A sustainable diet is, by definition, nutritionally adequate, economically affordable, culturally acceptable, and environmentally respectful. Designing such a diet has to integrate different dimensions of diet sustainability that may not be compatible with each other. Among multicriteria assessment methods, diet optimization is a whole-diet approach that simultaneously combines several metrics for dimensions of diet sustainability. This narrative review based on 67 published studies shows how mathematical diet optimization can help with understanding the relations between the different dimensions of diet sustainability and how it can be properly used to identify sustainable diets. Diet optimization aims to find the optimal combination of foods for a population, a subpopulation, or an individual that fulfills a set of constraints while minimizing or maximizing an objective function. In the studies reviewed, diet optimization was used to examine the links between dimensions of diet sustainability, identify the minimum cost or environmental impact of a nutritionally adequate diet, or identify food combinations able to combine ≥2 sustainability dimensions. If some constraints prove difficult to fulfill, this signals an incompatibility between nutrient recommendations, over-monotonous food-consumption patterns, an inadequate supply of nutrient-rich foods, or an incompatibility with other dimensions. If diet optimization proves successful, it can serve to design nutritionally adequate, culturally acceptable, economically affordable, and environmentally friendly diets. Diet optimization results can help define dietary recommendations, tackle food security issues, and promote sustainable dietary patterns. This review emphasizes the importance of carefully choosing the model parameters (variables, objective function, constraints) and input data and the need for appropriate expertise to correctly interpret and communicate the results. Future research should make improvements in the choice of metrics used to assess each aspect of a sustainable diet, especially the cultural dimension, to improve the practicability of the results.

The European Food Safety Authority (EFSA) states that young child formulae (YCFs) “cannot be considered as a necessity to satisfy the nutritional requirements” of children aged 12–36 months. This study quantifies the dietary changes needed to ensure nutritional adequacy in U.K. young children who consume YCFs and/or supplements and in those who do not. Dietary data from 1147 young children (aged 12–18 months) were used to identify, using linear programming models, the minimum changes needed to ensure nutritional adequacy: (i) by changing the quantities of foods initially consumed by each child (repertoire-foods); and (ii) by introducing new foods (non-repertoire-foods). Most of the children consumed neither YCFs, nor supplements (61.6%). Nutritional adequacy with repertoire-foods alone was ensured for only one child in this group, against 74.4% of the children consuming YCFs and supplement. When access to all foods was allowed, smaller food changes were required when YCFs and supplements were initially consumed than when they were not. In the total sample, the main dietary shifts needed to ensure nutritional adequacy were an increase in YCF and a decrease in cow’s milk (+226 g/day and −181 g/day, respectively). Increasing YCF and supplement consumption was the shortest way to cover the EFSA nutrient requirements of U.K. children.

Background Recent changes in Egyptian dietary habits can be attributed to more urban and sedentary lifestyles and to alterations in the dietary and economic context. The mean BMI of Egyptian women is one of the highest worldwide, and 50% have iron deficiency. Objective The aim was to quantify food and nutrient intakes of urban Egyptian women and conduct a detailed analysis of micronutrients commonly consumed in inadequate amounts, such as iron, vitamin D, and folate. Methods Urban Egyptian women aged 19–30 y (n = 130) were recruited during 2016–2017. Energy needs were estimated using the Henry equation, assuming a low physical activity level (1.4). Dietary intakes and iron bioavailability were estimated from a 4-d food diary. Macronutrient intakes were compared with WHO/FAO population goals and micronutrient intakes with Egyptian recommendations. Iron needs were determined for each subject. Results The mean BMI (kg/m2) was 27.9 ± 4.9. The mean total energy intake (TEI; 2389 ± 715 kcal/d) was significantly higher than needs (2135 ± 237 kcal/d; P = 0.00018). Total fat (33%TEI) and SFA (11%TEI) intakes were slightly higher than population goals (15–30%TEI and <10%TEI, respectively). Diets provided 18 ± 8 g/d of fiber, 98 ± 54 g/d of total sugars, and nearly twice the recommended sodium intake (intake: 2787 ± 1065 mg/d; recommendation: <1500 mg/d). Estimated dietary iron bioavailability was low (9.2% ± 1.6%), and 79% of women consumed less iron than the average requirement (17.5 ± 7 mg/d). Overall, 82% and 80% of women consumed less vitamin D and folate, respectively, than recommended. Conclusions Egyptian women aged 19–30 y have high intakes of energy and sodium, whereas iron, vitamin D, and folate intakes are insufficient, with only low concentrations of bioavailable iron. These results call for further investigation into measures that would improve this population's diet quality.