Modeled gradual changes in protein intake to increase nutrient adequacy lead to greater sustainability when systematically targeting an increase in the share of plant protein

Abstract

Background. Our diets are undergoing a transition towards a lower consumption of animal protein, in line with the sustainability of diets. Given the differences in nutritional profile between protein sources, changes in consumption, even marginal, raise the question of the nutritional quality of diets. Objectives. Our objective was to identify the consequences, on sustainability parameters, of rearrangements of protein intake aiming at improving nutritional adequacy, depending on whether or not we constrained an increase of the proportion of vegetable proteins. Methods. Based on the consumption data from the INCA2 study (2006-2007), we simulated, for each individual, all possible substitutions of a portion of a protein food for a portion of another protein food, and selected the substitution that increased nutritional adequacy the most (estimated with probabilistic PANDiet score). This step was iterated 20 times for each individual under two different scenarios: by constraining (P) or not (N) an increase in the percentage of plant protein at each iteration. The sustainability parameters studied were diet costs, greenhouse gas emissions (GHGE), exposure to food contaminants and premature deaths avoided (estimated with the PRIME model). Results. The percentage of plant protein (31.1%) decreased slightly in N (30.0%) and increased in P (37.7%). The food groups whose contribution to protein intake increased the most were legumes (+225%), fatty fish (+151%) and lean chicken (+82%) in N and legumes (+502%), pizzas and quiches (+190%) and fatty fish (+102%) in P. The PANDiet increased slightly more in N (+7.5) than in P (+6.2) due to higher probabilities of adequacy in EPA + DHA, iron, iodine, potassium, zinc, riboflavin, vitamin B-6 and B-12 despite lower probabilities of adequacy in fiber and folates. GHGE increased in N and decreased in P. The diet cost increased more in N than in P. Risks related to exposure to inorganic arsenic, dioxins and furans and nickel increased in N and P. The modifications identified could lead to 1,700 and 2,200 premature deaths avoided / year in N and P, respectively. Conclusion. We identified simple modifications of the protein intake that significantly increased the nutritional adequacy of diets. By forcing these changes to systematically increase the proportion of vegetable protein, nutritional adequacy increased less, but the price increased less, the GHGE decreased and deaths avoided increased.