Of all the foods that are claimed to be responsible for bloating and other symptoms of IBS, bread would appear to be the most common. No fewer that 50% of women and a substantial proportion of men suspect that bread may be causing bloating. So how is it that a food that has been the very staff of life for millennia could be making so many of us ill?
Coeliac Disease and Non Coeliac Gluten Sensitivity.
We know that 1 in 100 of the population will have Coeliac Disease and will need to go on a gluten free diet. Half of that number may also be specifically sensitive to wheat and be diagnosed with non-coeliac gluten sensitivity (NCGS) but this is only a tiny fraction compared with the number of people who are upset by eating bread.
Most of the wheat consumed in the UK comes from Canada and contains over 1% of indigestible fructans and galactans. These are complex sugars and components of FODMAPs that escape absorption in the small intestine and travel through to the colon, where they are fermented, releasing gas. That’s not a high percentage compared with onions or pulses, but in people who eat a lot of bread, it may be enough to cause symptoms. However, no study has specifically implicated wheat by rechallenging people on FODMAP exclusion diets with bread.
Bread consumption has dropped by about 50% in the last 50 years and yet wheat intolerance has increased and the commonest symptom is bloating. Since the 1960s, most bread purchased in the UK has been made by the Chorleywood method, a faster process with minimal fermentation that results in loaves that are softer, last longer and toast better. Chorleywood adds extra yeast and enzymes to the dough, but while these might be implicated in bloating, they are destroyed by the baking process. It also adds preservatives, calcium and other nutrients, notably vitamins . But perhaps the ultrashort fermentation and the soft, pappy texture creates bread with more fructo-oligosaccharides. A recent study showed that faeces from IBS patients cultured with Chorleywood bread or commercially available low yeast fermented bread, had lower concentrations of bifidobacteria and generated more gas than when cultured with traditional long fermentation sour doughs.
Many people eat substantial amounts of bread as toast. When bread is toasted, the starch is twisted and retrograded so that less can be digested and more fermented.
Giving a loaf a bad name
There has been so much bad press about bread and bloating over the last few years that many people with a sensitive gut may seize on wheat as the source of their problems. But it may not always be the biological effect of wheat on the gut, but rather the anxiety over the possible effect of wheat.
Bloating is defined as a sensation of abdominal pressure. Nevertheless, it is only associated with increased gas content or production in about 50% of patients, even though the abdomen may appear distended towards the end of the day. Physiological studies have shown that the protrusion of the abdomen may be due to the combined effect of relaxation of the abdominal wall and contraction of the diaphragm. These muscular changes may be reflex adaptations to the sensation of abdominal pressure; the descent of the diaphragm enables more air to be taken in while abdominal relaxation relieves the pressure. Other experiments have demonstrated an increase in visceral sensitivity, which is often increased by stress. This might explain the observation that the bloated abdomen can inflate when patients put their hands in ice cold water and deflate when they go to sleep or are anaesthetised or hypnotised.
So while bloating can be the abdominal response to increased abdominal content (gas, fluid, fat, faeces or a foetus), creating more space to breathe, it may also be the response to a heightened sensation of abdominal pressure, brought on by stress or fear.
So might the apprehension of a distended abdomen in fashion conscious modern young women bring on the symptom they most fear? Might bloating be a life style illness? In a study reported in a recent symposium on Bread and Bloating that I attended, bread produced less abdominal distension but higher rates of reported bloating. As always, our experience is often conditioned by our beliefs.