Gluten free – The magic diet bullet? Some food for thought…
by guest blog author Rebecca Haskoll
Not so long ago, ‘gluten’ was a word reserved for science books, bakers and those with coeliac disease (CD). CD is an autoimmune reaction to gliadins (the soluble fraction of gluten), which results in damage to the small intestine causing nutrient malabsorption. Symptoms of CD include diarrhoea, anaemia, fatigue and sometimes an intensely itchy rash called dermatitis herpetiformis. There is no drug treatment or cure for CD, just adoption of a gluten free diet (GFD) for life.
Gluten is in a LOT of foods – not just the obvious ones such as bread and pasta, but also in flavourings, soups, sauces, beer and even chocolate bars – so coeliacs must find GF substitutes.
Five years ago, most of those substitutes were only available on prescription. Then came the ‘Free From revolution’. Genius was the first company to commercialise GF bread. Supermarkets began to market their own ‘Free From’ ranges. Suddenly whole aisles were dedicated to living GF. Recent research indicates that 16.5% of the UK population now regularly buys GF products.
But how did this happen? After all, the prevalence of CD in the UK is estimated only to be 0.8-1.9%. Although NICE suggests that as many as 1 in 100 people may have CD, many will remain asymptomatic and presumably won’t adopt a GFD. Non-coeliac gluten sensitivity (NCGS) has an estimated prevalence of 6-10%. NCGS seems to overlap with irritable bowel syndrome and there is a question over whether symptoms are caused by gluten proteins or byfermentable carbohydrates. Nevertheless, this population is likely to choose GF foods.
The only other proven reason for someone to adopt a GFD is wheat allergy. So what else could account for the rise in ‘gluten free living’?
Celebrities seem to love a GFD. Everything from Miley Cyrus’s tweets to Gwyneth Paltrow’s cookbooks and tennis supremo Novak Djokovic’s diet plans have exclaimed that going GF has positive health effects. Gwyneth’s mental clarity improved. Miley lost weight. Novak won Grand Slams. What have the rest of us got to lose? More on that later…
Bestselling diet books such as Grain Brain by American neurologist Dr David Perlmutter have received extensive coverage in the popular press. Dr Perlmutter believes the consumption of carbohydrates and gluten causes neurological manifestations (everything from headaches to Alzheimer’s) probably in ALL humans.
In a recent interview, Dr Perlmutter cites several papers. On further reading, their authors are not quite as adamant about the ‘all humans’ part of his theory: Hadjivassiliou et al. (also here) hypothesise that patients with CD-like blood-test results who continue to consume gluten may develop neurological dysfunction. Fasano discusses the possibility that gluten-induced protein expression implicated in ‘leaky guts’ may also cause blood-brain-barrier permeability (it is not conclusive that this protein causes a critical level of gut permeability in non-coeliacs). Both authors acknowledge that large cohort studies are needed.
So you don’t have CD but decide a GFD is for you… The everyday realities are that avoiding gluten is really quite difficult and GF foods are expensive. But are there potentially more serious consequences to going GF than just being out of pocket? Coeliacs on strict GFDs have been shown to have lower intakes of some micronutrients and lower fibre intakes than the general population. This may be because GF staples such as breads are less likely to be fortified than their wheat-based counterparts or because many GF foods – particularly baked goods – do not have the best texture, so are abandoned in favour of other foods that may lack the nutrients found in glutinous grains. If you don’t need it, is it worth the sacrifices?
Gluten free the magic diet bullet? I’m not so sure…
Becky is a student dietitian at King’s College London, interested in role of nutritional factors in managing chronic illness.