCFA) producers.

• Type 2 Diabetes & metabolic disorders: Microbiome shifts and gut barrier issues.

• Colorectal Cancer: Fewer butyrate-producing bacteria and more potentially pathogenic species.

Diets high in UPFs or very high in protein or fat and low in fiber can contribute to dysbiosis. It is pretty known now that UPFs are stripped of any beneficial nutrients, so they feed the bad bacteria linked to inflammation and gut barrier dysfunction and reduce (starve) beneficial bacteria. A low-fiber diet doesn’t just affect digestion, it can also influence mood and mental well-being through the gut-brain axis. Feeding your good bacteria with fiber helps them produce short-chain fatty acids that support both gut and brain health.

So, when your gut ecosystem falls out of balance (there are too few good bugs, too many bad bugs, and low diversity) it can affect digestion, immunity, metabolism, and more. With 70-80% of immune cells living in the gut, it is no surprise that the gut plays such an important role in our immune response. You can read more about that here .

🌿 A case for a plant-forward plate

It’s worth noting again that a plant-forward diet is one of the simplest ways to support a diverse, thriving gut microbiome. And by plant-forward, I don’t mean vegan or vegetarian, just a diet rich in fruits, vegetables, legumes, nuts, and whole grains.

Research consistently shows that fiber which is found almost exclusively in plant foods, is key to feeding the good bacteria, producing beneficial compounds like short-chain fatty acids, and supporting both gut and brain health. Yet in a world obsessed with protein, this is often overlooked. Research also shows that a long-term low fiber and high fat/high protein diet destroys a significant number of species in the gut.

In a world where everyone is searching for pill, powder or potion, remember what you need is usually right on your plate. As Michael Pollan famously said: “Eat food, not too much, mostly plants.” Your gut will thank you for listening.

Keeping your gut (and your gremlins) happy

Supporting your gut doesn’t have to mean an overhaul. Small, consistent habits make the biggest difference. Think of it as daily maintenance for your microbiome:

🌈 Eat the rainbow. More plant colors = more fiber diversity = a stronger microbiome.🥣 Include fermented foods. Yogurt, kefir, sauerkraut = beneficial bacteria.

🚶‍♀️ Move daily. Walking, yoga, pilates, dancing any and all movement supports digestion and microbial balance.

💊 Be mindful with supplements. Probiotics can help, but food first. Strain specificity and lab tested supplements matters.

Your gut is a living ecosystem. Feed the good guys, starve the gremlins, and your body will thank you from the inside out.

To supplement or not to supplement

One question I get asked all the time is whether someone should take a probiotic or prebiotic supplement. My thinking: if you’re already eating at least 3 servings of fermented foods (yogurt, kefir, sauerkraut, kimchi) daily and playing in dirt (exposure to soil microbes has been linked to a more diverse gut microbiome), you likely don’t need a probiotic supplement. But for most people, that’s not the case, so a high-quality probiotic can be helpful. Since we’re learning more about the importance of a diverse gut, switching up probiotic strains every so often can also be beneficial, and as with most supplements, consistency is key.

As for prebiotics, I usually don’t recommend a supplement because they’re so readily available in whole foods such as fruits, vegetables, and complex carbs. Most people get enough through their diet. If you’re following a high-protein or high-fat diet that’s low in fiber, focus on adding fiber first before considering a prebiotic supplement.

Antibiotics kills the community and microbes in your gut leaving room for other pathogens to take over. So if youve recently been on an antibiotic a probiotic and perhaps a short course of prebiotic support can help rebuild your good bacteria.

Prebiotic-rich foods include chicory root, Jerusalem artichokes, garlic, onions, leeks, asparagus, bananas, apples, berries, oats, flaxseed, and legumes.

After all these years, the gut is still my Roman Empire — the thing I can’t stop thinking (and talking) about. But honestly, it deserves the obsession. When we feed it right, move a little, rest enough, and keep the gremlins in check, everything else just works better.

So if you catch yourself thinking about your microbiome the next time you’re in the produce aisle… welcome to the club.

As always, thank you for reading. I try to keep things practical and not make it feel like you’re reading a textbook, while still including the science. So forgive my corny analogies. They’re here to stay. 😉