Prebiotics vs Probiotics: Key Differences Explained

Did you know that there are about 38 trillion bacteria living inside your body? Yes, that's 38,000,000,000,000* — a mind-boggling number of microscopic organisms. These bacteria, along with other microbes like viruses and fungi, form communities known as microbiomes. 

Your microbiomes exist in various parts of your body, such as the gut, skin, mouth, and even the vagina. While they're invisible to the naked eye, these microorganisms play an enormous role in maintaining your overall health, from supporting your immune system to aiding in digestion.

One popular way to support your microbiome (and gut health) is by incorporating probiotics and prebiotics into your diet. But what exactly is the difference between prebiotics vs probiotics, and why are they important? Let's break it down.

What are probiotics?

Probiotics are living bacteria and yeasts that are beneficial to your health, especially your digestive tract. Though it might seem strange to consume bacteria on purpose, these "good" microbes help balance your body’s microbiome, especially in the gut. A well-balanced microbiome can fend off harmful pathogens like bad bacteria, viruses, and fungi that may otherwise cause illness or discomfort.

The most common bacteria found in probiotic products belong to the genus Lactobacillus and Bifidobacterium. These helpful bacteria occur naturally in fermented foods like: 

• Yogurt
• Pickled vegetables (like sauerkraut and kimchi)
• Miso
• Kombucha
• Tempeh
• Kefir

When you consume probiotic foods, they add to the population of good gut bacteria, helping to restore the balance that might be disrupted by factors like antibiotics, illness, or poor diet.

The health benefits of probiotics are pretty well-researched. For example, some studies show that probiotics may improve gut health by alleviating symptoms of irritable bowel syndrome (IBS) and reducing diarrhea — although researchers are still trying to understand how probiotics do this. 

Emerging research also suggests that probiotics (and the gut microbiome in general) may affect mental health by creating small molecules that can signal to the brain. This connection is called the gut-brain axis. A balanced microbiome has been linked to reduced anxiety, depression, and even improved cognitive function — but more research is needed to understand the link between gut health and mental health. The gut microbiome can also affect our lungs, heart, or skin. It can even affect your hormones which has a domino effect all over the body.

What are prebiotics?

Unlike probiotics, prebiotics aren’t living organisms. Instead, they’re specific types of dietary fiber that act as food for the good bacteria already living in your gut. 

These fibers pass through your digestive system undigested until they reach the colon, where they are fermented by the gut bacteria. This fermentation process helps feed and grow the good bacteria, allowing them to thrive.

Prebiotics are found naturally in a variety of plant-based foods. Some of the most common sources include:

• Whole grains
• Bananas
• Garlic
• Onions
• Soybeans
• Artichokes 

By including these foods in your diet, you provide the fuel that probiotics need to grow and maintain a healthy balance in your gut microbiome.

Research shows that prebiotics can enhance digestion, improve calcium absorption, and bolster the immune system by encouraging the growth of good bacteria like Lactobacillus and Bifidobacterium. Additionally, they help produce short-chain fatty acids during fermentation, which have been shown to reduce inflammation in the gut and may even lower the risk of developing certain chronic diseases.

How do they work together?

The relationship between probiotics and prebiotics is symbiotic, meaning they work together to improve your health. Think of probiotics as the good bacteria that keep your gut healthy, while prebiotics are the food that keeps those bacteria strong and thriving.

Without enough prebiotics, the probiotics you consume or already have in your body may not be able to function optimally. Similarly, prebiotics alone won’t have much of an impact if there aren’t enough good bacteria present to feed on them. This is why maintaining a diet rich in both probiotics and prebiotics is essential for a well-functioning microbiome.

Should you take probiotic supplements for gut health?

Everyone’s microbiome is unique. What works for one person’s gut health may not work for another’s, which is why there’s no one-size-fits-all solution when it comes to probiotics and prebiotics. 

Factors like genetics, diet, lifestyle, and even where you live can influence your microbiome's composition. Researchers are still trying to understand what a “healthy” gut microbiome looks like! Although some research shows that taking probiotic supplements can help in certain cases (for example, if you have gut issues), the jury’s still out on whether everyone would benefit from taking probiotic supplements. 

Probiotic supplements have been popular for a while, but many probiotics aren't regulated and don't have much research behind them. Since probiotics are considered dietary supplements and not drugs, the U.S. Food and Drug Administration (FDA) doesn't monitor their production or marketing. This means it's hard to tell if the probiotics you find in stores or online are any good (in terms of safety or efficacy). In fact, some of the lower-quality products might not even have the amount or strains of probiotic bacteria they claim to have on the label. 

So, unless your healthcare provider has recommended you take a probiotic supplement, you’re likely better off saving your money and focusing on eating a healthy diet rich in prebiotic and probiotic foods, such as whole grains and leafy greens.   

The vaginal microbiome

While much of the focus on probiotics and prebiotics revolves around gut health, it’s important not to overlook other microbiomes in the body, such as the vaginal microbiome. 

The vaginal microbiome plays a significant role in the immune health of anyone with a vagina. A well-balanced vaginal microbiome helps protect against infections like bacterial vaginosis (BV), yeast infections, and even sexually transmitted infections (STIs), and vaginal probiotics can be an important part in maintaining vaginal health. 

Unfortunately, much of the available microbiome research focuses on men, which can make it difficult to apply the findings to women’s health. As a result, there’s a growing movement to ensure that research reflects the diverse needs of all individuals, not just men. Evvy is part of this mission to redefine the research default and ensure that women’s microbiomes, particularly the vaginal microbiome, are studied and understood in greater depth.

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FAQ

Is it better to take a prebiotic or probiotic?

Deciding between taking a prebiotic or a probiotic depends on your specific health needs and the state of your microbiome. Both prebiotics and probiotics play different but complementary roles in maintaining gut and overall health, so one isn't necessarily better than the other — it’s more about what your body needs. Probiotics may be helpful if your gut microbiome is imbalanced or lacking in good bacteria, such as experiencing digestive issues like bloating, diarrhea, or irritable bowel syndrome (IBS). If you’re looking to increase the population of good bacteria in your body, probiotics might be more helpful. On the other hand, prebiotics are essential if you already have a good base of healthy bacteria but want to support their growth and activity. If your diet is low in fiber or you want to help probiotics thrive, taking a prebiotic can encourage a healthier, more robust microbiome over time. Some people benefit from taking both, as they work in synergy. However, everyone's microbiome is different, so the best approach depends on your individual health, diet, and any specific conditions you might be addressing. There's little evidence that taking prebiotic or probiotic supplements will have any benefit if you're not experiencing symptoms or digestive issues. It’s also a good idea to consult a healthcare provider or use tools like microbiome tests to determine whether your body would benefit more from a prebiotic, probiotic, or both.