In what seems a different life, I worked for a software company in Darmstadt, Germany. If translated literally, Darmstadt means “Intestine Town”; an apt description. The fact that intestine does seem to fit for a description of a miserable town highlights that we don’t think very highly of our internal workings. Whilst it is fine to talk about the mouth and the throat, the further down you go, the more squeamish or embarrassing the conversation seems to become.

Giulia Enders is a remarkable woman: she wrote “Darm mit Charme” having not even finished her PhD at the age of 24. Her enthusiasm for the gut and, more generally, for investigating why things do what they do and what research is available to support the evidence is infectious (in a good way). This comes across immediately. In her few years in academia, she has gained an amazing understanding of the intestines from how food is perceived by the eyes as it enters the mouth to how it is dealt with by our very helpful microorganisms and what is excreted.

She first became a bit of an online sensation when a video of her presentation at the Science Slam in Berlin was posted on YouTube. It talks about the intestines and going to the toilet but with plenty of humour. Whilst it also contains some useful pointers, it is in a way a shame that her fantastic knowledge and enthusiasm has been whittled down to toilet humour. Nevertheless, this humour is a common thread running through the book: if you are going to talk about bums and anuses and farts then you can’t really ignore the associated toilet humour so you might as well roll with it.

Enders covers everything from burping and vomiting to the consistency of poo. However, whilst there are many interesting anecdotes (lie on your left side if you feel you need to burp), the main body of text is regarding the gut flora, the mircobiota that resides in our intestines. Whilst the mircobiota (the community of living organisms sharing our gut with us) only represents 1-3% of our mass, there are 10 times more microbial cells than human cells and it is still startling to many that we are not the only inhabitants of our bodies. There are good and bad microorganisms living at every stage of the gut (as well as pretty much everywhere else on us). Some of the good ones help us to digest complex compounds that our cells cannot absorb, in effect eating our food and providing us with the waste. The bad ones are often tolerated and kept in check rather than attacked, presumably because the energy cost would be too great.

The majority of bacteria are in the large intestine (near the end) whilst in the small intestine we manage the digestion process largely on our own. The opposite is true of cows and other ruminants; they keep most bacteria at the beginning of the digestive system and largely allow the bacteria to do their digesting for them. When the bacteria die, they pass through the intestines and are digested, providing the largest source of protein for the cow. Rodents, on the other hand, keep their bacteria at the end of their intestines and eat their own faeces, as it is a good source of protein in the form of dead bacteria.

Each person’s microbiota is unique. We start in the womb with a clean slate that is then greatly influenced by how we are delivered and how we are fed as babies. By around the age of three, our microbiota has largely stabilised but will continue to change and evolve based on the tactile experiences we have, the choices of food we make and the environment in which we live. This is more the case than ever as we travel more and as food and microbes become global travellers. In one rather odd piece of research in the US, the flora of belly buttons was examined and found to contain bacteria that had previously only ever been found in the seas off Japan.

It is remarkable how new a field of study this is. It only gained serious research attention in the early 1990s and there is still plenty to learn. Enders shares some of the theories with us in a balanced way as if we are part of a research committee. There are, for example, three theories trying to understand what influence our microbiota has on our propensity for obesity. Further theories consider the relationship between us and specific types of microbe. The resounding conclusion that the book comes to is that it is far too early in the research to make any sweeping claims. It is likely that there are multiple causes and bacteria that impact a given symptom and the complexity is just starting to be unravelled. So, if any pharmaceutical company claims to have developed the ‘cure’ for obesity or Alzheimer’s by having identified the bacteria that are causing it or the friendly bacteria that are preventing it, you can only be sure that they are not telling the whole truth.

The final section of the book looks at cleanliness, antibiotics, probiotics and prebiotics. These are words all well covered in the press but mostly misunderstood. One’s stance on cleanliness should neither be to allow your children to endlessly roll in dog-poo-infested mud or to keep them in an airtight, sterilised greenhouse but a sensible balance in between. Most bacteria that we come across are harmless and some are useful so to ban all contact with them is a disadvantage.

Sensible tips she gives are to wash fruit and vegetables; whilst the cleanliness around meat production is tightly regulated, the same is not true of fruit and vegetables that are often fertilised with animal manure that may contain harmful bacteria. Washing them, only with water, dilutes the number of bacteria to proportions manageable by your body.

Enders is not really anti anything but speaks more as a guiding voice to advise when to use one tool and when another. Antibiotics are useful with persistent bacterial infections but are overkill for a common cold (and utterly useless when the cold-like symptoms are from a viral infection).

They can strip both good and bad bacteria from your gut and leave you in a worse position than before. If there is a large population of ‘bad’ bacteria, some may survive an onslaught of antibiotics and those will be the toughest strain, more resistant to future courses of antibiotics.

It would seem that we have underrated our gut in terms of how it affects us but also in terms of its complexity. There are countless organisms living in various stages of our gut and which determine not only what we can and cannot eat but also, possibly, influence our moods and overall sense of wellbeing. It is a deceptively easy read that does not reflect the complexity of the subject matter. Don’t be fooled by the amusing sketches provided by Enders’s sister, this is serious stuff and only the tip of the iceberg. Research will continue and I hope to find further Enders books keeping an amusing tab on the developments.