Q&A: Enterotypes, Butyrate, and washing up liquid and our gut

Welcome to the second of our weekly Q&As! The first question (can we change our enterotype?) is available to all subscribers (don’t worry - we cover what an enterotype is and why it may be important). There are further questions behind the paywall (about short chain fatty acids such as butyrate and about the effect of washing up liquid on our gut).

If you have any questions that you would like to be answered in future weeks, please do submit them here.

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Q. A recent article identified three different bacteria species that predominate in the gut, with type B (Bacteroides) being the best at nutrient extraction as well as the fastest to process. Is there a way to affect the microbiome in a way to encourage the type B population over types P and R?

• Older, aspiring to be wiser

A. To answer your question we need to dive into the science of the microbiome! Differences in diet, exposure to medications and other factors all alter the makeup of our gut microbiome. People with very different lifestyles will have very different gut microbiomes. Over the last 2 decades, there has been mounting evidence that these differences in microbiome can be classified into three distinct groups or enterotypes, with the dominant bacteria in each defining the cluster. 

The three main enterotypes are defined by the dominant genus of bacteria in them and are P (prevotella), B (bacteroides) and R (ruminococcus). The P cluster is associated with long term consumption of whole grain whole foods, like vegetables, grains and fruit, as well as refined sugars in puddings and sweets. The B cluster occurs with meat and fat heavy diets, as well as with consumption of refined sugars. It is linked to a “Western diet” and often associated with poor microbial diversity. The R cluster is associated with rural diets that are rich in plant based food and very high in fibre. 

Why is the enterotype important? At the moment enterotypes are mainly useful because they help us to group people for research, so that those with similar microbiome signatures can be studied together. This helps us to understand what these signatures mean. Not everyone is convinced however, that enterotypes exist, and believe that it is more of a “sliding scale” between groups.

Enterotypes may be more useful in the future, as they may help us personalise the use of diet types, exercise plans and medicines to optimise and personalise our care - but we are definitely not at this point yet. Here are a couple of things that we do know already: increased P/B ratio is associated with obesity. People with a P predominant enterotype are more likely to lose weight on a high fibre diet than those with a B predominant enterotype. A study has shown that the B enterotype is associated with greater nutrient extraction from our food. But whilst this may have been an advantage in the times when food was scarce, it may not be an advantage now. The subjects in the study who had the B enterotype, and who extracted more energy from their food, were also found to be overweight and had reduced gut microbiome diversity. 

So there’s not yet enough evidence to recommend trying to shift from one enterotype to another. Indeed, I probably wouldn’t want to aim for a B enterotype given the mixed study results. In addition, microbial diversity may be more important than your enterotype in any case. A study (from The Center For Happiness Studies in Seoul) comparing emotional well-being scores based on enterotypes found that your happiness is not associated with your enterotype, but for those with P enterotype, happiness does correlate with increasing microbiome diversity.

What influences enterotype? I’ll start with the things that don’t influence it (because they’re a bit surprising): it’s not affected by age, gender, or BMI. It is strongly affected by long term diet and can alter with medication as well, in particular antibiotics. And it seems that it is long term diet, rather than short term changes, that affect our enterotype. So if we did have more evidence in the future that switching between enterotypes was beneficial, it might be possible to do so.