2.3 Metabolism of drugs and xenobiotic chemicals
Another important function of the gut microbiome is the metabolism of some chemicals which are foreign to the human body. Such substances are known as xenobiotics.
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Question 8
Every human is exposed to some xenobiotic chemicals during their lifetime. From your general knowledge, think of some categories of xenobiotics you may have come across before.
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Some of the categories of xenobiotic chemicals you may have thought of include food additives, such as flavourings and colourings, pesticides, cosmetics, and fragrances. You might also have considered drugs (both medicinal and recreational), industrial chemicals and environmental pollutants.
As well as producing enzymes that are important for digesting components of the food eaten by the human host, the gut microbiome also manufactures enzymes which can break down some xenobiotic chemicals (Zhoa, 2023).
It has long been known that the human host genetics, age, sex assigned at birth, lifestyle, metabolism, disease status, other medications and environmental factors can all affect how different individuals respond to medications. This is termed individual variability in drug response (IVDR). However, recent research has shown that the gut microbiome of the individual also plays an important role in the IVDR. This new area of research has been called pharmacomicrobiomics.
As you will learn shortly, the gut microbiome can be modified (both beneficially and detrimentally) in many ways. This can potentially alter the way an individual will respond to a medication, for example, changing drug efficacy and therapeutic effects. So, this modification of the microbiome is potentially an important new way that drugs can be made more effective in an individual, or have fewer side effects and interactions with other medications.
The Human Microbiome Project (HMP) in collaboration with the National Institutes of Health (NIH) are investigating the diversity and function of the human gut microbiome (much like the Human Genome Project), to identify its impact on health human and IVDR (HMPDACC, n.d.).