Many people report bloating and other health issues after eating bread, pasta and other gluten-containing foods.
For decades, gluten, a naturally occurring protein in wheat, rye and barley, has been blamed as the culprit, spawning a billion dollar industry in gluten-free products.
One in 10 (about 1.8 million Australian adults) avoid or limit wheat-based products to minimise the risk of gastrointestinal symptoms and fatigue they attribute to the foods, according to CSIRO data.
About one to two per cent of the Australian population have coeliac disease, an immune reaction to gluten which causes small bowel damage.
However, for those with non-coeliac gluten sensitivity, mounting research suggests that fructan, a carbohydrate in wheat and other foods, is more likely the true cause.
Building on his own past research, Peter Gibson, a professor of gastroenterology at Melbourne’s Monash University, and his colleagues, tested 59 people with non-coeliac gluten sensitivity for their reaction to gluten, fructan and a placebo (hidden in muesli bars).
While both gluten and placebo produced symptoms, fructan induced symptoms the most.
The study, published in Gastroenterology in February, “gave evidence that gluten is not a cause in the vast majority of self-reported non-coeliac gluten intolerance”, Professor Gibson says.
“The fructans in the wheat are.”
His findings possibly explain why many sufferers get only partial improvement of symptoms after removing gluten.
Fructan, a naturally occurring carbohydrate found in wheat, rye, onions, garlic and other foods, is one of a group of short-chain carbohydrates collectively known as FODMAPs that may cause a sensation of bloating and other gastrointestinal symptoms in sensitive individuals.
FODMAPs (which stands for fermentable oligosaccharides, disaccharides, monosaccharides and polyols) are found in specific fruit, veg, cereals and milk.
For a list of FODMAP foods visit the Monash site
As well as fructans, they include galacto-oligosaccharides or GOS (high in legumes), lactose (in milk and dairy products), fructose (rich in honey, corn syrup and certain fruits) and polyols such as mannitol and sorbitol (found in some fruit and veg and used as an artificial sweetener).
Like many carbohydrates, FODMAPs are poorly absorbed and digested by the body, Professor Gibson, explains.
“They either get very slowly absorbed from the gut or they don’t get digested and go all the way down, through into the large bowel.
“Because they’re small molecules, they have this osmotic drag and they bring water into the bowel and are also very fermentable by bacteria.”
This rapid fermentation produces gas that stretches our bowel, creating the bloating sensation many of us are familiar with after consuming an Indian meal of high FODMAP lentils, naan bread and onions.
Fortunately, apart from symptoms, consuming FODMAPs won’t cause damage to your body, Professor Gibson says.
“It won’t impair your longevity, or cause inflammation or ulceration or anything.”
In fact, the idea isn’t to avoid them, but to limit those that cause unpleasant symptoms.
“We need some of them,” he says.
“They’re normal and they’re good for you. Most things in the diet have got a double-edged sword – a small amount is good and a large amount is not so good.”
And, as some FODMAPs, such as GOS, have prebiotic qualities that encourage good bacteria, in fact, they’re essential to our health.
Our bodies response to the indigestible components of FODMAPs is normal.
“We all handle them [FODMAPs] the same way,” Professor Gibson says.
What differs is our bowel’s response to distension. “If you’ve got a very sensitive bowel, it’s not so good having lots of them,” he says.
And, they affect each of us differently. “For some people fructose is not a problem. For some it’s a major thing,” he says.
The microbiota in your gut can affect your sensitivity to different FODMAPs. For instance, “some people have a spectrum of bacteria that loves galacto-oligosaccharides,” Professor Gibson says.
Going on a low FODMAP diet, and slowly reintroducing foods, can help people weed out those that might be causing problems.
“A low FODMAP diet is quite restrictive,” he adds.
“It’s not meant to be the long-term diet. What you end up with is a personalised diet where you know what you can tolerate.”
He emphasises that bloating is extremely common across many conditions. In most cases it’s a normal physiological reaction to the distension of the gut that occurs when we eat food.
“It’s when it’s ongoing, every day, or several times a week – that’s when we think bloating is not a good thing.”
Other things that can cause the sensation of bloating include functional gastrointestinal disorders, and in females, endometriosis, and more rarely, ovarian cancer, which presents lower down in the abdomen, he says.
While it might be FODMAPs causing your bloating, it’s important to rule out other possibilities.