The Truth About Probiotics.

Introduction.

“Scientific results are always preliminary. No good scientist will believe that they have offered the last word on a given subject. A result is published if the authors and a group of peers consider it a valuable contribution to the field. Crucially, this does not mean it’s correct; it means that it is not obviously wrong.” Professor Brian Cox (2016)

Do you use probiotic supplements? Lots of people take them to counteract the negative effects of antibiotics on our good gut bacteria. Some beekeepers feed them to honey bee colonies, but new research indicates that they are wasting their money for the benefit of the producers and suppliers of probiotics rather than the honey bees.

Antibiotics.

Antibiotics can interfere with our natural gut flora, or microbiome, which comprises trillions of useful but harmless bacteria that are beneficial to digestion, immunity, and many other of our body functions. Bacteria are specific to different parts of the digestive tract and they live in a symbiotic relationship within our bodies. They evolve within our bodies from birth onwards, and one of the first contacts newborn babies have with them is during the birthing process when they come in contact with maternal bacteria. These kickstart the newborn’s own microbiome into action and help with early immunity.

Till I read this, I’d been taking probiotics in capsule form after every course of antibiotics over the recent years.  I’ve not had many courses of antibiotics, never the less, probiotics are expensive and, as I have just discovered, are highly unlikely to make a positive difference.

Honey Bees.

What about probiotics for honey bees? Why use them? Here in the UK, and probably most of Europe, it is illegal to use antibiotics on honey bee colonies because there is zero tolerance for antibiotic residues in honey. The only exception in the UK is when a government bee inspector might prescribe Tetracycline for treating the bacterial infection EFB. This is highly unlikely to happen however as most cases are given shook swarm treatments, or destroyed if severely infected. I couldn’t find probiotics for sale from UK beekeeping suppliers.

In the USA, the situation is different and it is commonplace for commercial beekeepers to give colonies antibiotics to treat bacterial foulbrood infections. Beekeepers understand the damage that repeated doses causes to the good gut bacteria and they attempt to compensate by treating colonies with commercially produced probiotics.

Defining Microbiome.

Before we look at the evidence highlighted by Kirk Anderson in a recent BeeCulture article¹, let’s review the role of the microbiome within the honey bee body. Firstly, as Anderson points out, there is confusion over the words microbiome and probiotics which are often used interchangeably in advertising. This is misleading. This is because the microbiome is a collection of native microbes that co-evolved alongside the host from the beginning. The native microbiome is a key part of the host system. On the other hand, probiotics are non-native bacteria such as genera of Lactobacillus and Bifidobacterium. However,they are not going to harm anyone. After all, humans have been consuming fermented foods over the millennia. In Mongolia they ferment mare’s milk which is a good way to prevent it going “off”. It is also a good way to make an alcoholic drink called airag which is 3% alcohol. For a stronger shot, arkhi is distilled to 12% from the same ingredients. Sounds interesting. I wonder if any of you have tasted airag?

Searching for Evidence.

The problem with probiotics in humans is that non-native microbes are killed off by gastric (stomach) acids, and when they reach the large intestine (colon) the native bacteria don’t tolerate them well so they do not thrive in this environment either. Anderson reports on a meta-analysis which reviewed and reported on all the scientific papers relating to the quality and impact on humans of taking probiotics after a course of antibiotics. His goal was to find evidence that probiotics assisted recovery. He looked at 11,769 studies from 3 data bases but only 20 trials qualified for further analysis under his selection criteria. All the studies showed no real evidence that probiotics aided recovery from antibiotics. There was however, some proof that they are of benefit to humans suffering from irritable bowel syndrome.

I had no idea that the role of the gut microbiome is so extensive and complicated till I started researching for this article. In insects, gut bacteria are involved with their growth, development, metabolism, and reproduction. The gut microbes are also responsible for manufacturing essential nutrients not obtained from food. They increase the efficiency of digestion helping to absorb nutrients and also break down digested foods prior to elimination. Insects generally have fewer microbes than mammals but social insects like honey bees have more opportunities and interactions, such as trophallaxis, to share these microbes. Although insects have an enzyme to help them break down cellulose, having gut microbes makes this process more efficient. Fats, lipids, and proteins are digested by microbes, and detoxification is aided by them too. Insect size, survival, and egg production are all influenced by the microbiome. In 2012, Dr Nancy Moran discovered that some strains of Gilliamella degrade pectin found in pollen cell walls and many other species probably help metabolise carbohydrates.

