Over the past couple of decades, both probiotics and prebiotics have become incredibly popular here in the U.S.  They can now be found in a variety of different food products and dietary supplements due to the growing body of evidence that they may benefit your overall health in multiple ways. 

From enhancing the function of your gastrointestinal tract to fighting off the common cold, researchers have identified a number of potential therapeutic applications for pro- and prebiotics.  

Before we dive into exploring the benefits though, let’s first take a look at what probiotics and prebiotics actually are and what sets them apart from one another.  

Probiotics vs Prebiotics: What’s the Difference?

What Are Probiotics?

Probiotics are living microorganisms that can be found in certain functional foods along with a variety of different dietary supplements.  When consumed in adequate amounts, some of them reach the intestine in an active state, where they’ve been shown to have a beneficial influence on the gastrointestinal tract.(1)

More specifically, probiotics have been shown to improve the microbial balance in your gut.  Your digestive tract is actually filled with microorganisms like bacteria and archaea which collectively make up your gut microbiota (AKA your gut’s microbial community).    

While this might sound like a bad thing, some of these microorganisms actually aid in important metabolic activities, helping our bodies to break down dietary fibers, synthesize vitamins, and metabolize various biochemicals, amongst other things.(2)

When added into your diet, certain probiotics can contribute to the population of beneficial bacteria in the gut, which in turn, can lead to significant improvements in the overall health and function of the digestive system (we’ll talk about this in more detail in the following section.(3)

To date, most research with positive findings has tended to involved microorganisms from the Lactobacilli and Bifidobacterium families, with several different varieties being reported to have therapeutic effects in randomized clinical trials (RCTs).(4)(5) While not exhaustive, the following list includes some of the most thoroughly investigated probiotics.  

List of Probiotic Microorganisms

Lactobacilli VarietiesBifidobacterium Varieties
L. acidophilusB. adolescentis
L. caseiB. animalis
L. crispatusB. bifidum
L. gallumarumB. breve
L. gasseri B. infantis
L. johnsoniiB. lactis
L.paracaseiB. longum
L. plantarum
L. reuteri
L. rhamnosus

What Foods Contain Probiotics?

Most of the main food products that contain probiotics are dairy-based products, including yogurt, ice cream, cheese, fermented milk, milk powder, and buttermilk, with yogurt, being by far the most popular probiotic food product currently on the market.(6)

While dairy-products are the most common probiotic food source, some other non-dairy — particularly foods that go through some type of fermentation — also contain probiotics.  Popular options include certain soy-based products, sauerkraut, kombucha, and some kinds of pickled vegetables, just to name a few.(7)

What Are Prebiotics?

Unlike probiotics, prebiotics are not living organisms.  Rather, they serve as substrates for probiotics in the gastrointestinal tract.  In simpler terms, you can think of prebiotics as food for the microorganisms in your gut, helping to provide them with the nourishment they need to live and grow.   

More specifically, prebiotics are non-digestible dietary fibers that have been shown to lead to beneficial changes in the composition and activity of your gut microbiota, which in turn, has been shown to confer certain health benefits.(8)

However, it’s important to point out that research on prebiotics is still developing.  While there have been some human trials that have demonstrated positive outcomes, to date most research investigating the effects of prebiotics has involved animals.

With that being said, to date research involving human participants has demonstrated that certain types of dietary fibers can enhance the activity and/or growth of bifidobacterium  — a particular family of probiotic microorganisms that have overwhelming been shown to have beneficial health benefits in humans.(9)(10)

What Foods Contain Prebiotics?

Fibrous food sources that have been shown to increase the activity and/or growth of beneficial prebiotic microorganisms include things like garlic, onions, leeks, asparagus, barley, oats, wheat bran, and flaxseeds, just to name a few.(11)(12)(13)(14)(15)

How Probiotics and Prebiotics Can Help With Your Gut Health

probiotics and prebiotics
photo by CDC

When it comes to your gut health, countless RCTs have demonstrated that probiotics can improve the function of your gut in multiple ways. 

