Eating too many burgers, chips and pizzas is causing an increase in bowel cancer deaths among younger people, according to new research. More middle aged people are dying from the disease than ever before – despite cancer mortality rates dropping overall. Scientists have described the phenomenon as a “frightening anomaly” – and blamed it on the consumption of high fat foods. The study found they fuel tumours by upsetting the balance of bile acids in the intestine.
This triggers hormones that let potentially cancerous cells thrive.
And the discovery has led to the development of a drug that could stop the process.
It offers hope of curing a disease that kills more than 16,000 people annually in the UK.
The findings published in Cell may explain why it is being seen more commonly in the ‘junk food generation’.
Professor Ronald Evans, a biologist at the Salk Institute, La Jolla, California, said: “This study provides a new way to lower inflammation, restore intestinal health and to dramatically reduce tumour progression.”
Experiments in mice suggest lifestyle and genetics combine to cause the disease.
Those with a mutation called APC, the most common in patients, developed a tumour faster when fed a high fat diet.
The intestine and colon, commonly called the ‘gut’, are hard-working organs.
As you eat, they need to constantly regenerate the lining to undo the damage done by digestive acids.
To do this, the gut houses a population of stem cells that can replenish the lining when needed.
Bowel cancer often originates from mutations in these stem cells.
The APC gene normally acts as a ‘tumour suppressor’, controlling how often cells divide. Variants can lead to cells dividing rapidly instead, and becoming cancerous.
Prof Evans’ lab has investigated the roles of bile acids for four decades.
There are 30 types types that float around in the gut to help digest food and absorb cholesterol, fats and fat-soluble nutrients.
His team has shown they send hormonal signals to intestinal stem cells through a protein called the FXR (Farnesoid X receptor). They have now uncovered how high-fat diets affect that hormonal signalling.
First author Dr Ting Fu found bile acids known to interact with FXR increased at the same time as cancer initiation in mice with a mutated APC gen. Additional acids accelerated cancer progression.
Co corresponding author Dr Michael Downes said: “We saw a very dramatic increase in cancer growth correlated to bile acid.
“Our experiments showed maintaining a balance of bile acids is key to reducing cancer growth.”
Feeding the mice a high-fat diet was like adding fuel to a fire. It increased levels of two specific bile acids that dampen the activity of FXR.
The gut wants to repair itself, and FXR keeps the process slow, steady and safe. When bile acids inhibit FXR, a group of stem cells starts growing rapidly and accumulating DNA damage.
Prof Evans said: “While colon cancer is considered ‘incurable,’ Ting’s work opens up an entirely new frontier in the understanding and treatment of the disease.”
Bowel cancer symptoms are not always easy to spot as they can be mistaken for less serious health conditions.
Many of the signs are linked to changes in bowel habit, but there are four symptoms in particular you should check for when you go to the toilet.