“GIVE us this day our daily bread.” Wheat was one of the first crops to be domesticated and for thousands of years it has been a staple food for a large swathe of the world. It is deeply engrained in our culture and consciousness. What could be more evocative of healthy goodness than the delicious smell of a home-baked loaf? So it comes as a shock to many to learn that wheat is now under attack.
Wheat is toxic, addictive and makes you want to eat more junk foods, claim some. They say it causes food allergies, bloating and makes you fat. Others even blame it for various mental disorders. And many people seem to believe these ideas, often much to the annoyance of friends and family who have to cater for them. Demand for gluten-free food is rising rapidly, to the extent that many restaurants now promote gluten-free dishes on their menus. Eating gluten is frowned on in some quarters. “Here in LA, it’s comparable to Satanism,” .
Yet as Kimmel noted, most people can’t even say what gluten is. So what are the facts about gluten and wheat in general? Is it really the seed of all evil, or is this all much ado about nothing? The answer is complex. There is no doubt that some people – but only a tiny minority – must avoid gluten. For others who blame gluten for their gut-related woes, however, the problem may not be gluten but components of wheat also found in many other foods. And for healthy individuals, the benefits – or otherwise – of going wheat-free may depend partly on your genes and partly on what you eat instead. Wheat is not a squeaky-clean superhero, but neither is it the supervillain some claim.
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Of all the constituents of wheat, gluten has been singled out by some as public-health enemy number one. Gluten is a composite of two proteins, glutenin and gliadin, and it forms a network of fine stretchy strands when wet. This is what gives dough its elasticity and makes it so versatile, allowing it to be turned into everything from bread to cakes to pasta.
Gluten is found in other grains besides wheat, including barley and rye. Going truly gluten-free means excluding the vast number of foods containing these grains, and often things like oats, which are processed with the same machinery as wheat.
All this is entirely necessary if you have a serious condition called coeliac disease. It is caused by the immune system mistakenly producing antibodies against gluten that damage the hair-like villi that line the gut, leading to malnutrition. Blood tests for the antibodies suggest that it affects as many as one person in 100, although many people have only mild symptoms and so are often unaware of their condition.
Far rarer are wheat allergies, which can involve one or more of a number of proteins. Symptoms appear rapidly if wheat is eaten or flour dust breathed in, or sometimes if people exercise soon after eating wheat.
What about those who don’t have coeliac disease or allergies to wheat proteins? Gluten is now being blamed for causing bloating, gut pain, headaches and lethargy in many people in whom there is no immune reaction. The syndrome has been dubbed , and there have been claims that up to a fifth of people have it.
But does NCGS really exist? Several small studies have found that some individuals do have gut-related symptoms when they eat wheat that often clear up if they change their diet. Peter Gibson of The Alfred Hospital and Monash University in Melbourne, Australia, was first to test the effects of gluten in a randomised, placebo-controlled trial – the gold standard for medical research. He recruited 34 non-coeliacs with gut symptoms that largely disappeared when they went gluten-free. He kept them on a gluten-free baseline diet, and also gave them bread and muffins that – unbeknown to the participants – either did or didn’t contain gluten. Those who ate the gluten-containing muffins .
This small study helped convince many doctors that NCGS was a genuine condition, but Gibson himself was not satisfied. “There’s no doubt that wheat is a major cause of bloating and abdominal problems,” he says. “The trouble is that wheat has more than just gluten in it.”
He wondered if the problem might instead be caused by members of a set of sugars that his group has dubbed FODMAPs (fermentable oligosaccharides, disaccharides, monosaccharides and polyols). So Gibson did another study with 37 recruits with suspected NCGS. This time, however, they were put on a diet that was both gluten-free and low in FODMAPs. Then some had high or low amounts of gluten, or a milk-protein control, added to their diets. There was no difference between the three groups’ response, , suggesting gluten is not in fact the root cause of their problems.