In studies involving both healthy individuals and those with inflammatory diseases of the gastrointestinal tract, probiotics have been shown to aid in everything from diarrhea prevention to the management of abdominal pain and intestinal inflammation.(16)

While they have yet to be as thoroughly investigated, there is also a growing body of evidence that prebiotics may offer many of the same benefits as probiotics, with some research ultimately concluding that a combination of both pro- and prebiotics may in fact offer the greatest therapeutic benefit.(17)

Diarrhea

Probiotics

To date, several probiotics, including L. acidophilus, L. rhamnosus GG, L. delbrueckii, L. fermentum, and Saccharomyces boulardii, have been shown to be effective at ameliorating diarrhea in humans, with numerous RCTs demonstrating their positive effects.(18)(19)

For instance, one study published in Alimentary Pharmacology and Therapeutics found that taking a probiotic supplement featuring L. rhamnosus twice a day for 5 days led to the amelioration of diarrhea in children experiencing infantile diarrhea.(20)

There is also a sizable body of evidence that certain probiotics can help to treat diarrhea in adults as well.  For example, one meta-analysis involving 25 different RCTs ultimately found that the probiotics L. rhamnosus and S. boulardii helped to significantly reduce the development of diarrhea in adults on antibiotics — diarrhea is a side effect many people experience while taking antibiotics.(21)

Another meta-analysis published in the Journal of Travel Medicine and Infectious Disease found that the consumption of several different probiotics (of both the Lactobacilli of Bifidobacterium varieties) also helped reduce the occurrence of diarrhea amongst adult travelers — diarrhea is a common side effect experienced by individuals traveling to foreign destinations.(22)

Prebiotics 

While there has been significantly less scientific inquiry when it comes to the efficacy of prebiotics, there is also some evidence that they may help with diarrhea as well. For example, one review ultimately found that the prebiotics inulin and pectin (2 kinds of fibrous plant carbohydrates) were indeed effective at reducing the prevalence and duration of diarrhea in humans.(23)

IBS 

Probiotics 

There is also a considerable amount of evidence that probiotics can help to reduce the symptoms of Irritable bowel syndrome (IBS), which affects as many as 45 million Americans.

IBS is a commonly occurring gastrointestinal disorder characterized by things like flatulence as well as abdominal bloating and pain, amongst other things(24)

Several different probiotics, including  B. infantis, L. rhamnosus, B. breve, Propionibacterium freudenreichii, Bifidobacterium bifidum, and Escherichia coli have been shown to be effective at alleviating the symptoms of IBS.(25)

For example, one RCT published in Neurogastroenterology and Mortality found that 4 weeks of twice a day supplementation helped to significantly reduce flatulence in those who were given the probiotic L. rhamnosus.(26)

A 2011 study ultimately found that 4 weeks of consuming the probiotic Bifidobacterium bifidum significantly reduced abdominal pain, discomfort, and bloating in individuals diagnosed with IBS, leading to significant improvements in their overall quality of life.(27)

Another 2012 clinical trial came to a similar conclusion, finding that 12 weeks of supplementation helped to significantly reduce IBS symptoms amongst the 60 study participants who were administered a daily dose of the probiotic Escherichia coli.(28)

Prebiotics 

When it comes to prebiotics, there is a limited amount of evidence that certain kinds may also aid in alleviating the symptoms of IBS.  More specifically, findings from animal studies and a limited amount of human-based trials suggest that certain prebiotics such as guar gum and wheat bran may help to mitigate abdominal pain and inflammation.(29)

IBD

Probiotics

On top of IBS, there is also some evidence that probiotics may help to alleviate the symptoms of Inflammatory bowel disorder (IBD) as well.  Characterized by chronic symptoms such as watery and bloody diarrhea, intestinal inflammation, and abdominal pain, IBD is an umbrella term that covers disorders like ulcerative colitis (UC) and Crohn’s Disease (CD).(30)

Several different probiotic species, including L. rhamnosus, L. casei, B. bifidum, S. boulardii, and E. coli have all been shown to be effective at reducing and even alleviating the symptoms of IBD in human trials –  especially in trials involving UC.(31)(32)(33)

For example, one 12-month clinical trial involving over 300 participants ultimately found that a daily supplement of the probiotic E. coli was effective at maintaining remission in UC patients.(34)

Another RCT involving the probiotic L. rhamnosus came to a similar conclusion, finding that 12 months of supplementation was effective at preventing chronic intestinal inflammation, diarrhea, and abdominal pain in patients with UC.(35)

Prebiotics 

While there’s only a limited amount of evidence that comes from human trials, some research does suggest the prebiotics like inulin may also help with controlling the symptoms of IBD, particularly when it comes to chronic interstitial inflammation.(36) However, more well-designed human-based trials need to be conducted before we can really say for sure.  

