Look After Your Microbiome and It Will Look After You!
Having just received the results of a gut microbiome test I submitted, this has made me particularly conscious of how readily microbiome composition can change depending on the foods it is exposed to. Mine is actually not too bad but there is room for improvement!
However, the microbiome is not only influenced by diet but also by exposure to environmental chemicals, so a recent Review of how the chemicals we are exposed to can affect the microbiome caught my attention.
Why Does This Matter?
Because mounting evidence indicates that the composition and functioning of the microbiome is profoundly linked to human health and disease.
The effects of the microbiome extend well beyond the gut to other organs such as liver, brain, bones and muscles. In fact, we can now consider the microbiome to be a new organ in the body and it is crucial that it functions properly. However, the microbiome can be influenced by many internal and external factors.
Environmental toxins and chemicals can lead to microbiome changes which affect how it functions. Many chemicals have been tested for toxicity - however, the effect on the microbiome is not considered so the toxicity of certain chemicals may be underestimated.
Some chemicals may directly affect the actual microbes in the gut and others may affect the gut environment - the lining of the gut (mucosa) and the communication which occurs between gut microbes.
External factors affecting the microbiome include:
- Antibiotics and other drugs These can severely reduce gut bacterial populations which can recover to some extent although often result in imbalance and reduced diversity. Other drugs which affect the microbiome include Non-Steroidal Anti-Inflammatories (eg ibuprofen), proton pump inhibitors (eg omeprazole, Nexium) metformin, some antipsychotics. A recent study tested 1200 different drugs to investigate their effect on the microbiome. A quarter of human-targeted drugs were found to have effects on gut bacteria to some degree.
- Heavy metals Gut bacteria can actually be helpful with changing some heavy metals such as arsenic into less toxic forms, although the opposite can happen with heavy metals too. Metals such as mercury cadmium, cobalt, lead can cause changes to the way microbes function and negatively affect the substances they produce.
- Pesticides We are told that pesticides are safe because the way they work does not affect the human body. However this has failed to consider the effects on the human microbiome. For example, the target of the herbicide glyphosate (in your Roundup weedkiller!), known as the shikimate pathway, is actually present in human gut bacteria and chronic low-level exposure to glyphosate has been implicated in some cancers and other diseases. In 2015 the World Health Organisation reclassified glyphosate as "probably carcinogenic" to humans (although you will still find Roundup for sale in the UK!) Several studies in animals have demonstrated the toxic effects of pesticides on the gut microbiome. The insecticide Diazon has been shown to affect the gut microbiome of mice - affecting the bacterial production of neurotransmitters, this may partially be responsible for its neurotoxic effects.
- Artificial Additives Food additives such as artificial sweeteners, emulsifiers and preservatives are added to food products with an approved safe amount. However, when these standards were determined gut microbiome toxicity was not considered. Several studies have demonstrated that food additives cause changes in composition and function of the microbiome with potential health consequences. For example, saccharin consumption may influence the microbiota leading to glucose intolerance. Acesulfame potassium, sucralose and aspartame have been implicated in microbiota changes contributing to obesity and inflammation. Two commonly used emulsifiers, CMC and polysorbate-80 have been shown to alter gut microbial composition leading to increased gut inflammation.
These are just a few examples of substances we are exposed to which may affect the microbiome. A rapidly-growing list of xenobiotics (chemicals foreign to living things) is linked to gut microbiome toxicity and this toxicity is a link between the environment and human diseases.
Reduction in diversity has been linked to many diseases. We need our microbiomes to be diverse in species in order to be resilient and function well.
Exposure to environmental chemicals such as antibiotics, artificial food additives and heavy metals may be reducing microbiota species richness and diversity leading to dysfunction in the gut. These chemical induced changes may be contributing to gut dysfunction and consequently to a range of human diseases.
What Can We Do?
Some environmental exposures we cannot easily avoid. However, having the knowledge of how they can affect the microbiome, and potentially our heath, should help us to make decisions about the foods we eat (reduce artificial additive intake), cleaning products we use in the house, pesticides/herbicides we use in our gardens.
There are now many natural products available which not only are better environmentally but are also kinder to our microbiome!
If you are interested in testing the status of your microbiome please get in touch for more information.
Tu, P.; Chi, L.; Bodnar, W.; Zhang, Z.; Gao, B.; Bian, X.; Stewart, J.; Fry, R.; Lu, K. Gut Microbiome Toxicity: Connecting the Environment and Gut Microbiome-Associated Diseases. Toxics 2020, 8, 19.