More on Probiotics

More on Probiotics

What are probiotics?

Probiotics are living bacteria and yeasts which are consumed as a supplement, unlike pathogenic bacteria, probiotics are referred to as “good bacteria” and do not cause disease but instead contribute to the function of the gut.  The gut microbiota consists of over 200 bacteria, fungi and yeasts, thought to be fundamental to the health of the host (us humans!). The effect of gut bacteria on health and disease is a widely researched topic implicating the gut microflora in metabolism, hormone balance, skin health and in 2020, researchers at Oxford University found that the different types of bacteria in our gut may even be responsible for our personality and social behaviour, finding that those of us who suffer from high stress or anxiety actually have lower microbiome diversity, while those with a greater social network had higher diversity (Johnson 2020). So it’s not surprising that supplementing our gut microbiota with probiotics has become popular! 

How is the strength of probiotics measured? 

Like other food supplements, probiotic doses are dependent on their strength. They are measured using colony forming units per gram (cfu/g), this is the amount of bacterial colonies which are contained in a single gram of probiotic supplement. The higher the cfu/g, the more live bacteria the probiotic contains – often probiotics come in a very concentrated form – in the hundreds of billions of cfu/g, which means billions of live bacteria in just one single gram of product!

How are they made?

So where do these small but mighty supplements come from? The first probiotic to be discovered is thought to be Lactobacillus bulgaricus, a strain of bacillus found in Bulgarian yoghurt in 1905, by microbiologist Stamen Grigorov. It was then Élie Metchnikoff who found that in rural Bulgaria, peasants living in extreme poverty were unexpectedly living into old age and connected this to their diet, rich in fermented foods and yoghurts (Mackowiak, 2013). This discovery prompted research into the bacteria already living inside humans, thought to be beneficial to health. Eventually these bacteria were then isolated from human faeces, skin and bodily fluids of healthy individuals and cultured on media such as dairy or barley to allow the bacteria to multiply before being fed back to humans as a supplement. 

Thankfully, techniques have since developed and the use of human source material is no longer necessary! Now, probiotics are produced in huge quantities using vegan media. The process of probiotic production begins with a single pure strain of bacteria, used to inoculate a fermentation tank filled with sterilised nutrient media, this commonly includes water, carbohydrates and micronutrients that the bacteria will need to grow. The nutrient media is tailored depending on what the microorganism requires for growth and performance, for example Lactobacillus johnsonii prefers higher levels of free amino acids and oligosaccharides, while Lactobacillus plantarum requires fewer specific nutrients in the growth medium (Fenster et al., 2019). Once the nutrient media is perfected, fermentation begins, causing the bacteria to multiply until they reach a desired strength. The microorganism and nutrient media mixture is then centrifuged in order to separate the probiotic cells from the unwanted growth media. Lastly but importantly, the probiotics are freeze dried. As the name suggests, the probiotics are frozen before a vacuum is created and then heat is added, forcing the frozen water in the probiotic to turn into vapour – completely removing moisture and causing the product to dry. This is a key step in the production of probiotics, resulting in the inhibition of metabolic activity and allows the probiotics to be stored in a dormant state, in turn improving the shelf life of food supplements made from them (Kiepś & Dembczyński, 2022). 

Storage and best practice

To keep probiotics at their strongest they must be protected from harsh conditions in their storage environment as otherwise the dose size can be hugely affected. As probiotics are living microorganisms, sunlight, oxygen and heat exposure can cause them to go into a state of stress or even kill the live bacteria. It is recommended that probiotics are stored at temperatures of −20 and 4 °C to ensure their survival for more than 3 months (Cabello-Olmo et al., 2020). So what does this mean if the supplements are sat on shop shelves at ambient temperatures? It is often a good idea to manufacture probiotic supplements with overage to ensure some probiotics can be lost while the product still maintains its labelled quantity (Probiotics Retailer Education White Paper).

In addition, introducing moisture or storage in a humid environment may cause the probiotics to reanimate from their dormant state, if this occurs while they are in storage as opposed to once they reach the human gut, the probiotics will be unable to thrive and therefore die, losing the benefit of a live probiotic supplement! While the probiotics have been freeze dried to remove water content, it’s important to choose packaging to prevent water being added during storage. The ability for packaging to allow water ingress is measured using moisture vapour transmission rates (MVTR) of 0 (providing it is well sealed after opening), PET is a poor choice for probiotics packaging, with HDPE a cheaper alternative to glass with an MVTR of 0.5 (Fenster et al., 2019).

Some other important factors to consider include the format of the product. To produce the probiotics into a chewable tablet it must be compressed with force, this pressure can drastically reduce the number of live probiotics, to avoid costly lab trials it might be a better option to consider capsules. Additionally the other ingredients used alongside the probiotic should be considered. If the ingredients have a high moisture content, they will reactivate the probiotic during storage. Similarly the influence of the other ingredients once rehydrated in the stomach may cause the degradation of the probiotics. For example, ingredients with a low pH may cause the stomach acid to kill the live cells, or some natural ingredients may contain antimicrobial compounds such as polyphenols (Fenster et al., 2019). 

Different types?

Once production, ingredients and storage have been investigated now the type of probiotic must be considered, such as Bacillus Coagulans, yeasts like Saccharomyces Boulardii and even ghostbiotics such as para and postbiotics. There are many different types of probiotics each with different attributes. Spore forming bacteria such as Saccharomyces Boulardii are protected by endospores which prevent them from being destroyed by stomach acid before reaching the intestines. Meanwhile, parabiotics are composed of dead cell probiotics. Similarly postbiotics, also called tyndalised probiotics,  contain non-viable probiotics and also the metabolites they have produced. Instead of changing the gut microbiome, parabiotics and postbiotics may have influence on the immune system and inflammation pathways (Siciliano et al., 2021). While ghost-probiotics have different influences on the body, the storage requirements of these supplements are less complicated as there are no living cells to keep alive! 

Cabello-Olmo, M. et al. (2020) “Influence of storage temperature and packaging on bacteria and yeast viability in a plant-based fermented food,” Foods, 9(3), p. 302. Available at: https://doi.org/10.3390/foods9030302.

Fenster, K. et al. (2019) “The production and delivery of probiotics: A review of a practical approach,” Microorganisms, 7(3), p. 83. Available at: https://doi.org/10.3390/microorganisms7030083.

Hills, R. et al. (2019) “Gut microbiome: Profound implications for diet and disease,” Nutrients, 11(7), p. 1613. Available at: https://doi.org/10.3390/nu11071613.

Johnson, K.V.-A. (2020) “Gut microbiome composition and diversity are related to human personality traits,” Human Microbiome Journal, 15, p. 100069. Available at: https://doi.org/10.1016/j.humic.2019.100069.

Kiepś, J. and Dembczyński, R. (2022) “Current trends in the production of probiotic formulations,” Foods, 11(15), p. 2330. Available at: https://doi.org/10.3390/foods11152330.

Mackowiak, P.A. (2013) “Recycling Metchnikoff: Probiotics, the intestinal microbiome and the quest for long life,” Frontiers in Public Health, 1. Available at: https://doi.org/10.3389/fpubh.2013.00052.

Probiotics retailer education White Paper – crnusa.org (no date). Available at: https://www.crnusa.org/sites/default/files/Probiotics/Probiotics%20Retailer%20Education%20White%20Paper%205-13-21%20FINAL.pdf (Accessed: January 15, 2023).

Siciliano, R.A. et al. (2021) “Paraprobiotics: A new perspective for functional foods and nutraceuticals,” Nutrients, 13(4), p. 1225. Available at: https://doi.org/10.3390/nu13041225.

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