Researchers Call for Probiotics Long-Term Safety to Be Revised

A woman shops for yogurt, a food commonly associated with good gut bacteria known as probiotics. (Olga Maltseva/AFP/Getty Images)

New scientific evidence shows probiotics’ long-term safety needs to be looked at more closely after the good bacteria were newly assessed by a group of experts in food science, microbiology and other related medical fields.

Their goal was to find out discover how safe probiotics are given that they are increasingly being used not only by patients but by healthy consumers as food and dietary supplements.

Published in the journal Gut Microbes, the new review found that not all uses of probiotics are safe.

“While traditional probiotics have a good safety record based on many published clinical trials and history of safe use, not all uses of probiotics are equally safe," Dr. Mary Ellen Sanders, one of the study authors, told the Medical Express. “Probiotics administered to at-risk populations must be fit-for-purpose, which in some cases requires additional safety scrutiny.”

Prof. Daniel Merenstein, who was the lead author of the study, said that while probiotics have been proven to have efficacy in several indications, there is always a potential for harm, especially after a long-term use.

“Human trials need to do a better job of assessing harm,” he said. “Existing literature demonstrates that probiotics have a very good acute safety record. However, like almost all interventions we use in medicine, the long-term impact is understudied,” Merenstein said.

The 17 experts involved in the review were gathered by the International Scientific Association for Probiotics and Prebiotics (ISAPP) to work especially on the long-term safety of novel probiotics.

Safety Concerns

The scientists stated that one of the long-term safety concerns is the existence of microbial contaminants because the probiotics are in reality, live organisms—microbes— thus, pathogenic contamination here presents a greater risk than for products that have undergone a sterilization process.

Another risk factor is increased exposure to long-term colonizing probiotics. The potential risks here are:

- the probiotic can replace certain microbes that perform important functions.

- the probiotic can impact negatively the function or/and structure of the existing there microbiota;

- if there is a breach of the gut barrier, the probiotic can go through it and cause an invasive infection.

General Recommendations by the Authors

In their article, the authors argued that authorities should be aware of the following recommendations.

1. Probiotic Quality

• Probiotic dietary supplements targeted at vulnerable populations should undergo third-party verification of product quality (purity, potency, and identity), which is accurately communicated on product labels.
• Such products should also undergo testing to meet quality standards appropriate for that population.
• Direct agreements with probiotic manufacturers may be useful for developing products to meet stricter quality control standards.
• Product labels should ideally communicate stricter standards.

2. Adverse Event Reporting

• All clinical trials should rigorously collect and report data on adverse events.
• Events should be listed and defined with reference to standardized criteria where appropriate.
• For each study arm, the absolute risk of each adverse event, using appropriate metrics for recurrent events, and the number of participants withdrawn due to harm should be presented.
• A balanced discussion of the benefits and harms should be presented.

3. Probiotic Product Labelling

• Probiotic product formulations should remove probiotic products that fail to fully identify the probiotic microorganism (genus, species, and strain) and potency through the end of product shelf life.

As the main concern of the scientists is the long-term effect of probiotics use by people, they stated that to achieve this, it is very important to know the genetic makeup of the respective microorganism, which is crucial not only for their strain identification but as well for finding out if they have any genes of concern that can cause toxicity or resistance to antibiotics.

Probiotics VS. Prebiotics VS. Postbiotics

When it comes to gut health, today we hear not only about probiotics but about prebiotics and postbiotics, which can be sometimes rather confusing - what is the difference?

Probiotics

Probiotics are live microorganisms that are beneficial for our health, especially for our digestive system.

They are commonly found in fermented foods such as yogurt, kefir, kimchi, sauerkraut, and kombucha.

Probiotics help to restore the balance of good bacteria in our gut and may offer various health benefits, including:

• Improved digestive health: Probiotics can help to alleviate symptoms of digestive disorders such as irritable bowel syndrome (IBS), inflammatory bowel disease (IBD), and diarrhea.
• Boosted immune system: Probiotics can help to enhance our immune system by producing certain antibodies and stimulating the activity of immune cells.
• Reduced risk of infections: Probiotics can help to prevent and treat various infections such as urinary tract infections, vaginal infections, and respiratory infections.
• Improved mental health: There is evidence that probiotics may help to improve our mental health by reducing symptoms of anxiety and depression.
• Other potential benefits: Probiotics may also have potential benefits for skin health, weight management, and reducing the risk of certain cancers.

Prebiotics

Prebiotics are a type of dietary fibre that is not digested by the human body but serves as food for beneficial bacteria in the gut.

They are found in certain types of plant-based foods, such as onions, garlic, leeks, bananas, and asparagus, as well as in some whole grains and legumes.

When prebiotics reach the colon, they are fermented by the gut microbiota, which produces short-chain fatty acids that have been shown to have several health benefits, including improving gut health, reducing inflammation, and enhancing immune function.

Consuming prebiotics can also help to promote the growth of beneficial bacteria in the gut, such as Bifidobacteria and Lactobacilli. These bacteria play important roles in maintaining the balance of the gut microbiome and protecting against harmful pathogens.

Postbiotics

Postbiotics are bioactive compounds that are produced by the fermentation of probiotic bacteria in the gut.

They are non-viable bacterial components or metabolic byproducts, such as organic acids, enzymes, peptides, and polysaccharides.

Unlike probiotics, which are live microorganisms, postbiotics are not living bacteria, which makes them more stable and easier to use in supplements and functional foods.

Postbiotics have been shown to have several health benefits, including improving gut barrier function, reducing inflammation, and enhancing immune function. They can also have antioxidant properties and may help to prevent certain chronic diseases, such as type 2 diabetes, obesity, and cardiovascular disease.

Some common examples of postbiotics include short-chain fatty acids, which are produced by the fermentation of dietary fibre by gut bacteria.

Probiotics, prebiotics and postbiotics are all beneficial to our gut health, but as described above, they are different in nature and in function.

Prebiotics are the ‘food’ for probiotics, and when probiotics undergo the fermentation process, they produce postbiotics; though different in nature and function, all three of them are needed for our optimal gut health and overall well-being.

It is important to note that the effectiveness of probiotics, prebiotics and postbiotics supplements may vary. Thus, it is essential to consult with a healthcare professional before starting probiotics, prebiotics’ or postbiotic treatments, especially if you have any underlying health conditions or are taking medications.