Probiotics contain microorganisms, usually bacteria. These products are available as food supplements and are sometimes added to food. Probiotics are believed to enhance gastrointestinal health and prevent allergies.
Business is booming
Germans are big fans of probiotics, which are among the best-selling food supplements. Nearly six million packages were sold in pharmacies alone in 2019. Compared to 2018, revenue from probiotics increased by €11 million to a total of €160 million (Kannamüller 2020). Probiotic food supplements are also flying off the shelves in drug stores and supermarkets.
But as far as allergies are concerned, scientists remain sceptical about probiotics. “Probiotics are a lifestyle treatment”, says Britta Siegmund, specialist in gastroenterology at Charité in Berlin (Kuroczik 2019). One reason for this cautious attitude is because different studies have reached different conclusions.
Need for standardised studies
Allergies are common to begin with. Nearly one in ten newborns will go on to develop at least one allergy during his or her lifetime. The allergy risk is even two to three times higher for those whose family members already have allergies (Cuello-Garcia 2016).
This is why researchers are focused on finding preventive measures, and a number of studies on probiotics and allergies have been conducted. However, the results of the studies so far have not yet convinced the medical associations. The reason for this is because the individual studies are difficult to compare. Different preparations were tested. There were also differences as to when they were administered and for how long, and some of the studies included so few mothers and/or babies that the results from them cannot be extrapolated.
A study presented at the European Allergy Congress EAACI 2020 (Bergmann 2020) shows how standards could be introduced. It tested the influence of probiotics under precisely defined and repeatable conditions in the ECARF pollen chamber. The result was a reduction of allergy symptoms in people with birch pollen allergy.
Recommendation of professional associations
Medical associations are very cautious in their recommendations because it is not yet clear whether probiotics are effective. There are indeed studies demonstrating that the preparations have a positive effect (e.g. Lodinová-Zádníková Int Arch Allergy Immunol 2003 and 2010). But in other studies, probiotics failed to reduce allergies (e.g. Wickens 2018).
So the current recommendation is that women who are pregnant or nursing and newborns do not need to take probiotics (Wang 2019).
The World Allergy Organization (WAO) makes an exception for newborns whose family already has a history of allergies. These at-risk children could benefit from probiotic formula (Cuello-Garcia 2016).
Allergy risk depends on many factors
In terms of allergy prevention, it is necessary to think beyond probiotics, since there are a number of factors that promote allergies. These include (Aitoro 2017):
- Caesarean section
- Frequent use of disinfectants
- Use of antibiotics and antacids
- Excessive consumption of fatty foods (junk food)
Breastfeeding babies and subsequently feeding them a healthy diet can go a long way to helping prevent allergies. A healthy diet includes dairy products, fish, fibre, vegetables and fruit. Fermented foods such as sauerkraut or kimchi, a Korean dish made of pickled Chinese cabbage, also promote gut health.
Human microbiome is a black box
Nearly 2,000 years ago, Hippocrates already knew that “all diseases begin in the gut.” Researchers are now certain that this statement from the most famous doctor of the ancient world more holds than an ounce of truth (Lyon 2018). But research into how microorganisms influence the immune system is still in its infancy.
There are about as many microorganisms on and in the body as there are human cells. They are found on the skin and mucous membranes and even in our internal organs. Most microorganisms live in the gut. All microorganisms as a whole are referred to as the microbiome. The microbiome plays an important role in defending the body against pathogens. If there are not enough microorganisms, or they are not present in the right amounts, illness can result.
There seems to be no single optimal microbiome. “Each individual has their own highly individual ‘bacterial profile’ at birth and in the initial months of life. Researchers compare it to the human fingerprint in terms of how difficult it is to change”, explains Angela Sommer from the editorial office of Quarks, the science programme of Westdeutscher Rundfunk in Cologne (Sommer 2019).
This makes it difficult for scientists to identify which microorganisms cause disease and what can be done to prevent it. Rosita Aitoro of the University of Naples Federico II and her team believe that short-chain fatty acids in the gut microbiome play an essential role. These metabolites strengthen the immune system, which probably also prevents allergies (Aitoro 2017).
The microbiome continues to be an exciting research field. Once we have a better understanding, the importance of probiotics could change. If the products contain the right microorganisms in sufficient quantities, they could be considered an effective means of preventing and treating allergies.
Image source: Bru-nO, Pixabay 2018
Last updated: 30 June 2020
Lodinová-Zádníková R et al. Oral Administration of Probiotic Escherichia coli after Birth Reduces Frequency of Allergies and Repeated Infections Later in Life (after 10 and 20 Years). Int Arch Allergy Immunol. 2003;131(3):209-11.