In other words, people who think they are gluten-sensitive might instead be reacting to the FODMAPs found in wheat. are poorly absorbed in the small intestine and so instead tend to be eaten by bacteria living further down the digestive tract, producing an abundance of gas. They also attract water, leading to bloating, flatulence, loose stools and worse in people with sensitive bowels.
“Some people who think they are gluten sensitive may instead be reacting to certain sugars”
Crucially, the various kinds of FODMAPs aren’t just found in wheat, but in lots of foods including many fruits, vegetables and dairy products, so no one is suggesting remaining on a low-FODMAP diet permanently (see “Thinking of going gluten-free?”). People who suffer when they eat lots of certain FODMAPs should be able to tolerate small amounts, because this is not an immune disorder like coeliac disease or wheat allergies. Many simply avoid cooking with onions, Gibson says, which are very high in fructans, a group of FODMAPs also found in wheat.
The small size of the studies done so far, though, means the science is far from settled. There may be a subset of people who don’t have coeliac disease but who do get gut problems when they eat gluten, through an as-yet-undefined mechanism.
But of course, people with gut problems are far from the only ones going gluten-free. About a third of the US population say they would like to cut down or eliminate gluten from their diets, if is to be believed. Some see it as a way of shedding a few pounds. Others just think eliminating wheat from their diet is the healthiest option.
Where did this idea come from? Two bestsellers probably have something to do with it. In Wheat Belly, published in 2011, William Davis argues that the overenthusiastic consumption of wheat is the main cause of the obesity and diabetes crisis in the US. Meanwhile, in Grain Brain, published last year, David Perlmutter suggests that carbohydrates, including those in whole grains like wheat, are a leading cause of conditions including dementia, ADHD, anxiety and depression.
However, the evidence for many of the claims in the books, or their interpretation of it, is questionable. Take the claim that the spike in blood sugar caused by eating wheat and other grains triggers inflammation in the brain and thus Alzheimer’s disease. One piece of evidence cited by Perlmutter is reporting that even mild elevations in blood glucose in healthy individuals put them at risk of developing dementia.
Yet of the University of Washington in Seattle, who led that research, disagrees with Perlmutter’s interpretation. “Our study says nothing about dietary sugar, dietary carbohydrates or dietary anything,” Crane says. “What we studied was a five-year average of people’s blood sugar levels. This is not at all the same as how much your blood sugar goes up or down after a single meal.”
This is not to say that the glycaemic index (GI) of food – how quickly it releases sugar – does not matter. People who eat food with a low GI, which release sugars slowly, . And some researchers now regard Alzheimer’s as a form of diabetes.
But there is no reason to single out wheat, or other grains, on this basis. The and is typically lower than that of, say, cooked potatoes. What’s more, your risk of getting disorders such as diabetes and Alzheimer’s is likely to depend on a complex interplay between your genes, the number and form of calories you consume and how much exercise you do, not solely on whether you eat wheat.
Fattening and addictive?
But wheat is addictive, cry its critics. For example, Davis claims that wheat proteins break into fragments that act on opioid receptors in the brain, making us want more. “That’s an extraordinary statement,” says Gibson. These opioid-like peptides do exist, but whether they affect the brain in any way is unclear. And even if they do, proteins from milk, rice, meat and spinach all produce similar fragments, so again there is no reason to single out wheat.
What about the claim that wheat is particularly fattening? “Wheat is no more fattening than any other carbohydrate,” says Gary Frost, who studies nutrition and dietetics at Imperial College London. “I think the reason wheat has got a bad press is just that it’s a very commonly consumed cereal, so it’s hardly surprising that if you start to miss it from your diet then you start to lose weight.” Cutting out wheat, after all, means cutting out many high-calorie foods such as cakes and biscuits.
But swapping cakes and biscuits for fruits and vegetables is one thing. Swapping wholewheat bread for processed, gluten-free substitutes is quite another. A team in Spain and found that, in general, they contained more fat and less fibre than those of people who do eat gluten.
