What Are Postbiotics? Definition, Benefits, and Side Effects

Most health-conscious people have known about the microbiome benefits of probiotics and prebiotics for years.

But have you heard of postbiotics? They’re not a friendly bacteria or fiber, but they are intimately related to pre- and probiotics.

In this article, you’ll learn what postbiotics are, their relation to pro- and prebiotics, their potential health benefits, how to get more in your diet, and possible side effects.

What are Postbiotics?

Postbiotics are end-products that come from the metabolism of probiotics and prebiotics.REF#3284

Research has shown that postbiotics may benefit the gut microbiome and other bodily systems.

If you’re a fan of traditional nutrition philosophies, you may be familiar with the postbiotic butyrate, a short-chain found in dairy products from grass-fed cows and other foods.

Another example of a postbiotic produced from a probiotic is reuterin, produced by the gut bacteria strain, L. reuteri—found in many probiotic formulas, which supports optimal intestinal permeability and gut barrier function.REF#3285

Examples of Different Types of Postbiotics Include:

• Bacterial lysates: These come from chemical or mechanical degradation of Gram-positive and Gram-negative bacteria commonly found in the environment. They are believed to support the gut-lung axis.

• Cell wall fragments: Certain bacterial cell wall fragments, such as bacterial lipoteichoic acid (LTA), may support immune function.

• Cell-free supernatants: A liquid mixture of metabolites sourced from microbial growth and the residual nutrients of specific bacteria/probiotics.

• Enzymes: These produce beneficial antioxidant compounds, such as glutathione, which are of particular interest in postbiotic research.

• Exopolysaccharides (EPS): A group of substances produced by bacteria/probiotics currently used in the food industry as stabilizing, emulsifying, and water-binding agents. Βeta glucans are a type of EPS.

• Short-chain fatty acids: These are products of fermentation of plant polysaccharides by intestinal microbiota. Some examples include acetic, propionic, and butyric acids (butyrate), which are believed to support various aspects of gut, immune, cardiovascular, intestinal barrier, and metabolic function.

• Other metabolites produced by gut microbiota: Including vitamins such as B and K, phenolic-derived metabolites, and aromatic amino acids, which play various roles in intestinal, immune, and different gut-organ/system axis functions.

Since postbiotics come from the digestion of probiotics and prebiotics, we obtain them from probiotic- and prebiotic-rich foods, like cultured foods and fiber-rich foods.

However, the health and function of the gut microbiome likely play a role in how much and what types of postbiotics our body manufactures.

5 Benefits of Postbiotics for Gut Health, Immunity, Metabolic Function, & More

There is still much to learn about the many types of postbiotics excreted by pre- and probiotic activity, how they work, and the role gut microbiota diversity plays in their existence and function.

However, researchers are optimistic about their potential health benefits.

1. Postbiotics May Support Immune Function

Research suggests postbiotics, such as butyrate, exopolysaccharides (EPSs), and others, may support various aspects of immune function.

For example, EPSs may support immune regulations (also known as immune modulation) by promoting normal function of T and NK lymphocytes. Beta-glucans (a type of EPS) have also demonstrated immune-supportive activity.REF#3286

Cell wall fragments are also known to elicit various immune responses which may benefit the host.REF#3286

Butyrate, a type of short-chain fatty acid, has also been documented for its potential role in supporting immune regulation.REF#3287

Bacterial lysates are believed to promote the functional connection between the intestinal immune system and the respiratory system.

Although more research is needed to understand how postbiotics interact with the immune system, preliminary research suggests they play an essential role in immune function via the gut-immune system.

2. Postbiotics May Support Digestive Function

There has been ample research demonstrating how probiotics can positively affect digestive system function.

Therefore, it stands to reason that postbiotics would perform similarly.

Although the research on postbiotics and digestion is less robust than pre- and probiotics, studies suggest postbiotics may support diverse facets of digestion, including: REF#3288 REF#3289

• Intestinal barrier function
• Gut microbiome diversity
• Digestive inflammatory response

Although more research is needed, preliminary studies suggest postbiotic supplements may have advantages over probiotic supplements for digestive function, in that they are more stable and able to survive gastric juices and antibiotics.REF#3289

3. Postbiotics May Support Metabolic Function

Several studies suggest that specific postbiotics, including butyrate, microbial-derived vitamins, and other short-chain fatty acids may support normal metabolism and signaling pathways, including: REF#3290 REF#3291 REF#3292

• Normal lipid metabolism 
• Normal insulin sensitivity and glucose tolerance
• Normal appetite
• And normal glutathione levels which have antioxidant benefits for the metabolic and cardiovascular systems

This isn’t surprising given the growing body of research showing a link between probiotic and prebiotic consumption and various facets of metabolic function.REF#3293

More research is needed.