Lactose Intolerance

Probiotics 

Research also suggests that some probiotics may help to significantly improve the symptoms of lactose intolerance, which is the most common kind of carbohydrate intolerance in the world.  Those who are lactose intolerant often experience symptoms such as bloating, diarrhea, abdominal distress, and flatulence.(37)

More specifically, research findings from human-based trials suggest that the probiotics L.casei and B. breve have beneficial significant and beneficial effects on lactose digestion, helping to reduce the severity and occurrence of symptoms such as diarrhea, bloating, and abdominal pain.(38)(39)

Prebiotics 

While most research has tended to focus on probiotics when it comes to treating lactose intolerance, one 2012 review does provide some limited evidence that a combination of both pro- and prebiotics may be the ideal approach when it comes to treating lactose intolerance.(40)

Other Health Benefits of Probiotics and Prebiotics

probiotics vs prebiotics
photo by Rachael Gorjestani

Probiotics, Prebiotics, and Lipid Metabolism

Several studies have demonstrated that probiotics may help to improve your lipid metabolism.  Microorganisms like L. bulgaricus, L. reuteri, L. acidophilus, and B. coagulans have all been shown to reduce serum cholesterol levels in human trials.(41)

Other clinical research has demonstrated that the regular consumption of probiotics like B. longum and L. acidophilus can also lead to significant declines in triglycerides and improvements in HDL cholesterol.(42)

There is also some evidence that prebiotics like xylooligosaccharides and fructooligosaccharides may help to decrease things like your total cholesterol and triglycerides as well.  

However, it’s important to point out that most of the positive findings come from animal studies.(43) With that being said, one 2010 trial involving humans did demonstrate a significant reduction in serum triglycerides in individuals with hypercholesterolemia.(44)

Probiotics and the Common Cold

Evidence from numerous clinical trials also suggests that probiotics may be helpful when it comes to fighting the common cold, which is an upper respiratory infection that regularly affects millions of Americans.    

Research findings suggest that several types of Lactobacillus and Bifidobacterium probiotics can help to bolster the immune system, which in turn can aid in the prevention of respiratory infections such as the common cold.(45)

For example, One review involving 13 different RCTs found that individuals who regularly consume a probiotic supplement ultimately experienced a significantly lower rate of acute upper respiratory tract infection in comparison to those who were only given a placebo. And amongst those in the probiotic group who did still experience symptoms, they were ultimately less severe and of shorter duration in comparison to the placebo group.(46)

Another 2012 meta-analysis involving school children ultimately found that compared to a placebo group, children who regularly consumed the probiotics L. acidophilus and B. bifidum had a significantly lower risk of developing symptoms including fever, cough, and nasal congestion and were overall almost 20% less likely to come down with the common cold.(47)

Prebiotics and Obesity

Research shows that your gut’s microbial population has a major influence over how well your body is able to harvest and store energy, and those who are obese tend to have microbiotas that are far less efficient at utilizing the calories in their diets.  

However, evidence from recent human trials has demonstrated that prebiotics — in the form of fibrous foods — can help to improve the efficiency of your gut’s microbial population when it comes to utilizing and storing energy.(48)(49)

On top of that, it’s also been well-documented that a high fiber diet can help to increase your satiety, which, in turn, can reduce your overall daily calorie intake, leading to significant amounts of weight loss over time.(50)

Prebiotics and Mineral Absorption 

There is also some evidence that prebiotics may help to increase the body’s ability to absorb certain minerals — minerals are especially important for maintaining the normal function of most of your body’s major systems.  

For example, one study involving over 100 adolescents ultimately found that consuming the prebiotic inulin fructans (a fibrous plant carbohydrate) helped to significantly improve calcium absorption and bone mineral density at the conclusion of the 12-month study.(51)

Probiotic vs Prebiotic Supplements: Which One Should You Take?

While you can get a healthy supply of both pre- and probiotics through the foods you eat in your diet, they can also be obtained through dietary supplements.  

As far as choosing between a prebiotic and probiotic supplement, if you could only pick one, it would have to be the probiotic — at the end of the day, there’s far more clinical evidence to support the use of probiotics in the treatment of gastrointestinal distress.  But the good news is that you don’t have to choose between one or the other.  

 Known as  “synbiotics”, supplements that combine both pre- and probiotics are growing in popularity here in the U.S and it’s continuing to become more and more evident that a supplement that combines both may ultimately provide the greatest benefit not just to your gut but to your overall health. 

However, an important thing to pay attention to when selecting a symbiotic or probiotic supplement is the viability of the microorganism(s) in the product.  I.e. the particular strain(s) of probiotic(s) in the supplement must be able to stay alive under the manufacturing, and storage conditions, so that it remains active by the time it gets to you.  That’s why you only want to choose reputable products that are manufactured and distributed according to the highest standards.   

Additionally, you’ll also want to make sure that you choose a product with ingredients and dosages that have been well-demonstrated in reputable scientific studies.  You want to be especially certain that you’re only taking proven ingredients at clinical doses if you want to see real, measurable results.