Diagnosis of lactose intolerance and the “nocebo” effect: The role of negative expectations

Symptoms occurring after consuming milk among children, youth and students with hypolactasia

“…Similar observations have been presented by other researchers [12,13,14]. Survey shows that people commonly combined the ingestion of lactose with intestinal ailments, including mainly the occurrence of abdominal pain, even in the absence of evident hypolactosis data (negative HBT test) [15,16,17,18,19]. Symptoms often regarded as NL are secondary to motor disorders of the gastrointestinal tract [15,20,21,22,23,24].…”

The effect of gluten on intestinal fermentation, gastric and gallbladder emptying in healthy volunteers

“…In addition, it was shown that in HV a gluten-containing meal increased intestinal fermentation in comparison with a gluten-free meal [30]. It should be noted that these results were collected in accordance with unblinded protocols: both placebo and nocebo effects [31,32] have been unequivocally shown in functional gastrointestinal patients [33,34], with symptoms overlapping with those of NCGS.…”

Placebo effects and their determinants in gastrointestinal disorders

“…150 In a study of >300 patients with a negative hydrogen breath test following lactose challenge, nearly 10% reported abdominal symptoms during the test, and when they were deceptively given glucose before another breath test, half of them reproduced their symptoms, as did 25% of those with lactose malabsorption. 151 Similarly, among patients with claimed hypersensitivity towards milk products, one-third had a negative hydrogen breath test after lactose challenge, 152,153 and most tolerated moderate amounts of milk (that is, 250 ml daily) with minor symptoms. Symptoms are usually higher in the home environment than in the laboratory setting, 154 and symptoms reports were associated with increased somatization scores and other psychopathological characteristics, 155 indicating that the reported symptoms of lactose intolerance in many patients might constitute nocebo responses to reports in public media, patient communication and other sources of information.…”