4. Postbiotics May Support Some Aspects of Cardiovascular Function

Cardiovascular and metabolic function are intimately linked. 

Therefore, based on what was discussed in the previous section, it should be no surprise that postbiotics may benefit your heart.

Specifically, emerging research suggests butyrate and kefiran (an exopolysaccharide produced by Lactobacillus kefiranofaciens) may support normal blood pressure and cholesterol function.

The short-chain fatty acid acetate may also have cardiovascular benefits due to its potential benefits for supporting normal appetite.

Antioxidants produced by postbiotic enzymes, such as glutathione, may also provide benefits via their inflammatory response support properties.

Various pre- and probiotics have also been shown to be potentially beneficial for heart function.REF#3294 REF#3295

This field of study is emerging, and more research is needed. 

5: Postbiotics May Have An Edge Over Probiotics

Probiotics, prebiotics, and postbiotics exist within a symbiotic relationship in the gut. 

Here’s a brief explainer of how this works:

• Probiotics are a type of friendly bacteria from the environment, foods, supplements, and beverages that colonize, nourish, and strengthen your gut microbiome and help keep bad bacteria and other pathogens out.
• Prebiotics, which come from specific fibers, resist digestion and ferment in the gut, where they become essential fuel for probiotics to survive and multiply.
• Postbiotics, as previously discussed, are the byproducts of pro- and prebiotic fermentation, which have their own unique properties and benefits.

All three of these have health-supportive benefits.

However, as we touched on earlier, research has shown postbiotic supplementation may have some advantages over probiotics, including: REF#3296

• Stability: Postbiotics are more stable, with a longer shelf life and better environmental tolerance than probiotics.

• Safety: Although pre-, pro-, and postbiotics are all considered very safe, postbiotics are equally adaptable to special populations, like newborns and sensitive people, and do not have any risks associated with live bacteria.

• Antibiotic-resistant: Postbiotics are not inhibited by antibiotics, so there is no risk of passing on drug-resistant genes, and they may provide added digestive benefits.

Ultimately, pre-, pro-, and postbiotics have potential health benefits depending on your unique situation and health goals.

Talk to your healthcare practitioner about the best options for you.

Side Effects & Possible Contraindications of Postbiotics

Like pre- and probiotics, postbiotics are considered very safe—especially within the context of postbiotics created from probiotic-rich foods.

However, if you’re taking additional probiotics to increase postbiotic production, you may experience temporary changes in digestion or digestive discomfort.

Since pre-, pro-, and postbiotics may affect immune function, always talk to your doctor or healthcare practitioner before trying to increase postbiotic levels via food or supplements if you have a pre-existing condition.

Your Postbiotic Recap

Postbiotics are beneficial byproducts of the fermentation of probiotics and prebiotics.

Some common examples of postbiotics include: 

• Short-chain fatty acids, like butyrate
• Vitamins like vitamins B and K
• Enzymes which produce antioxidants like glutathione
• Exopolysaccharides such as beta-glucans

Like probiotics and prebiotics, postbiotics may benefit digestion, immune function, metabolism, and cardiovascular function, but more research is needed.

The Best Ways to Increase Postbiotics in Your Gut are by: 

• Increasing pro- and prebiotic-rich foods, such as cultured foods
• Taking a probiotic/prebiotic supplement or probiotic/prebiotic/postbiotic supplement
• Taking care of your digestive health to optimize gut microbiome diversity and function. Some ways to do this may include:
• Eating a diverse diet
• Spending time outdoors
• Gardening
• Reducing Stress
• Getting enough sleep
• Avoiding over-sanitizing your environment
• Taking gut-supportive herbs like: 
• Licorice
• Peppermint
• Ginger
• Sweet wormwood
• Chamomile
• Black Walnut
• Bitters
• Fennel
• Triphala

Postbiotic supplements are generally very safe to take and can be found in various probiotic/prebiotics formulas.

If you have concerns about postbiotics or gut health, talk to your healthcare practitioner for individual recommendations.