Search

Research has shown that vegetarian diets have a low environmental impact, but few studies have examined the environmental impacts and nutritional adequacy of these diets together, even though vegetarian diets can lead to nutritional issues.Our objective was to optimize and compare 6 types of diets with varying degrees of plant foods (lacto-, ovolacto-, and pescovegetarian diets and diets with low, medium, and high meat content) under nutritional constraints.Consumption data in 30,000 participants were derived from the French NutriNet-Santé cohort using an FFQ. Diets were optimized by a nonlinear algorithm minimizing the diet deviation while meeting multiple constraints at both the individual and population levels: nonincrease of the cost and environmental impacts (as partial ReCiPe accounting for greenhouse gas emissions, cumulative energy demand, and land occupation, distinguishing production methods: organic and conventional), under epidemiologic, nutritional (based on nutrient reference values), and acceptability (according to the diet type) constraints.Optimized diets were successfully identified for each diet type, except that it was impossible to meet the EPA (20:5n-3) + DHA (22:6n-3) requirements in lacto- and ovolactovegetarians. In all cases, meat consumption was redistributed or reduced and the consumption of legumes (including soy-based products), whole grains, and vegetables were increased, whereas some food groups, such as potatoes, fruit juices, and alcoholic beverages, were entirely removed from the diets. The lower environmental impacts (as well as individual indicators) observed for vegetarians could be attained even when nutritional references were reached except for long-chain n-3 (omega-3) fatty acids.A low-meat diet could be considered as a target for the general population in the context of sustainable transitions, although all diets tested can be overall nutritionally adequate (except for n-3 fatty acids) when planned appropriately.This trial was registered at clinicaltrials.gov as NCT03335644.

International audience; Background: The postprandial retention of dietary protein decreases when the prevailing protein intake increases. Objective: We investigated the influence of the prevailing protein intake on the regional utilization and anabolic use of wheat protein during the postprandial non-steady state in humans. Design: Healthy adults (n = 8) were adapted for 7 d, first to a normal-protein diet (NP: 1 g .kg -1 .d-1) and then to a high-protein diet (HP: 2 g .kg-1 .d-1). After each adaptation period, the subjects received the same single, solid mixed meal containing (15N)-labeled wheat protein. The postprandial kinetics of dietary nitrogen were then measured for 8 h in blood and urine. These data were further analyzed by using a multicompartmental model to predict the postprandial kinetics of dietary nitrogen in unsampled pools. Results: The postprandial whole-body retention of wheat protein nitrogen, measured 8 h after meal ingestion, decreased by 10% when the subjects switched from the NP diet to the HP diet. According to modeling results, this resulted from an increased splanchnic utilization of dietary nitrogen for urea production, whereas its incorporation into splanchnic proteins was unchanged, leading to a 20-30% decrease in peripheral availability and anabolic use in HP- adapted compared with NP-adapted subjects having ingested the same protein load. Conclusions: By combining clinical experimentation with compartmental modeling, we provide a global overview of postprandial dietary protein metabolism. Increasing prior protein intake was shown to reduce the postprandial retention of wheat protein nitrogen, mainly by diminishing the efficiency of its peripheral availability and anabolic use

absent

Background: The systemic availability of oral/dietary arginine and its utilization for nitric oxide (NO) synthesis remains unknown and may be related to a competitive hydrolysis of arginine into urea in the splanchnic area and systemic circulation. Objectives: We investigated the kinetics and dose-dependency of dietary arginine utilization for NO compared with urea synthesis and studied the characteristics of the arginine-NO metabolic system in healthy humans. Design: We traced the metabolic fate and analyzed the utilization dynamics of dietary arginine after its ingestion at 2 nutritional amounts in healthy humans (n = 9) in a crossover design by using [N-15-N-15-(guanido)]-arginine, isotope ratio mass spectrometry techniques, and data analysis with a compartmental modeling approach. Results: Whatever the amount of dietary arginine, 60 +/- 3% (+/-SEM) was converted to urea, with kinetics indicative of a firstpass splanchnic phenomenon. Despite this dramatic extraction, intact dietary arginine made a major contribution to the postprandial increase in plasma arginine. However, the model identified that the plasma compartment was a very minor (similar to 2%) precursor for the conversion of dietary arginine into NO, which, in any case, was small (

Background Compared with slow proteins, fast proteins are more completely extracted in the splanchnic bed but contribute less to peripheral protein accretion; however, the independent influence of absorption kinetics and the amino acid (AA) pattern of dietary protein on AA anabolism in individual tissues remains unknown. Objective We aimed to compare the postprandial regional utilization of proteins with similar AA profiles but different absorption kinetics by coupling clinical experiments with compartmental modeling. Design Experimental data pertaining to the intestine, blood, and urine for dietary nitrogen kinetics after a 15N-labeled intact (IC) or hydrolyzed (HC) casein meal were obtained in parallel groups of healthy adults (n = 21) and were analyzed by using a 13-compartment model to predict the cascade of dietary nitrogen absorption and regional metabolism. Results IC and HC elicited a similar whole-body postprandial retention of dietary nitrogen, but HC was associated with a faster rate of absorption than was IC, resulting in earlier and stronger hyperaminoacidemia and hyperinsulinemia. An enhancement of both catabolic (26%) and anabolic (37%) utilization of dietary nitrogen occurred in the splanchnic bed at the expense of its further peripheral availability, which reached 18% and 11% of ingested nitrogen 8 h after the IC and HC meals, respectively. Conclusions The form of delivery of dietary AAs constituted an independent factor of modulation of their postprandial regional metabolism, with a fast supply favoring the splanchnic dietary nitrogen uptake over its peripheral anabolic use. These results question a possible effect of ingestion of protein hydrolysates on tissue nitrogen metabolism and accretion. This trial was registered at clinicaltrials.gov as NCT00873951.