Between 1 and 2 per cent of the population is gluten or wheat intolerant. They get stomach pains, constipation and diarrhoea, most often because they have coeliac disease, a genetic disorder of the small intestine where the immune system gets it wrong and thinks that the gluten is attacking it, causing inflammation. Rather more people claim gluten intolerance than actually have it – for the rest it is a ‘nocebo’, the negative equivalent of a placebo effect, where believing something is bad for you causes pains with no physical cause.
There are simple tests that your GP can perform to check if you do have a genuine gluten intolerance. If this proves to be the case, then it’s a matter of ensuring that the diet is gluten-free, something that is increasingly easy with a wide range of gluten-free products available in the supermarket. In general, food should be fine as long as you avoid wheat, barley and rye. (Oats, while not a problem in themselves, are probably best avoided also as they are often contaminated with gluten from other grains.) Other cereals like maize and rice are fine.
There has been something of a fad diet of avoiding gluten – the kind of diet often endorsed by celebrities rather than experts – in those who don’t have a gluten intolerance, probably on the assumption that people must be intolerant because there is something toxic in the gluten and that avoiding gluten must be ‘good for digestive health’. In fact, it’s the reverse – people who are gluten intolerant have a mutation that makes them react badly to a harmless substance that is a normal part of our diet.
The general argument for a gluten-free diet if gluten doesn’t cause you problems is open to interpretation. Here’s nutritional therapist Deborah Thackery, quoted in the Morrison’s supermar- ket magazine:
Gluten doesn’t need to be in sausages or many other foods in which it is often present. There is growing evidence that gluten is difficult to digest and while we need protein, the right sort of fats and plenty of vitamins and minerals, we don’t need gluten. All of these nutrients can be found in other, non-gluten-containing foods.This doesn’t make a lot of sense as dietary advice – after all, fibre is hard to digest, but it’s still good for you (see Fibre). All the evidence is that supermarkets are using ‘gluten-free’ rather as they do the ‘organic’ label: as a way to put a considerable mark-up on a product that doesn’t cost them much more to produce. Gluten-free products can be a rip-off. Trials have failed to demonstrate any health benefit to a gluten-free diet for those who aren’t intolerant, and it makes it significantly harder to get the fibre (and some vitamins) we all need. What’s more, many gluten-free products are higher in fat than their normal equivalents, as something has to be used as a substitute to give the textural contribution of gluten. So, a gluten-free diet is best avoided if you don’t have a medical reason to be on one.
A review published in November 2014 highlighted that those who aren't intolerant shouldn't avoid gluten, but should go for products made from whole grain cereals. The report concluded:
There is overwhelming evidence of clear health benefits of a whole grain based diets featuring store cupboard staples such as bread and cereal made from lightly processed wheat. The benefits are increased where whole grains have undergone relatively little processing... the scientific evidence behind many of the most popular wheat and carbohydrate free diets turns out to be surprisingly thin and selectively used... Whole grain products are undoubtedly good for health and given their multiple beneficial aspects could easily be described as a super food. It might be possible to argue that they are superior to many other fruit and vegetable super foods since they have multiple modes of action and provide both short- and long-term health benefits.The review was funded by the company that makes Weetabix, however it was undertaken by the University of Warwick, which points out that the 'company had no input into the conclusions of the research'. While clearly such research is beneficial to the manufacturer, there is no reason to suppose that the funding would bias the outcome.
• Placebo effect