The Food and Agriculture Organization defines sustainable diets as nutritionally adequate, safe, healthy, culturally acceptable, economically affordable diets that have little environmental impact. This review summarizes the studies assessing, at the individual level, both the environmental impact and the nutritional quality or healthiness of self-selected diets. Reductions in meat consumption and energy intake were identified as primary factors for reducing diet-related greenhouse gas emissions. The choice of foods to replace meat, however, was crucial, with some isocaloric substitutions possibly increasing total diet greenhouse gas emissions. Moreover, nutritional adequacy was rarely or only partially assessed, thereby compromising the assessment of diet sustainability. Furthermore, high nutritional quality was not necessarily associated with affordability or lower environmental impact. Hence, when identifying sustainable diets, each dimension needs to be assessed by relevant indicators. Finally, some nonvegetarian self-selected diets consumed by a substantial fraction of the population showed good compatibility with the nutritional, environmental, affordability, and acceptability dimensions. Altogether, the reviewed studies revealed the scarcity of standardized nationally representative data for food prices and environmental indicators and suggest that diet sustainability might be increased without drastic dietary changes.

Objective: To assess the compatibility between reduction of diet-related greenhouse gas emissions (GHGE) and nutritional adequacy, acceptability and affordability dimensions of diet sustainability.Design: Dietary intake, nutritional composition, GHGE and prices were combined for 402 foods selected among those most consumed by participants of the Individual National Study on Food Consumption. Linear programming was used to model diets with stepwise GHGE reductions, minimized departure from observed diet and three scenarios of nutritional constraints: none (FREE), on macronutrients (MACRO) and for all nutrient recommendations (ADEQ). Nutritional quality was assessed using the mean adequacy ratio (MAR) and solid energy density (SED).Setting: France.Subjects: Adults (n 1899).Results: In FREE and MACRO scenarios, imposing up to 30 % GHGE reduction did not affect the MAR, SED and food group pattern of the observed diet, but required substitutions within food groups; higher GHGE reductions decreased diet cost, but also nutritional quality, even with constraints on macronutrients. Imposing all nutritional recommendations (ADEQ) increased the fruits and vegetables quantity, reduced SED and slightly increased diet cost without additional modifications induced by the GHGE constraint up to 30 % reduction; higher GHGE reductions decreased diet cost but required non-trivial dietary shifts from the observed diet. Not all the nutritional recommendations could be met for GHGE reductions ≥70 %.Conclusions: Moderate GHGE reductions (≤30 %) were compatible with nutritional adequacy and affordability without adding major food group shifts to those induced by nutritional recommendations. Higher GHGE reductions either impaired nutritional quality, even when macronutrient recommendations were imposed, or required non-trivial dietary shifts compromising acceptability to reach nutritional adequacy.

Breakfast is often referred to as the most important meal of the day and in recent years has been implicated in weight control, cardio-metabolic risk factors and cognitive performance although, at present, the literature remains inconclusive as to the precise health benefits of breakfast. There are extensive reports of breakfast’s contributions to daily food and nutrient intakes, as well as many studies that have compared daily food and nutrient intakes by breakfast consumers and skippers. However, significant variation exists in the definitions of breakfast and breakfast skippers, and in methods used to relate breakfast nutrient intakes to overall diet quality. The present review describes a novel and harmonised approach to the study of the nutritional impact of breakfast through The International Breakfast research Initiative involving national dietary survey data from Canada, Denmark, France, Spain, the UK and the USA. It is anticipated that the analysis of such data along harmonised lines, will allow the project to achieve its primary goal of exploring approaches to defining optimal breakfast food and nutrient intakes. Such data will be of value to public health nutrition policy-makers and food manufacturers and will also allow consistent messaging to help consumers to optimize food choices at breakfast.

