A cure for irritable bowel syndrome (IBS) could be in the pipeline following the results of a groundbreaking new trial.
Scientists believe they have been able to pinpoint exactly why women are up to twice as likely to suffer the lifelong digestive condition.
Previous research has suggested the female sex hormone oestrogen may be to blame by smoothing muscle cells that line the walls of the stomach and intestines contracting — slowing down the movement of food and waste through the body.
Now US researchers have found that oestrogen receptors — proteins found in cells that boost oestrogen — were clustered in the lower part of the colon.
These helped specific cells, known medically as L-cells, to release the hormone PYY, which activated painful nerve fibres.
In tests on mice, the scientists from the University of California, San Francisco, then blocked oestrogen and PYY and discovered, gut pain among females ‘dramatically reduced’.
Dr Holly Ingraham, a professor of molecular and cellular pharmacology at the University of California, San Francisco and study co-author, said: ‘Instead of just saying young women suffer from IBS, we wanted rigorous science explaining why.
‘We’ve answered that question, and in the process identified new potential drug targets.’
Dr Eric Figueroa, an expert in pharmacology and physiology at the University of California, San Francisco, added: ‘PYY had never been directly described as a pain signal in the past.
‘Establishing this new role for PYY in gut pain reframes our thinking about this hormone and its local effects in the colon.’
Current NHS guidance for managing IBS includes the low-FODMAP diet, which involves removing high-FODMAP foods.
FODMAP stands for fermentable oligosaccharides, disaccharides, monosaccharides, and polyols.
Common foods with gas-producing FODMAPs include broccoli, beans and lentils, wheat, garlic, onions, apples, and some fruit juices.
But, writing in the journal Science, the US researchers said that their observation may also explain why low-FODMAP diets help some IBS patients.
Eating fewer FODMAPs may prevent L-cells from churning out more of the pain signalling PYY, they added.
‘Even for patients who see success with a low-FODMAP diet, it’s nearly impossible to stick to long term,’ Dr Ingraham said.
‘But the pathways we’ve identified here might be leveraged as new drug targets.’
When the researchers gave male mice oestrogen to mimic the levels found in females, their gut pain sensitivity increased to match that of females.
It’s estimated one in five UK adults have IBS but as many don’t seek medical advice experts say this could be an underestimation.
Most commonly it affects young people between 20 and 39 and is less prevalent in older age groups.
Symptoms which are often better some days and worse during flare-ups include stomach pain, bloating, diarrhoea and constipation.
Passing mucus in stool, fatigue, nausea, backpain, not being able to control when you pass stool and problems urinating can also be experienced by those with IBS.
