We have read with interest the article, “Dietary characteristics of Mexican patients with irritable bowel syndrome: Is there a distinction from the general population?” by Amieva-Balmori et al.,1 which addresses a relevant theme, but we consider it pertinent to make some observations to enrich the methodological and conceptual discussion of the study.

The analysis does not specify the clinical moment at which the patients were evaluated nor under which criteria the health status of the controls was confirmed. For the controls, it is necessary to demonstrate that the absence of disease is not synonymous with health (being healthy). The authors should have clarified how they ensured that the controls did not present with other diseases. For the patients, it would have been ideal to describe the “serious diseases that could affect nutrient intake”. We also believe it is important to emphasize that “dietary characteristics” is an incorrect designation used by the authors regarding their nutrient analysis. Dietary characteristics are those that indicate what and how we eat, and in that sense, the authors fail to describe the intake of specific ingredients, dietary patterns, diet quality, types of sugars, and trigger foods. Only evaluating the nutrient profile limits the possibilities of identifying the dietary factors that trigger symptoms in irritable bowel syndrome (IBS).

We also wish to comment on other methodological questions. The first is the description of the selection process of patients as “voluntary participants” (the literal translation of the Spanish text referred to here would be “voluntary invitation”), which is not clear and could lead to doubts as to the randomness of the sample and even be misinterpreted as recruitment coercion. Second, the authors carried out a FODMAP analysis limited to a qualitative categorization, restricting the capacity to infer relative differences between groups that would be a greater contribution and benefit to the readers.2 Third, certain aspects that authors of articles on nutritional epidemiology should consider are clinical differences between groups that should be controlled in the study design, because disparities in age and body mass index (BMI) can be important biases. Likewise, reporting data utilizing the term “vegetables” as separate from fruits, cereals, and legumes needs to be clarified, given that taxonomically, they all belong to the vegetable kingdom. It would have been relevant to discuss the possible role of eating disorders in the population studied, as has been done previously.3 And last, the lack of an adequate sample size limits the inferences that could be made.

In conclusion, even though the theme is a pertinent one, the methodological deficiencies of the article weaken the conclusions the authors arrived at. Future studies whose aim is to report dietary characteristics should consider these relevant aspects.