‘My stomach’s upset; it must be something I’ve eaten!’  That’s the obvious conclusion.  After all, food intolerance is very common.  Forty-five per cent of people in the UK claim to be allergic or intolerant to food, according to Lindsay McManus, information manager at Allergy UK.  Yet clinical evidence of an allergy or biochemical intolerance to food is only found in about 5% of people tested. 


So what is going on?  Professor Ian Rowland, Head of the Hugh Sinclair Unit of Human Nutrition at Reading University, believes that although people attribute gut upsets to the food they’ve eaten, most cases of food intolerance are related to psychological factors causing a greater awareness of gut function.  People with unexplained gut symptoms tend to have an abnormally sensitive gut.  When balloons are inflated in the rectum, the intestine and even the oesophagus, they feel discomfort at lower volumes.  Just as  putting on your top is painful if you have been sunbathing for too long,  so the sensitive gut ‘feels’ the food  that goes through it.  And it reacts by going into spasm or adopting a posture of rejection, which may result in diarrhoea or vomiting.   


What might cause the gut to become sensitive?  Stressful life events are clearly implicated, but a previous infection can also sensitise the gut.  About 10% of  people develop Irritable Bowel Syndrome (IBS) after an attack of food poisoning – even though the infection clears up after a few days.  Research conducted in my laboratory several years ago demonstrated that those that developed IBS had more anxiety, more depression and more traumatic life events at the time of the original infection than the remainder whose illness had completely resolved.  It was as if the symptoms of gastroenteritis had been recruited to express the ongoing situation and would only disappear when that had been resolved.  A persistent connection between mind and gut is much more likely if the food intolerance has been caused by a particularly traumatic event.    



Amanda was excited when Rick invited her out. He said he had something to say to her.  She felt sure he was going to propose at last.  The venue was perfect; a little fish restaurant in the next village. Rick was attentive as usual but seemed tense.  They chose the wild salmon with prawns and Hollandaise sauce and shared a bottle of sauvignon blanc. She had just finished hers when he told her.  He had been seeing Margaret, who worked in the office – and well – somehow Margaret had got pregnant. Amanda listened with mounting horror. How could this be happening? Suddenly she couldn’t sit there any more. She rushed through the restaurant to the ‘ladies’ where she was seized with the most violent spasms of retching. She didn’t stop vomiting for three days. That was three years ago. Amanda took a job in another town. She has been out a few times with other men, but always feels sick.  She has become intolerant of fish.   Even the smell of fish makes her ill. Other foods seem to upset her as well. She has lost a lot of weight. Her family is really worried.


If Amanda had been able to talk about what happened, perhaps the emotion and her bodily reaction would have dissipated, but she was too ashamed. So the emotional reaction established a memory loop, which could be activated by any association with that fateful meal.



For Amanda, fish had a special significance, but research has shown that most people are intolerant of a variety of different foods.  Some of these may carry a particular meaning.  Others excite the gut even in normal people –  hot spices, for example,  coffee and fats that stimulate a gastro-colonic reflex or beans, or some fruits and cereal fibre that are fermented to release gas in the colon.  People with sensitive guts should avoid or reduce the intake of such foods.      


It not always what we eat that upsets our guts but the way that we eat it.  The gut is designed to cope with three adequate meals a day; each takes about 4 hours to be digested before we feed hungry again.  Listen to your gut.  Don’t skip meals.  Only eat when you’re hungry and eat to fullness and no more.  Anxiety and greed can override satiety signals.   If you eat too much, then you will distend the stomach, overload the bowels and feel uncomfortable.  Too much fatty food will delay gastric emptying, induce nausea and cause cramping of the colon.  Alcohol is a gut irritant; indiscretion can upset the gut and other people. 


Take time to digest your food.  Eat slowly and in congenial company.  Never eat ‘on the hoof’.   Digestion is facilitated by the vagus nerve, which is active when we are relaxed.  If we don’t allow enough time for digestion, activity in the sympathetic nerves arrests digestion with pain, spasm and nausea.  Try to avoid difficult negotiations or arguments during mealtimes.    


As GK Chesterton  wrote;   


‘Our digestions ….. going sacredly and sensibly right, that is the foundation of all poetry …. 


We should all endeavour to lead poetic lives.   

This article was published in The Times yesterday.