Myth busting: Probiotics and immunity

How do probiotics and prebiotics really help support our immune function?

Components of the immune system can be split into the innate or natural system, and the adaptive or acquired system. The innate immune system encompasses what is commonly described as an individual’s ‘first line of defence’ i.e. physical barriers that prevent undesirable foreign substances such as micro-organisms, allergens or toxins from entering the body.

In this respect, probiotics help to strengthen the body against pathogens through improved gut barrier function that stops harmful micro-organisms from entering the blood stream. This also results in improved microbiome diversity which serves as a natural defence against pathogens getting to uncontrollable levels in the gut.

Some white blood cells operate in the innate immune system and are “hard-wired” to respond to particular molecular warning signals. Some probiotics have the ability to support the function of these white blood cells in the body. These cells play a critical role in many protective processes, such as ingesting foreign bacteria, cell debris as well as dead or damaged cells. Some of these white blood cells also contribute to co-ordinated immune responses to infections and other threats to the body.

NZMP’s Lacticaseibacillus rhamnosus HN001 (LactoB HN001, formerly known as Lactobacillus rhamnosus HN001) and Bifidobacterium animalis sbsp. lactis HN019 (BifidoB HN019) strains, for instance, have proven positive impacts on the immune system throughout the human life stages. Evidence shows that they can support or enhance various features of the immune system, including interacting with the lymphoid tissue of the gut epithelial layer and supporting the function of innate white blood cells.

Research has also shown that prebiotics may help to support immunity, digestive health and gut comfort, which is particularly important for vulnerable consumer groups such as infants. Galacto-oligosaccharides (GOS), a type of prebiotic derived from the lactose in cow’s milk, are not digested in the upper part of the gastrointestinal tract and can reach the large intestine where they positively stimulate the growth of beneficial bacteria, such as Bifidobacteria. These bacteria can produce short-chain fatty acids and other metabolites, which stimulate immune health and promote digestive health to support gut comfort. GOS has also been shown to improve the absorption of minerals in the intestine.

And how can fermented food and drink also do this?

During the fermentation process, microorganisms such as bacteria and yeast convert organic compounds – such as sugars and starch – into alcohol or acids. 

However, it’s important to note that while fermented foods and beverages may have microbes in their production process, they are not necessarily probiotic. The World Health Organization defines probiotics as “live microorganisms which when administered in adequate amounts confer a health benefit on the host”. In order to be labelled a probiotic, scientific evidence for the health benefit would have to be documented.

Likewise, the ability of microbes in fermented foods to support immune health needs to be backed by clinically documented evidence. Additionally, even if microbial cultures used for fermentation include probiotics, final manufacturing steps such as baking or pasteurisation at times can kill these probiotics.

Are there any specific formats that consumers should look for when they’re searching for products that can provide a genuine immunity benefit?

Overall, the format of a probiotic does not appear to impact the health benefits it provides. However, it is important that the product is stored appropriately and consumed in a way that does not impact the integrity of the probiotic. Consumers should also avoid products that require heating before consumption, as most probiotics are sensitive to heat and will die. To be considered a probiotic, the beneficial microbe must reach the gut alive.

One thing consumers should be mindful of when searching for products is the dosage of probiotic, which is labelled as a Colony Forming Unit (CFU) per serve. To provide consumers with the desired health benefit, a probiotic strain needs to be at a CFU equal to or higher than the dose used in successful human clinical studies. However, a higher dosage does not necessarily equate to a greater health benefit.

Classic fermented dairy products such as yoghurt and natural cheese are also good vehicles for probiotics, especially when stored chilled. However, challenges emerge for products where heat and moisture are both outside the normal comfort zone for a probiotic, such as liquids or moist environments at room temperature, or products that require excessive heat during processing. Nonetheless, there are some exciting innovations currently being developed as we look for ways to overcome hurdles to product stability. For instance, our strains have shown very good stability in chocolate.

Conversely, there is a type of probiotic on the market that is very robust and can withstand high heat for long periods. These are spore-forming probiotics. However, these stability qualities of spore-forming bacteria can create challenges for manufacturers as they are extremely difficult to remove from the manufacturing environment and inevitably result in the contamination of manufacturing plants. This has been a real quality concern for some of our customers who subsequently steer away from spore-forming probiotics.

How can consumers decipher for themselves whether fermented food and drink products contain the live bacteria that provide the health benefits they’re after?

When searching for immune-boosting products, consumers need to be aware that there is a wide range of probiotics available in the market and each strain will provide a different set of health benefits. However, understanding the science behind probiotics can be a complex business and they should approach medical professionals for a recommendation on the strain, dosage and duration of treatment based on their needs. But some general pointers they can consider include:

• Select products according to the needed health benefit: Probiotics are not a magic solution to cure all ailments. Not all probiotics will provide the same benefits and consumers should choose a strain that has been clinically proven to address specific health concerns.

• Dosage: The amount of probiotics in a product will be labelled as CFU per serve. A probiotic strain needs to be at a CFU equal or higher than the dose used in successful human clinical studies to provide consumers with the health benefit. However, it is also important to note that a higher CFU does not necessarily mean extra health benefits.

• Shelf life: Look for products that guarantee CFU throughout the shelf life. This is because probiotics can begin to die in the time frame between the product being manufactured and consumed by the end-user. If all the probiotics are dead, or the dose is below the recommended level, consumers may not achieve the health benefit they are looking for. For instance, products with disclaimers such as "X CFU per serving at the time of manufacture" often means they have not been tested to guarantee that the CFU stated on the pack truly reflects the minimum amount of probiotics still alive by the product's use-by or expiry date.

• Storage: Some probiotics will need special storage conditions to remain alive so consumers will need to check the storage instructions on the product. If the retailer is not adhering to these instructions, the probiotics may not be alive.

• Avoid products that need to be heated before consumption as most probiotics will be killed at high temperatures.

• In addition, one of the most important considerations is for consumers to consistently take their probiotic of choice. This is because regular consumption is required to maintain a certain probiotic's level in the gut, in order to realise the desired health benefit. If consumers stop taking a probiotic, then their gut bacteria will normally return to the same state they were in prior to supplementation within a couple of weeks. The health benefits will usually subside as well, although some types of probiotics have been selected specifically because they linger in the gut.

The global dairy co-operative Fonterra is working to create some clarity on the subject of probiotics and immunity with its online whitepaper.