The emerging field of personalised medicine seeks to tailor therapies to suit an individual’s metabolism or genetic make-up. This strategy has worked well with medication for specific forms of breast cancer and more generally with drugs which are metabolised by liver enzymes, such as the immunosuppressant thiopurines for inflammatory bowel disease.

We’re now beginning to realise that a personalised approach to medicine can help improve the health of your gut in many ways.

Good vs bad bacteria

Your lower gut is home to a phenomenal number of bacteria made up of so-called good strains and bad strains. The good bacteria help your immune system develop, salvage nutrients and keep the bad bacteria in check. For their part, the bad strains are associated with bowel cancer, inflammatory bowel disease and a host of other conditions such as obesity.

Eating live cultures of the good strains may help with common gut complaints such as bloating. But live cultures don’t survive long in the upper intestine – most are gone within 48 hours. Even those bacteria protected within a pill are unlikely to gain a foothold in the already thriving ecology of your lower intestine.

Until recently, it wasn’t even clear what kinds of bacteria were present in your lower bowel, much less the relative numbers of each.

Now, new genetic testing in mice has shown we may be able to identify thousands of different strains of bacteria in the human gut – work that is now underway. This would allow us to map our individual bacterial community and better understand the role particular bacteria play in producing (or reducing) common gastrointestinal complaints.

Investigations

The best way to find out what’s happening inside your gut is to have a look. And there’s nothing more personal than taking a few pictures along the way. This generally involves an endoscope – a camera attached to several metres of fibre optics – which is gently fed down your oesophagus and to regions below.

Endoscopy (or colonoscopy) is the most common (and unfortunately priciest) outpatient procedure at most hospitals. One reason for the expense is that it takes a highly skilled clinician to safely perform these procedures. A slip while taking pictures can tear the gut wall which, if left untreated, can cause the bacterial community to move into your abdomen’s peritoneal cavity.

With the advent of cheap digital cameras, many companies have tried to place a tiny camera inside a pill. This development is important, as colonoscopy-based bowel cancer screening programs dramatically increase the number of expensive procedures. Thus a cheaper and more efficient alternative is needed.

Once swallowed, the pill-cam travels down the entire gastrointestinal tract along with any other food. Until recently, a special harness was needed to help communicate with the camera and track its position in the gut. Even then, only a few pictures could be taken on the way through – often missing important but small features that can lead to incorrect diagnoses.

Imagine driving a car and looking for a particular small lane way. Traffic is busy and it’s impossible to get more than a glimpse out of the window. Now imagine you are using the Google street view camera – you have a continuous, wide angle shot of the whole street that you can review at home. This is what the recently released CapsoVision does. The capsule makes a scrapbook of images from your entire gastrointestinal tract which reduces the guesswork in diagnosing problems.

Researchers are hoping that in future, these capsules will be paired with computerised diagnoses systems to analyse all these images and help the clinician plan your personalised treatment.

Next steps for therapies

While bowel cancer can potentially shorten your life expectancy, many other diseases of the gastrointestinal tract are life-long and come with a variety of unpleasant symptoms. Common gastrointestinal diseases – such as inflammatory bowel disease (IBD), irritable bowel syndrome (IBS) or even obesity (which is associated with pain, reflux and diarrhoea) – are ripe for a personalised approach.

For IBD, the front-line class of drug called thiopurines is metabolised by several families of liver enzymes. For some people, genetic variation in these enzymes can greatly affect the levels of thiopurines that are available to help reduce the inflammation in the gut.

There are many important hormones in the gut which regulate gastrointestinal function as well as alter how you feel, such as being satisfied after a meal. Serotonin, a gut hormone that helps keep your meal moving, is particularly important in this process and has been the target of several classes of drug designed to reduce the symptoms of IBS, constipation, slowed gastric emptying and reflux.

Given that the levels of serotonin in your gut can determine whether some therapies are effective or not suggests another area that could benefit from a personalised approach, perhaps by characterising the levels of all gastrointestinal hormones and their receptors.

Technology is driving many of the advances in personalised medicine and is allowing for the variation in individuals to be taken into account during treatment.

Patients struggling with unpleasant and debilitating gastrointestinal diseases may benefit from some of these advances today such as the pill-cam or your drug metabolism profile; while cataloguing your microbial community or your gut’s hormonal control system will take five to ten years before applications appear in the clinic.