That is bad because not only does eating a high-fibre diet curb your appetite, it also reduces your chances of developing several cancers. And wheat, particularly wholegrain wheat, is a major source of fibre.
So eating gluten-free foods is not necessarily less fattening, nor even healthier in general. “People tend to think they are more nutritious, but in general they are low in fibre, higher in glycaemic response and more costly,” says Julie Jones at St Catherine University in St Paul, Minnesota.
For many people, though, the issue is not how wheat stacks up against alternative foods. Instead, they have been convinced by the claim that humans did not evolve to eat a lot of carbohydrates. But this is a dubious argument for several reasons. Just because our ancestors ate lots of meat doesn’t necessarily make it good for us. In any case, it is not at all clear that all our ancestors did eat lots of meat. Some , just as the hunter-gatherer Hadza people in Tanzania do today.
“It’s hard to avoid eating wheat, but a healthy diet doesn’t need to include it”
What’s more, it may be that , just as the ability to digest milk as an adult – lactose tolerance – evolved independently in several parts of the world after the domestication of cattle. Earlier this year, Mario Falchi at Imperial College London and his colleagues discovered that people with fewer copies of a gene called AMY1 are more likely to be obese than those with lots of copies.
This gene produces an enzyme found in saliva called amylase, which breaks down starch. Falchi thinks it might influence us in subtle ways, such as preparing the body for what we are eating. A found that when people with many copies of AMY1 consumed a starchy drink, their blood sugar levels showed less of a spike than when people with fewer copies drank the same. That suggests people with many copies are less likely to develop disorders like diabetes even if they eat lots of high GI carbohydrates. This is speculation, though, and in any case there’s no simple test you can take to find out if you have lots of copies of AMY1 or very few.
For some, though, avoiding wheat is not just about physical health. Gibson was struck by the fact that many of his patients chose to remain on a gluten-free diet even after he showed that their symptoms were not caused by gluten. “Most of them said they just felt better,” says Gibson. It sounds like a classic example of the placebo response, but they might just be on to something.
When Gibson did another small double-blind, placebo-controlled trial in 24 people with irritable bowel syndrome, those given gluten – unbeknown to them – scored more highly on a questionnaire assessing levels of depression, .
As ever, the results of such a small study have to be treated with caution. But then again, even if this and the many other claims about the evils of wheat don’t stand up, there is no need to eat the stuff. It is hard to avoid eating wheat, but a healthy diet doesn’t have to include it. So if it makes you feel happy, lose the loaf.
Leader: “Time for a grain of truth about wheat and gluten”
Thinking of going gluten-free?
If you have health problems that you suspect are linked to wheat, don’t just go gluten-free. “You need to get tested to exclude the possibility of coeliac disease,” says Gerd Bouma, a gastroenterologist at VU University Medical Center in Amsterdam, the Netherlands. The first step is to test for blood antibodies to gluten, and this will not work if you haven’t been eating gluten.
If you have abdominal problems such as bloating, and coeliac disease has been ruled out, the cause of your symptoms might not be gluten but one or more poorly absorbed sugars known collectively as FODMAPs (see main story). Wheat happens to be high in certain FODMAPs but so is a frighteningly long list of other foods and drinks, including onions, asparagus, peppers, apples, dried fruits, peas, honey, milk, ice cream, many sweeteners and beer. The good news is that you don’t need to cut them all out forever – instead the idea is to cut them out for a few weeks and gradually reintroduce foods to see which kinds of FODMAPs disagree with you.
“You learn which foods affect you and can adjust your diet accordingly,” says Peter Gibson of The Alfred Hospital and Monash University in Melbourne, Australia. It’s recommended that you get your doctor to refer you to a dietician if you want to try a low FODMAP diet but booklets and are available too.
If you are perfectly healthy but want to go gluten-free because you believe it will make you even healthier, just watch what you eat instead. Many off-the-shelf gluten-free alternatives are higher in salt and fat, for instance. They can also be bad for your bank balance.
This article appeared in print under the headline “The blame grain”
