Postbiotics Positive Gut
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Postbiotics: definition, health benefits, and supplements

Many people have heard about probiotics, the live bacteria that can be supplemented in support of health. Some people have heard about prebiotics, the nutrition (mostly fiber) for the microbes that are present in our gut. A few of you may know synbiotics, which is a combination of the pro-and pre-biotics. But not many people have heard about postbiotics yet. So let’s dive in today. What is the definition of a postbiotic, and are they healthy for us?

Postbiotics Positive Gut

The Definition of Postbiotics

Postbiotics are a relatively new find. Only since about 5 years have researchers started to pay more attention to this group of bioactive compounds. The term ‘postbiotic’ comes from ‘post’ which means ‘after’ and ‘biotic’ which means ‘relating to or resulting from living organisms’.

The International Scientific Association of Probiotics and Prebiotics (ISAPP) has released a consensus statement about the definition of postbiotics earlier in 2021. Which I used as the main source for this blog.

The official definition of a postbiotic is as follows:
‘Preparation of inanimate microorganisms and/or their components that confers a health benefit on the host’

Sound a little complicated right? This means that an effective postbiotic contains (a part of) dead bacteria and can also contain the products those bacteria have made in their life (like Short Chain Fatty Acids (SCFA)) but it must still have health-promoting effects.

Some bacteria have even been shown to have stronger health-promoting effects when they are dead than alive. And this is very valuable for the science of postbiotics.

Possible Health Effects of Postbiotics

There are 5 ways in which it is assumed that postbiotics can have a health benefit. (Illustrated in the picture below taken from the consensus statement)

  1. Through the modulation of the microbiota that is already present. The substances that the postbiotic contains (like lactic acid and short-chain fatty acids) are sources of nutrition for the gut microbiome and help create a healthy environment
  2. Improvement of the gut lining. The epithelial barrier is the gut lining that seperates the inside of our intestines from the inside of our body.
  3. Modulation of immune response. Postbiotics can interact with receptors in the gut lining and help modulate the immune response.
  4. Modulation of systemic metabolic responses. Effects on the metabolic responses is started by the metabolites or enzymes inside and on the surface of the inactivated micro-organisms. One example is, that it might help break down bile acids.
  5. Signalling via the nervous system. Microorganisms can produce different neuroactive compounds that can work in the enteric and central nervous system. This has the potential to modulate behavoir and cognitive function in animals and humans. Think of serotonin, dopamine and GABA. Also precursors for neurotransmitters can be made.

Remember, that this is only speculation, and evidence still needs to arise.

Some small studies have already been done on humans. One of these studies showed that orally administered inactivated lactic acid bacteria can help get rid of helicobacter pylori infection, a reduction in Irritable Bowel Syndrome (IBS) symptoms), a reduction in unexplained diarrhea, and reduction of the negative effects of stress.

A study with heat-inactivated Bifidobacterium bifidum MIMBb75 also showed a reduction in IBS symptoms. But all studies still need more data and research to actually make recommendations on.

Postbiotics positive gut
Salminen, S., Collado, M.C., Endo, A. et al. Publisher Correction: The International Scientific Association of Probiotics and Prebiotics (ISAPP) consensus statement on the definition and scope of postbiotics. Nat Rev Gastroenterol Hepatol 18, 671 (2021).

Postbiotics in our food

Postbiotics can be found naturally occurring in our food. Any product that once contained a large number of bacteria, will contain postbiotics. Those bacteria can still be present, but ‘dead’. For example, when sourdough bread gets baked, a product gets stored for a longer period of time, or a yogurt gets pasteurized. Or they will still be alive and will have made many bioactive compounds (like lactic acid, SCFA, and other metabolites) in their life, that are present in the product.

It is thought that these substances that are produced by the bacteria in a product, can have the same effect as those same substances that are created by our gut microbiome. Although, this does need more research.

To qualify as a postbiotic and be used (and sold) as such, the bacteria must be qualified before inactivation. Unknown micro-organisms don’t qualify as postbiotic. It is important to know for sure if a micro-organism is health-promoting or at least harmless.
A sourdough bread that is made with a sourdough starter that has not been properly identified may not be named a postbiotic. But a sourdough bread made with a sourdough starter that has been identified could be postbiotic.

Postbiotic Supplement

Nowadays there are also supplements on the market, where you take the post-fermentation products.
These are not officially postbiotics, according to the ISAPP definition. A postbiotic MUST contain the cellular biomass of the bacteria. A supplement with only the short-chain fatty acid Butyrate, for example, is a butyrate supplement and not a postbiotic.

Creating a postbiotic supplement or product is far easier than making a probiotic one. When you don’t have to worry about keeping the bacteria alive (like with a probiotic), storing and transport suddenly becomes much easier. There is a downside to postbiotic supplements that are on the market nowadays. They are often not independently researched. So if there are claims on the packages, that is usually just the manufacturer’s testing.

It is important to buy properly tested products, because some bacteria may create endotoxins which are still problematic for humans even after the bacteria has passed. So only buy from manufacturers you trust and that have tested their products thoroughly.

Have you ever tried postbiotics yet? What is your experience? Let me know in a comment below!

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