We get asked constantly… What is the difference between probiotics and prebiotics?

The reason for confusion is pretty obvious. Not only do the words differ by only one letter, but they target similar benefits: improving overall health by improving digestive health through nourishing a healthy colon.

We’ll summarize the similarities and differences between prebiotics and probiotics here, then we’ll discuss each item in a bit more detail:


Prebiotics are a very special form of dietary fiber.Probiotics are living bacteria intended to benefit colon health.

Prebiotic Fiber is not affected by heat, cold, acid or time.Probiotics must be kept alive to create health benefits. They can be killed by heat, acid or simply the passage of time.

Prebiotics nourish the thousands of good bacterial species already living in the colon.Probiotics contain from one to a few species of bacteria which are added to the colon when they are ingested (eaten).

Prebiotic Fiber is a naturally-occurring substance, found in thousands of plant species (though mostly in very small amounts).Probiotics occur naturally in fermented foods like yogurt or sauerkraut. Some companies have also engineered “proprietary” bacteria which they have patented and promote.

Prebiotics foster an environment in the colon which is hostile to bad bacteria.Probiotics may impact bad bacteria by crowding them out.

The benefits of prebiotics are supported by extensive researchThe benefits of probiotics are supported by extensive research

Both Prebiotics and Probiotics must be ingested in sufficient quantity to have an impact, and dietarily speaking both should not carry an excessive “load” of sugar, calories, carbs, etc. out of proportion to their benefit.



Prebiotics are nondigestible substances that pass through the stomach and small intestine unchanged. Many substances have been proposed as prebiotics, but thus far only two fructooligosaccharides: oligofructose and inulin, meet the complete medical definition of “prebiotic”. The compound created from these two prebiotics together is called Oligofructose-Enriched-Inulin and is considered a “full-spectrum” Prebiotic. So when we say “prebiotics” we mean those two substances only.

Other “possible” prebiotics ranging from polydextrose to isomalto-oligosaccharides do not have enough research or proven benefit to qualify. Some foods presented as “prebiotics” in and of themselves simply contain prebiotics. For example we often see honey presented as “a prebiotic,” while it is more accurate to simply say that honey contains a small amount of prebiotics (as do many other foods).

Prebiotics enter the colon where they nourish beneficial bacteria. These beneficial bacteria number in the TRILLIONS in your colon, and there are thousands of different species of good bacteria. The beneficial bacteria, typically within the hundreds of species under the Lactobacillus and Bifidobacter families, create many health benefits through their action in the colon.

Probiotics are supplements that contain living organisms, bacteria. While many people now call the actual bacteria “probiotics” this is not technically accurate. A Probiotic is the supplement containing these bacteria. Once consumed and in your system, the bacteria are just “bacteria” not “probiotics.” However, for simplicity’s sake, we will occasionally refer to the bacteria themselves as “probiotic”

Typically these bacteria are the same Lacto- and Bifido- bacteria that are nourished by prebiotics. However, a probiotic supplement typically contains just a few strains – or even just one – of bacteria rather than the hundreds that exist in your colon. Nobody is quite sure if favoring these few strains over the others has unforeseen consequences.


Prebiotic:  Fiber is not affected by heat, cold, acid or time.

Probiotics:  Must be kept alive to do any good and can be killed by heat, acid or simply the passage of time.

Prebiotics benefit from their simplicity. They are, simply, very special fibers that nourish the good bacteria while not helping bad bacteria. Because of this, they are pretty impervious to damage. Heat does not harm them. They don’t “die” just from the passage of time. Acid does not harm or degrade them.

Probiotics by contrast are living organisms. If they are no-longer-living (AKA dead!) when they reach your colon, they cannot provide any health benefit. Probiotics therefore must be carefully sustained. They must not be subjected to excessive heat during transport and warehousing. They should typically be refrigerated to ensure the bacteria remain relatively dormant and don’t die simply from “old age”. And the bacteria can be killed by acid.

This latter is significant when you take them: That’s because your stomach is a rather antibiotic environment. The powerful acid of the stomach kills most bacteria. If you happen to eat a little Salmonella or E. Coli bacteria, that’s a good thing! But the good guys die too. Probiotic supplements often counteract that with capsules that are claimed to ‘get through’ the stomach before dissolving. Or, they address it through sheer numbers: Some probiotics offer tens-of-billions of bacteria per dose, with the intent that enough make it through to take hold.

Do not overlook the impact of heat either. ANY product you buy that has been cooked or pasteurized (i.e. most dairy and canned goods) CANNOT by definition have any living good bacteria (unless they have been added back later – as with some yogurts). Also, if you cook probiotic food (e.g. you use yogurt in a cooked recipe – perhaps a sauce on the stove) the bacteria will also be killed.


Prebiotics nourish the thousands of good bacterial species already living in the colon.

Probiotics contain from one to a few species of bacteria which are added to the colon.

Your colon contains trillions (with a “T”!) of bacteria – more than all the ‘human’ cells in your body. More than all the stars in the milky way galaxy. It is a number possibly too big to really comprehend. There are hundreds, if not thousands, of strains of bacteria in your colon. In fact, it is likely that each person’s colon “microbiota” is as unique as fingerprint.

Prebiotics nourish all the good bacteria, particularly in the lacto- and bifido- families, preserving your “fingerprint”.
Probiotics typically contain a few, or even just one, strain of bacteria. These bacteria are typically from the same bifido- and or lacto- families, but may or may not match your particular microbiota. One concern with probiotics is whether favoring a few strains that come in supplements might crowd out other beneficial strains along with the bad bacteria. For example, by favoring a strain that reduces diarrhea, are we inadvertently ‘crowding out’ a strain that helps you absorb key nutrients like Calcium or Magnesium?