Impact of a daily legume-based meal on dietary and nutritional intake in a group of omnivorous adults.

Adopting eco-friendly diets will demand the consumption of more plant-based protein food sources such as legumes. However, assessing the impact of such a dietary shift on the dietary and nutritional intake of traditionally omnivorous populations is needed. The objective of this study was to assess the impact of substituting a traditional omnivorous-based lunch for a vegetarian, legume-based meal on the daily dietary and nutritional intake in a group of omnivorous adults in the city of Porto, Portugal. Nineteen, non-vegetarian, healthy young adults consumed a vegetarian, legume-based meal from Monday to Friday, for 8 consecutive weeks. Socio-demographic data, health status, lifestyle-related information and anthropometric parameters were recorded. Three-day food records were used to collect food intake at baseline and week 8. European Food Safety Authority and World Health Organization reference values were used to assess nutritional inadequacies. Variables were described as medians (P₂₅ and P₇₅ ). Wilcoxon signed-rank and Mann-Whitney tests were used for statistical comparisons. A p-value of <0.05 was considered statistically significant. Participants consumed 38.0 (P₂₅  = 35.0; P₇₅  = 40.0) meals, resulting in an intake of 84.5 g (P₂₅  = 74.9; P₇₅  = 98.4) of cooked legumes per meal, meaning 11 subjects (57.9%) met the Portuguese guidelines for legume consumption (≥80 g/day of legumes). The current dietary intervention did not seem to aggravate the prevalence of nutritional inadequacies for the macro- and micronutrients tested, except for the case of vitamin B₁₂ (52.6% [95% CI: 28.9-75.6] vs. 78.9% [95% CI: 54.4-94.0]). This could be linked to the reduction of dietary sources of this vitamin which is an expected consequence of vegetarian meals. Dietary changes towards grain legume-based diets are desirable yet need to be carefully implemented to prevent exacerbating potential nutrient inadequacies, especially of vitamin B₁₂ .