Studies on theoretical diets are not sufficient to implement sustainable diets in practice because of unknown cultural acceptability. In contrast, self-selected diets can be considered culturally acceptable. The objective was to identify the most sustainable diets consumed by people in everyday life. The diet-related greenhouse gas emissions (GHGE) for self-selected diets of 1918 adults participating in the cross-sectional French national dietary survey Individual and National Survey on Food Consumption (INCA2) were estimated. "Lower-Carbon," "Higher-Quality," and "More Sustainable" diets were defined as having GHGE lower than the overall median value, a probability of adequate nutrition intake (PANDiet) score (a measure of the overall nutritional adequacy of a diet) higher than the overall median value, and a combination of both criteria, respectively. Diet cost, as a proxy for affordability, and energy density were also assessed. More Sustainable diets were consumed by 23% of men and 20% of women, and their GHGE values were 19% and 17% lower than the population average (mean) value, respectively. In comparison with the average value, Lower-Carbon diets achieved a 20% GHGE reduction and lower cost, but they were not sustainable because they had a lower PANDiet score. Higher-Quality diets were not sustainable because of their above-average GHGE and cost. More Sustainable diets had an above-average PANDiet score and a below-average energy density, cost, GHGE, and energy content; the energy share of plant-based products was increased by 20% and 15% compared with the average for men and women, respectively. A strength of this study was that most of the dimensions for "sustainable diets" were considered, ie, not only nutritional quality and GHGE but also affordability and cultural acceptability. A reduction in diet-related GHGE by 20% while maintaining high nutritional quality seems realistic. This goal could be achieved at no extra cost by reducing energy intake and energy density and increasing the share of plant-based products.

Sustainable diets, as defined by the Food and Agriculture Organization, need to combine environment, nutrition, and affordability dimensions. However, it is unknown whether these dimensions are compatible, and no guidance is available in the official recommendations. To identify foods with compatible sustainability dimensions. For 363 of the most commonly consumed foods in the Second French Individual and National Study on Food Consumption, environmental impact indicators (ie, greenhouse gas [GHG] emissions, acidification, and eutrophication), and prices were collected. The nutritional quality of the foods was assessed by calculating the score for the nutritional adequacy of individual foods (SAIN) to score for disqualifying nutrients (LIM) ratio. A sustainability score based on the median GHG emissions, price, and SAIN:LIM was calculated for each food; the foods with the best values for all three variables received the highest score. The environmental indicators were strongly and positively correlated. Meat, fish, and eggs and dairy products had the strongest influence on the environment; starchy foods, legumes, and fruits and vegetables had the least influence. GHG emissions were inversely correlated with SAIN:LIM (r=-0.37) and positively correlated with price per kilogram (r=0.59); the correlation with price per kilocalorie was null. This showed that foods with a heavy environmental impact tend to have lower nutritional quality and a higher price per kilogram but not a lower price per kilocalorie. Using price per kilogram, 94 foods had a maximum sustainability score, including most plant-based foods and excluding all foods with animal ingredients except milk, yogurt, and soups. Using price per kilocalorie restricted the list to 42 foods, including 52% of all starchy foods and legumes but only 11% of fruits and vegetables (mainly 100% fruit juices). Overall, the sustainability dimensions seemed to be compatible when considering price per kilogram of food. However, this conclusion is too simplistic when considering price per kilocalorie, which highlights the need to integrate the data at the diet level.

Few prospective studies have examined the effects of different types of dairy food on the risks of type 2 diabetes, CHD and mortality. We examined whether intakes of total dairy, high-fat dairy, low-fat dairy, milk and fermented dairy products were related to these outcomes in the Whitehall II prospective cohort study. At baseline, dairy consumption was assessed by FFQ among 4526 subjects (72 % men) with a mean age 56 (sd 6) years. Death certificates and medical records were used to ascertain CHD mortality and non-fatal myocardial infarction. Incident diabetes was detected by the oral glucose tolerance test or self-report. Incidence data were analysed using Cox proportional hazards models, adjusted for lifestyle and dietary factors. During approximately 10 years of follow-up, 273 diabetes, 323 CHD and 237 all-cause mortality cases occurred. In multivariable models, intakes of total dairy and types of dairy products were not significantly associated with incident diabetes or CHD (all P values for trend >0·1). Fermented dairy products was inversely associated with overall mortality (hazard ratios approximately 0·7 in the middle and highest tertiles; P for trend < 0·01) but not with incident CHD or diabetes (P>0·3). In conclusion, intakes of total dairy and types of dairy products showed no consistent relationship with incident diabetes, CHD or all-cause mortality.