Some people say they don鈥檛 feel good after eating gluten 鈥� but perhaps that鈥檚 because of its effects on mental health rather than on the gut.
Gluten is a protein in wheat that causes coeliac disease 鈥� a serious autoimmune condition 鈥� in about 1 per cent of people. A further 12 per cent of people say they experience bloating, cramps, tiredness, depression and other symptoms after they eat gluten-rich foods like bread and pasta.
But researchers can鈥檛 agree whether this 鈥渘on-coeliac gluten sensitivity鈥� is a real condition or not. Several studies have seemingly debunked it by showing that sufferers report the same gluten sensitivity symptoms even if they eat an inactive substance they think is gluten. Others have found that certain carbohydrates in wheat called fructans are probably more to blame for gut symptoms.
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However, even if gluten doesn鈥檛 cause gut troubles, it may trigger other non-digestive symptoms in some people, says Jessica Biesiekierski at La Trobe University in Australia.
Blinded challenges
Biesiekierski and her colleagues recently tested the effects of gluten on gastrointestinal and psychiatric symptoms in 14 people with self-reported gluten sensitivity. In one experiment, the participants were asked to eat a special form of yoghurt on separate days two weeks apart. On one of the days the yoghurt contained gluten, on the other day it was gluten-free.
In another experiment, volunteers were given two batches of muffins to eat a few weeks apart. Again, one batch contained gluten and one batch didn鈥檛. The gluten-containing and gluten-free formulations tasted the same and the participants didn鈥檛 know which ones they were eating each time.
The volunteers reported similar levels of bloating and cramps regardless of whether they ate the gluten-containing or gluten-free foods, reinforcing previous findings that gluten is not responsible for gut upsets in people without coeliac disease. The symptoms were probably caused by fear of eating gluten 鈥� a phenomenon known as the 鈥渘ocebo鈥� effect 鈥� says Biesiekierski.
But that wasn鈥檛 the only discovery. The participants reported feeling more tired after eating gluten-containing yoghurt and reported fewer positive emotions after consuming the gluten-containing muffins than after they ate the gluten-free foods. These effects were small, but they may explain why some people are convinced that they feel better after going gluten-free, says Biesiekierski, who聽presented the results at the聽 in Brisbane last week.
Feeling down
The findings replicate a previous study by Biesiekierski, which showed that gluten seemed to cause more symptoms of depression than an inactive substance in 22 people with gluten sensitivity. Similarly, a 2015 study led by Antonio Di Sabatino at the University of Pavia in Italy found that than an inactive substance in 59 gluten-sensitive individuals.
Michael Potter at the University of Newcastle in Australia says the evidence is becoming compelling. 鈥淭hese studies suggest there are definitely people who have reproducible mental health responses to gluten when they undergo blinded challenges,鈥� he says.
Biesiekierski is now trying to understand how these effects occur. Her team is looking for markers of stress and inflammation in blood, saliva and faecal samples collected from gluten-sensitive people after they eat gluten to see if they can uncover any clues.
An important thing to note is that even if gluten can directly impact mental health, it鈥檚 likely to occur in only a small number of sensitive people, says Biesiekierski. 鈥淲e鈥檙e certainly not saying that everyone will get depression after eating gluten,鈥� she says. Many people report improved mental health after going gluten-free, but for most, this is probably because they replace processed foods with fresh fruit and vegetables and adopt generally healthier lifestyles at the same time, she says.
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