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What Are Postbiotics?

Postbiotics is a relatively new term that’s been coined to refer to the metabolic byproducts of those probiotic bacteria, which seem to be responsible for many of the beneficial effects of probiotics.

By
Monica Reinagel, MS, LD/N, CNS
4-minute read
Episode #618
The Quick And Dirty
  • Postbiotics are beneficial compounds, such as short chain fatty acids, produced by probiotic bacteria.
  • These compounds are responsible for many of the benefits associated with probiotics.
  • Because they do not contain live bacteria, postbiotics could be used therapeutically in immune compromised individuals.

Max writes:

I’ve heard you talk about prebiotics and probiotics but I just came across a reference to postbiotics. What are these and how do they affect our health or nutrition?

All three of these terms (prebiotics, probiotics, and postbiotics) have to do with the trillions of bacteria that live and work in our digestive tracts. Understanding the complex interactions between us and our unseen guests has become the leading edge of nutrition and health research. Everything we thought we knew about nutrition, digestion, immunity, and metabolism is now being re-evaluated through the lens of the microbiome. Who knew these little critters were so important?

Everything we thought we knew about nutrition, digestion, immunity, and metabolism is now being re-evaluated through the lens of the microbiome.

Probiotic vs. prebiotic

Probiotic refers to the bacteria that we get from foods (and supplements) that are thought to have beneficial effects in the body. The lactobacillus and bifidobacteria that we get from yogurt, for example, are some of the more common types of probiotic bacteria.

RELATED: Fermented and Cultured Foods

Prebiotic refers to the foods we consume that also provide fuel for the bacteria that inhabit our intestines. This fuel is mostly in the form of plant fibers from vegetables, grains, and legumes. We humans lack the enzymes to digest these fibers, so they arrive more or less intact in the large colon. Unlike us, the bacteria living there have the enzymes to digest them. Eating more of these foods can bolster the health and vitality of your intestinal population.

RELATED: Are Probiotic Foods a Waste of Time?

Synbiotic is another term you might come across. This refers to a product that combines probiotic bacteria with prebiotic fibers—sort of the way you might buy a product for your lawn that includes both grass seed and plant food to help it grow.

What are postbiotics?

Postbiotics is a relatively new term that’s been coined to refer to the metabolic byproducts of those probiotic bacteria. Metabolic byproducts is sort of a cleaned-up way of saying "waste products." But it just goes to show you that one organism’s trash is another organism’s treasure: These bacteria produce and excrete compounds into our digestive tracts, which seem to be responsible for many of the beneficial effects of probiotics.

As they go about their cellular business, bacteria produce (among other things) hydrogen peroxide. This may protect us from salmonella and other pathogenic bacteria or yeasts that might be hanging around the neighborhood looking for trouble. 

When you have more beneficial bacteria, they produce more acetic acid, which helps to regulate your blood sugar and gives your metabolism a modest boost.

Short-chain fatty acids are also byproducts of bacterial metabolism. One of these, acetic acid, is the substance that gives vinegar its distinctive tang. And this may be one of the ways that a healthy microbiome can promote healthy body weight. When you have more beneficial bacteria, they produce more acetic acid, which helps to regulate your blood sugar and gives your metabolism a modest boost.

RELATED: What Apple Cider Vinegar Can (and Can't) Do For You

Butyric acid is another short-chain fatty acid produced by the gut bacteria. It helps promote colon health by providing an energy source for colon cells.

Other postbiotic compounds include beta-glucans, certain vitamins, various enzymes, even fragments of cell walls that activate the host's immune system. 

How can postbiotics be used to improve health? 

We still have a long way to go in understanding how our microbiota influence our health and, conversely, how we can influence our microbiota. But understanding more about these postbiotic compounds may be a big part of the picture.

For example, they may make it easier to assess the health of our microbiome and to see how it is responding to our interventions. Instead of having to count and catalog every strain of bacteria present in a subject’s gut—many of which aren’t really doing anything one way or the other—it might be simpler and more direct to just measure the presence of these active compounds. There are even some scientists trying to develop a sort of "smart toilet paper" that would make this easier to do.

Postbiotic compounds are being studied for their anti-inflammatory, immune-modulating, cardioprotective, and anti-cancer effects.

Postbiotics might have direct therapeutic potential as well. Instead of trying to alter the makeup of our intestinal population with food, supplements, or even fecal transplants, we might be able to administer these postbiotic compounds directly. Perhaps they would be useful when patients require antibiotics or other microbiome-disrupting therapies.

Postbiotic compounds are being studied for their anti-inflammatory, immune-modulating, cardioprotective, and anti-cancer effects. Researchers are also looking at the use of postbiotics to reduce inflammation and so-called "leaky gut syndrome," and even improve athletic performance.

RELATED: Is Leaky Gut Syndrome a Legitimate Diagnosis?

One advantage of using postbiotics instead of prebiotics is that it does not require introducing live bacteria into the system. This could be helpful for immune-deficient or compromised patients that might not be able to take live probiotic bacteria. And because postbiotics don't require that live bacteria to be present in order to be effective, they are also a lot easier to manufacture and store. 

How to get more postbiotics

There are some foods that already contain some of these postbiotic compounds. Vinegar, as I mentioned before, is a source of acetic acid. Butter and cheese contain butyric acid. Including these foods in your diet, in moderation of course, can supplement what’s being produced by your gut flora.

We may also soon see functional foods that have been fortified with postbiotic compounds in order to boost their beneficial effects. For example, infant formulas fermented with lactic acid-producing bacteria could be a source of postbiotic compounds without actually containing live bacteria. Such formulas have been found in early research to reduce symptoms of food allergy in susceptible infants.

But for now, I think your best bet may be to continue to consume those pre- and probiotic foods on a regular basis, which will help keep your microbiome robust and healthy.

Sources +

About the Author

Monica Reinagel, MS, LD/N, CNS

Monica Reinagel is a board-certified licensed nutritionist, author, and the creator of one of iTunes' most highly ranked health and fitness podcasts. Her advice is regularly featured on the TODAY show, Dr. Oz, NPR, and in the nation's leading newspapers, magazines, and websites. Do you have a nutrition question? Call the Nutrition Diva listener line at 443-961-6206. Your question could be featured on the show.