We have heard the term “probiotics” which refers to the live bacteria and yeast that help maintain or improve the healthy microflora in the gut. We may also be familiar with “prebiotics” which are the fermented foods that FEED these amazing bacteria, as well as viruses and yeast species. But postbiotics are also part of the gut-brain axis that needs to be discussed. All three of these types of “biotics” (from the Greek “bios” meaning “for life”) should be part of the discussion when it comes to our gut, which is the largest organ in the body that holds 70% of our immune system. So it needs to be happy, healthy and well cared for.
So what are “postbiotics’? They are defined as the nonviable bacterial or metabolic products from microorganisms that have biological activity in the host. It is basically the waste left behind by the digestion of pre and probiotics. Some postbiotics from non-viable microorganisms come from Lactobacillus species. These precision probiotics are strains that have precise effects in the body and brain. For instance, there is growing evidence of antidepressant effects of GABA secreted by Lacticaseibacillus rhamnosus and Lacticaseibacillus casei that travels through the nervous system and crosses the blood-brain-barrier altering the expression of GABA receptors that may lead to a reduction in depression. Another GABA secreting bacteria, Levilactobacillus brevis may help with sleep as well as reducing depression.
The fact is that we make more neurotransmitters in our gut than the brain. Certain bacteria can send serotonin, GABA, dopamine and norepinephrine to the brain. Postbiotics are especially helpful in people who are sensitive to probiotics, because they are less likely to cause gas and bloating. It also helps those whom are immune compromised as they pose no risk for infection.
As I mentioned before, postbiotics can include inactivated probiotics or cell wall fragments. This includes metabolites such as short chain fatty acids (SCFA), vitamins (folate, B12, Vitamin K), enzymes and bacterial lysates and more. The most common postbiotics from nonviable organisms come from lactobacillus species, Bifidobacterium species and Saccharomyces (yeast) and bacillus species. The SCFA’s, primarily sodium butyrate are fuel for the microbiota and help regulate GI function, blood pressure and act as intermediaries between the gut and the brain.
Postbiotics have many functions: they strengthen the tight junctions in the gut, improve leaky gut, help with immune modulation, protect from infection and mitigating allergies.
They also help support healthy metabolism by lowering the risk of insulin resistance and the regulation of hemoglobin A1c (blood sugar levels). More and more human studies are being conducted and have observed improvements in irritable bowel syndrome symptoms, immune support (reducing risk of upper respiratory infections and less allergic symptoms), and metabolic support by lowering systolic blood pressure and decreasing elevated liver enzymes as well as total cholesterol and LDL.
Postbiotics are an important addition to gut-brain therapeutics. More research is needed but the existing studies show that dosing varies according to the specific postbiotic and the conditions being used to treat. They are effective in supporting the gut and building foundational health from the gut up.
References: Fidler, M. “Postbiotics: The newest addition to gut-brain therapeutics”. Element by Emerson Ecologics. Issue #6 p. 30-33. 2022.
Lowry, C. “Understanding the Gut Brain: Stress, Appetite, Digestion and Mood”. Conference in Lafayette CO. 3/13/2023.
Golen, T. “What are Postbiotics?” Harvard Health Publishing: Harvard Medical School. Nov. 1 2021.