Moran also found 6-8 core native microbes in the honey bee hindgut. I think it is fascinating that the queen bee has a completely different microbiome from workers despite food sharing. There is so much still to discover about this complicated subject.

Dr Kirk Anderson.

Dr Kirk Anderson is a microbial ecologist at Carl Hayden Bee Research Center, Tuscon, Arizona, and he says that the gut microbiome is not the only bacterial community important to bees. He likens the environment of hive walls to skin and believes that those hive bacteria have evolved to live in one of the most extreme antimicrobial environments given that honey, propolis, and other bee foods have more populations of antimicrobial chemicals than are contained in gut bacteria. From his work, we learn that there are different bacteria in different parts of the gut so that one size doesn’t fit all. This is partly key to understanding why commercial products (at the moment) are not effective. Also, there are 10 genera of bacteria with many different species and they are densest in the hind gut. The most common bacteria in commercial products are lactic acid bacillus but they are just one of 10 required.

I checked out two of the largest US companies supplying honey bee probiotics and searched for their promotional material. I read a Polish paper which the company presented as positive evidence² for using their product. It was a review of the literature around the subject and many studies were scrutinised. I learned a lot and might have been convinced that I should use the product if I hadn’t read through the paper thoroughly. It was such a long paper that I imagine many people might not read right through to the end. If they do, they will learn from the authors that probiotics are non-toxic and safe to use but there is no information yet on how probiotics actually protect honey bees in terms of the molecular mechanisms and how it all works. This sentence resonated with me, “While the importance of gut microbiota is discussed, more often the process responsible for beneficial features of microbial communities remains unclear.” They also make it clear that the protective effects of probiotics against pesticides (particularly neonics) have not been investigated thoroughly.

Field Studies.

What convinced me were the results of very recent research (Anderson et al.2024³) based on field studies rather than lab experiments on caged bees. Colonies were fed monthly doses (for 6 months) of non-native probiotics manufactured by 2 US companies. All the colonies in the study had been given antibiotics before the trial though this was not normal procedure in the commercial apiary where the study took place.  DNA sequencing was used to test whether the non-native bacteria remained in the bee gut. Of 14 million DNA sequences of hind gut bacteria, only 23 of them may have originated from the probiotic treatment. 3 of 7 introduced species were not detected in any worker gut. The other parameters tested were assessing gut microbiota after 6 months and finding no difference between the colonies given probiotics and the control colonies that were not. Applications of either of the 2 commercial probiotics did not hasten recovery of gut microbiome following antibiotic treatments.

Conclusion.

Don’t give up hope though because all this research has dug up so much new information that it should be possible to formulate effective probiotic treatments in the near future. They may also be used to treat the foulbroods and viral infections. Dr Jay Evans has recently studied native bacteria in honey bees in relation to the foulbroods, and finds evidence that they have a role to play in killing Paenibacillus larvae which causes American Foulbrood. So, a bug fight; good bugs knock out bad bugs. Also, natural native bacteria can prime the immune system so may be able to be further developed in the treatment of bacterial and viral infections though Evans points out that, “you don’t want an immune response raging all the time”.

References.

¹https://www.beeculture.com/the-hopeful-state-of-probiotic-science/

²Anderson KE, Allen NO, Copeland DC, Kortenkamp OL, Erickson R, Mott BM, Oliver R. A longitudinal field study of commercial honey bees shows that non-native probiotics do not rescue antibiotic treatment, and are generally not beneficial. Sci Rep. 2024 Jan 23;14(1):1954. doi: 10.1038/s41598-024-52118-z. PMID: 38263184; PMCID: PMC10806037.

³Nowak, A.; Szczuka, D.; Górczynska, A.; Motyl, I.; Kregiel, D. Characterization of Apis mellifera Gastrointestinal Microbiota and Lactic Acid Bacteria for Honeybee Protection—A Review. Cells 2021, 10, 701. https://doi.org/10.3390/cells 10030701