People who claim themselves to be gluten sensitive or intolerant may not really have celiac disease. Instead, they may be experiencing a nocebo effect, which may be a cause for their gluten sensitivity perception. A recent study published in Nutrition in Clinical Practice examined who is more likely to diagnose themselves to have nonceliac gluten sensitivity (NCGS) even though they have no celiac disease. This population has gastrointestinal symptoms that improve after adopting a gluten-free diet. The results of the study show that among those who qualified in the study, those who self-diagnosed or were told to eat a gluten-free diet by an alternative health practitioner, general practitioner, or a dietitian are more likely to report to have NCGS.
The cause of NCGS remains somewhat of a mystery in current research. However, a small yet rigorous study that was published last year in Gastroenterology by Jessica Biesiekierski, Ph.D., and her colleagues showed that eight percent of the NCGS participants who ate any amount of gluten showed any significant gluten-specific effects. In the double-blind crossover study, 37 subjects with irritable bowel syndrome and self-diagnosed NCGS were randomly assigned to a two-week diet of FODMAPs, or reduced short-chained carbohydrates. Then they were put in a week-long low-gluten or high-gluten diet or a whey protein diet which served as a control group. At the end of the study, researchers found “no diet-specific changes” in the biomarkers in their blood serum or feces that indicate auto-immune activation, fatigue, or inflammation other than in the eight percent. Thus, Biesiekierski and her colleagues found no evidence that gluten-free diets have any “specific or dose-dependent effects” on those with NCGS with diets low in FODMAPs.
A recent review published in a Spanish-language journal Gastroenterlogía y Hepatología stated that patients with NCGS may have “overlooked minor CD [celiac disease] and diarrhea-predominant irritable bowel syndrome” based on recent studies. Researchers postulated that the real culprit behind NCGS may be from FODMAPs from wheat rather than gluten itself. Since there is no current evidence that eating gluten causes gluten sensitivity, the nocebo effect may be the best hypothesis to explain this phenomenon.
Although the nocebo effect is lesser known than its positive counterpart, the placebo effect, the former has been known to cause illness and other manners of pain and discomfort due to negative suggestions and expectations. For example, physicians and nurses could sometimes unintentionally give negative outcomes and suggestions about a patient’s condition and treatment, which can cause a patient’s health to spiral even further down. According to a German-language review in Deutsches Aerzteblatt International, the nocebo effect is learned by “Pavlovian conditioning and reaction to induced expectations.” Therefore, the words that clinicians use can negatively (or positively) affect patients’ outcome.
By Nick Ng