For testing by sense of smell to work with any degree of certainty, there would have to be similar tests beyond self-reporting.
For testing by sense of smell to work with any degree of certainty, there would have to be similar tests beyond self-reporting.
I'm also skeptical of the idea that they make it harder for people with "real" intolerances - in the gluten example, there's been an explosion of GF foods, products, and menu signage ever since "gluten intolerance" became a familiar phrase.
Per celiac relatives, the gluten free "fad" has helped in the creation and availability of a lot more prepackaged foods in stores, but hurt in that a lot of restaurants don't take it fully seriously and do things in ways that result in cross-contamination, so there's more crap to wade through to find the truly safe gluten-free places at which to eat out.
Allaying Fears and Fallacies about Lactose Intolerance
https://www.sciencedirect.com/science/article/abs/pii/S00028...
Abstract
Public awareness and misunderstandings of lactose intolerance are at an all-time high. Many people erroneously believe they are lactose intolerant or develop gastrointestinal symptoms after intake of lactose. Consequently, lactose-containing foods such as milk and other dairy foods may be eliminated unnecessarily from the diet. Because these foods are a major source of calcium, low intake of them can compromise calcium nutriture. This, in turn, can increase the risk of major chronic diseases such as osteoporosis (porous bones) and hypertension. This review is intended to help dietetics professionals alleviate clients' fears about lactose intolerance and recommend dietary strategies to improve tolerance to lactose. Scientific findings indicate that the prevalence of lactose intolerance is grossly overestimated. Other physiologic and psychologic factors can contribute to gastrointestinal symptoms that mimic lactose intolerance. Scientific findings also indicate that people with laboratory-confirmed low levels of the enzyme lactase can consume 1 serving of milk with a meal or 2 servings of milk per day in divided doses at breakfast and dinner without experiencing symptoms. Several dietary strategies are available to help lactose maldigesters include milk and other dairy foods in their diet without experiencing symptoms.
The full study cites results from breath hydrogen tests to support its claim that "the prevalence of lactose intolerance is grossly overestimated" (as stated in the abstract, above). In particular:
A diagnose of lactose maldigestion [by an increase in breath hydrogen concentration of 20 ppm or more above the baseline value measured by a breath hydrogen test] does not predict the occurrence of symptoms of intolerance (12, 13, 15, 22, 28, 30). Nor can symptoms that follow lactose or milk intake be used to diagnose low lactase levels or lactose maldigestion (28). Intolerance symptoms after a lactose load have been demonstrated to occur in lactose maldigesters and lactose digesters (28).
Or, in other words (citing from the paper):
There is no clear correlation between lactose maldigestion, lactose intolerance, and milk intolerance. This may be explained by the subjectiveness of symptoms and the quantity of lactose or milk required to demonstrate symptoms. Strong beliefs may contribute to lactose intolerance; that is, persons who believe they are lactose intolerant may experience symptoms (12,30). Johnson et al (12) reported that when 45 lactase-deficient African-Americans were fed either a lactose-containing milk or lactose-hydrolyzed milk under boudle-blind conditions, on third of the subjects experienced some minor intolerance to both types of milk. The subjects' symptoms were not due to the lactose content of milk, but perhaps to social and cultural attitudes that influenced their ability to tolerate milk (12). In a more recent double-blind investigation, Vesa et al (3) found that one half of lactose maldigesters reported symptoms after consuming a lactose-free milk or a greater level of symptoms after intake of smaller rather than larger intakes of lactose. The symptomes were due, therefore, to factors other than lactose intake.
I note that this is one study and rather dated, but I just happened to stumble upon it while looking for something else. There may be newer studies in the literature that contradict this one's findings.
Edit: also, I used the term "gluten intolerance", not "coeliac disease". Please don't accuse me of being flippant about coeliac disease when I did no such thing.