Study hints at power of gut bacteria to protect against cancer

Several studies have suggested that bacteria in the gut could be used to reduce the risk of certain types of cancer.

Now a study published in PLOS ONE has strengthened the evidence that ‘good bacteria’ can slow or stop the development of lymphoma — in mice at least.

The typical human body is about 50 per cent bacteria, most of which are in the gut. Some of these bacteria are ‘good’ in the sense that they reduce inflammation, and some are ‘bad’ because they promote inflammation. Chronic inflammation is now believed to play an important part in the development of many diseases, including cancer, heart disease and arthritis.

Robert Schiestl, professor of pathology at UCLA, said: ‘Doctors might be able to reduce a person’s risk for cancer by analysing the levels and types of intestinal bacteria in the body, and then prescribing probiotics to replace or bolster the amount of bacteria with anti-inflammatory properties.

‘It is not invasive and rather easy to do.’

Previous research has shown how bacteria called Lactobacillus johnsonii 456, the most abundant of the body’s ‘good’ bacteria, might delay the onset of cancer, and that probiotic supplements might even prevent it from forming in the first place.

In a paper published by Cancer Research Schiestl and his team studied mice with genetic mutations that made them susceptible to lymphoma and other cancers. The mice were divided into two groups. One group was given only anti-inflammatory bacteria and the other received a mix of inflammatory and anti-inflammatory microbes.

Schiestl and his team showed that in the mice with more of the beneficial bacteria, the lymphomas took twice as long to form. The ‘good’ bacteria group also lived four times longer and had less DNA damage and inflammation.

For the latest paper, Schiestl and colleagues analysed metabolites — chemical substances produced by bacteria in the intestine. The mice that received only the ‘good’ bacteria produced metabolites that are known to prevent cancer. These mice were also better able to metabolise fats, which researchers think may lower the risk of cancer.

Schiestl said: ‘Together, these findings lend credence to the notion that manipulating microbial composition could be used as an effective strategy to prevent or alleviate cancer susceptibility.

‘Remarkably, our findings suggest that composition of the gut microbiota influence and alter central carbon metabolism in a genotype-independent manner.

‘In the future, it is our hope that the use of probiotics would be a potential way to prevent cancer in normal humans, while the same type of microbiota would decrease tumour incidence in cancer susceptible populations.’

Instant analysis
Knowledge of the gut microbiome is growing at an exponential rate. The impact its changes have on human health is slowly becoming clear and has been demonstrated in a number of conditions, among them obesity and certain cancers.

This prospective animal-based lab study looked at the metabolic effects of changes in the gut microbiome.

Researchers altered the mice’s gut bacteria and then, due to the metabolic changes they found, observed a decreased incidence of cancer. This is extremely promising.

It may be possible to alter human susceptibility to cancer via metabolic manipulation — that is, by understanding and altering the vast ecosystem living in the human gastrointestinal system.

This is preliminary work, and requires confirmation in both animal and human subjects, but is still a significant finding. TSA
Research score: 4/5