A brief encyclopaedia of all the health issues the gut can 'cure'
Nature documentaries are fond of pointing out that the deep ocean – not outer space – is the real final frontier of human exploration. It teems with alien life and unexplored depths – and it's right here on Earth.
In many ways the gut is the equivalent of the deep ocean for the human body. The gastrointestinal tract (GI) contains somewhere in the region of 100 trillion micro-organisms, known collectively as the microbiota. Scientists are still plumbing new depths of this mysterious environment, which includes everything from viruses to fungi and bacteria. In the process, they are discovering that while the gut is of course vital for managing digestion, it is also closely linked to brain function and may be a key to boosting many other aspects of our overall health and wellbeing too.
Indeed it feels like not a day goes past without a new study suggesting that the answer to a seemingly unrelated ailment could be found in the gut. Trials begin next month to test whether a strain of bacteria might help with asthma, for example. Meanwhile, earlier this week a team of researchers at Shanghai University reviewed 21 studies covering more than 1,500 people, showing that improving the health of our guts might well help alleviate symptoms of anxiety.
It seems that when it comes to health, it’s good to go with your gut. So what else might a healthy microbiome be able to help with?
According to a study published by Veena Taneja, Ph.D., an immunologist at Mayo Clinic, the microbiome could help diagnose, and possibly play a role in preventing, the joint pain of rheumatoid arthritis. The clinic’s study took a group of rheumatoid arthritis patients, their relatives and a control group who do not suffer from arthritis, and used Genome Sequencing Technology to isolate a biomarker: in other words, find something different about the sufferers that is not found in the control group.
The something they eventually discovered was in the gut flora of patients; they demonstrated an abundance of a rare bacteria, and a microbial imbalance.
In 2014, researchers at University College Cork teamed up with the Irish Rugby Football Union to study 40 elite male rugby players in the run-up to the Rugby World Cup. They compared them against two control groups from the general public with similar BMI, and found that the elite sportsmen had far greater level of gut microbial diversity, showing that eating specific proteins and/or exercising can increase gut health.
Like some other research in the field, the study struggles with a chicken-and-egg problem, in that good exercise might lead to a healthy gut rather than vice versa. Nevertheless, a link is there.
There is only a tentative and partial link drawn between a healthy gut and an improved ability to fight cancer, but one study in 2013 did find anti-cancer treatments may work better on mice when their microbiome is healthy. Scientists at the Gustave Roussy Institute in France found that when bacteria escaped the small intestine, it transformed undeveloped immune cells into tumor targeting T cells.
Studies in this area are ongoing and inconclusive. At Imperial Collegein London, new trials began last month to give a strain of bacteria known as Enterococcus gallinarum to cancer patients in the weeks before surgery, in the hope that when tumours are removed, the bacteria may support the body’s ability to fight the cancer.
Two different types of bacteria are less common in people who report being depressed, according to the findings of a study at Belgian University KU Leuven, which looked at bacteria in the guts of more than 1,000 volunteers. This is a strictly observational study which can’t demonstrate direct causality – the bacteria could be different due to people with depression eating differently, for instance – but it points to a possible link for further exploration.
Researchers have suggested that if the link is causal, it may be due to anti-inflammatory properties in the microbes, because mood disorderscould be caused by inflammation.
Reduced risk of cardiovascular disease
A study conducted by researchers at King’s College London and the University of Nottingham drew on data from more than 600 female twins found on the TwinsUK data registry. It found that high diversity of healthy bacteria in the gut contributed to a lower chance of artery stiffening, suggesting that improving gut health may be a way of preventing cardiovascular diseases.
Scientists at the University of Colorado Boulder ran a study testing the impact of prebiotic fibres – which act as food for good bacteria in the gut – on sleep. They fed two groups of three-week old male rats two separate diets: the first group was given chow containing prebiotic, the second was given standard chow. They then kept tabs on the rats’ sleep cycles and gut bacteria using brain monitoring, and found that the group which tried the probiotic spent more time in good quality, restorative (non-rapid eye movement) sleep.