Approximately Half of Total Protein Intake by Adults Must be Animal-Based to Meet Nonprotein, Nutrient-Based Recommendations, With Variations Due to Age and Sex

Abstract

Shifting towards a more plant-based diet, as promoted in Western countries, will reduce the animal protein contribution to total proteins. Such a reduction may not only impair protein adequacy, but also the adequacy in other nutrients. We determined, for different adult subpopulations, the minimum total protein levels and the minimum animal protein contributions to total proteins that are compatible with the fulfillment of all nonprotein nutrient-based recommendations. Mean nutritional contents and mean diet costs were estimated using a French, cross-sectional, representative survey for 5 French subpopulations: 1) women < 50 y; 2) women 50-64 y; 3) women ≥ 65 y; 4) men < 65 y; and 5) men ≥ 65 y. For each subpopulation, linear programming optimization was used to assess the minimum protein level (model set #1) and the minimum animal protein contribution to total proteins (model set #2) that are compatible with the fulfillment of all nutrient-based recommendations (except proteins, for which levels were analyzed as outputs). Total diet costs were not allowed to increase. Eating habits were considered in model set #2 only. The minimum amount of protein that was theoretically compatible with the fulfillment of nutrient-based recommendations (model set #1) was below the minimum recommended protein intake for all subpopulations except women < 50 y. In model set #2, for women and men ≥ 65 y, decreasing animal protein contributions to total proteins below 55% and 60%, respectively, led to protein levels below recommended levels. For the other subpopulations (women < 50 y, women 50-64 y, and men < 65 y), the lowest animal protein contributions to total proteins compatible with a nutritionally adequate diet (including protein adequacy) were 55%, 50%, and 45%, respectively. This study provides factual information about the animal protein contributions to total proteins compatible with meeting all nutrient-based recommendations at no additional cost, and shows that they vary between 45% and 60% depending on the group of adults considered.