Energy intake misreporting among omnivores, vegetarians and vegans: A multi-cohort analysis

Misreporting of energy intake in community-dwelling adults is a frequent problem in nutrition studies with large implications. Vegans and vegetarians have been characterized as particularly health-minded, and the concept of dietary identity is central to many individuals following these diets, suggesting a stricter and more consequent eating behavior. We thus investigated whether vegans and vegetarians are less likely than omnivores to misreport energy intake due to diet-associated lifestyle behaviors and personality traits.

We pooled two German cross-sectional studies (the LAKE study and the Freiburg-METABO study) which included extensive weighed food diary records. Moreover, we analyzed US-based National Health and Nutrition Examination Surveys (NHANES) data. Multivariate logistic regression models were used to investigate potential associations between diet type and energy underreporting. A validated predictive equation based on doubly labelled water measurements was used to determine under-reporter status.

No association between vegetarian status and underreporting was found in both German studies (n = 206 participants). Underreporting frequency was below 10% in all diet groups; the lowest frequency was found in vegans. NHANES data (n = 8445 participants) suggested an association between vegetarian status and underreporting only after adjusting for BMI - a potential mediator in this context. In this case, lacto-ovo-vegetarianism was associated with significantly higher odds for underreporting (odds ratio: 1.79 (1.05-3.07) with a p-value of 0.034).

The results indicate that vegetarian status is not associated with energy intake misreporting contributing important evidence to the ongoing debate on dietary intake, energy density and nutrient adequacy in plant-based diets.