Healthy diets can create environmental trade-offs, depending on how diet quality is measured

Abstract

Background There is an urgent need to assess the linkages between diet patterns and environmental sustainability in order to meet global targets for reducing premature mortality and improving sustainable management of natural resources. This study fills an important research gap by evaluating the relationship between incremental differences in diet quality and multiple environmental burdens, while also accounting for the separate contributions of retail losses, inedible portions, and consumer waste. Methods Cross sectional, nationally-representative data on food intake in the United States were acquired from the National Health and Nutrition Examination Survey (2005–2016), and were linked with nationally-representative data on food loss and waste from published literature. Survey-weighted procedures estimated daily per capita food retail loss, food waste, inedible portions, and consumed food, and were summed to represent Total Food Demand. Diet quality was measured using the Healthy Eating Index-2015 and the Alternative Healthy Eating Index-2010. Data on food intake, loss, and waste were inputted into the US Foodprint Model to estimate the amount of agricultural land, fertilizer nutrients, pesticides, and irrigation water used to produce food. Results This study included dietary data from 50,014 individuals aged ≥2 y. Higher diet quality (HEI-2015 and AHEI-2010) was associated with greater per capita Total Food Demand, as well as greater retail loss, inedible portions, consumer waste, and consumed food (P < 0.001 for all comparisons). Consumed food accounted for 56–74% of agricultural resource use (land, fertilizer nutrients, pesticides, and irrigation water), retail loss accounted for 4–6%, inedible portions accounted for 2–15%, and consumer waste accounted for 20–23%. Higher diet quality was associated with lower use of agricultural land, but the relationship to other agricultural resources was dependent on the tool used to measure diet quality (HEI-2015 vs. AHEI-2010). Conclusions Over one-quarter of the agricultural inputs used to produce Total Food Demand were attributable to edible food that was not consumed. Importantly, this study also demonstrates that the relationship between diet quality and environmental sustainability depends on how diet quality is measured. These findings have implications for the development of sustainable dietary guidelines, which requires balancing population-level nutritional needs with the environmental impacts of food choices.

Food Waste and Nutrition Quality in the Context of Public Health: A Scoping Review

“…A range of publication types were included in this review, including 10 cross-sectional studies [ 58 , 59 , 60 , 61 , 62 , 63 , 64 , 65 , 66 , 67 ], one review [ 68 ], two systematic reviews [ 69 , 70 ], two case studies [ 71 , 72 ], seven intervention studies (three non-randomized controlled trials [ 73 , 74 , 75 ], one randomized controlled trial [ 76 ], three pre-post-design studies [ 77 , 78 , 79 ]), one observational study [ 80 ], one comparative analysis [ 81 ], one critical evaluation [ 82 ], one time series [ 83 ], one multi-method study [ 84 ], and six food-based dietary guidelines [ 85 , 86 , 87 , 88 , 89 , 90 ]. Four main concepts were mapped from the resulting data ( Figure 3 ), and the publications were grouped into these concepts as appropriate.…”

“…Food waste measurements ranged from 107 g–422 g per capita per day, 65–110 kg per capita per year, [ 59 , 61 , 62 , 64 ], and 2.98 kg per week [ 80 ]. Six studies analyzed food waste at consumer level [ 58 , 59 , 61 , 62 , 64 , 80 ] and two studies analyzed food waste at retail and consumer levels [ 60 , 63 ]. Six studies assessed the nutritional losses embedded in wasted food, with quantities of wasted nutrients varying significantly between studies and different nutrients being identified as the most wasted [ 58 , 61 , 62 , 63 , 64 , 80 ].…”

Sustainability Indicators for Foods Benefiting Climate and Health

“…However, the usefulness of nutrient density scores, used separately or in combination with environmental assessment, is today greatly limited by the lack of harmonization and guiding principles for the use of methods. Many different methods for calculating nutrient density of food products exist [13,15,17,25] and choice of index and how it is integrated with environmental assessments can greatly affect the conclusions regarding which foods are more and less sustainable to consume [13,32]. Here, our results demonstrate how two different approaches for performing combined analyses of nutrient density and climate impact, parallel and integrated, and encompassed method choices, e.g., choice of functional unit expressing climate impact of foods, have important implications for food subgroup categorization and ranking.…”

Standardized Recipes and Their Influence on the Environmental Impact Assessment of Mixed Dishes: A Case Study on Pizza

“…Compared to the SR, the approach seemed to overestimate dairy, sugars, and vegetables and it does not consider water as an ingredient. The FCID, which has been used before as a food decomposition method [17,18,41,42], offers a satisfactory ingredient resolution and matching with LCIs, except for dairy. An important limitation of this approach is that it is unable to distinguish between dairy ingredients (e.g., milk, cheese, and yogurt) in the food [17].…”

“…As many food contain multiple dairy ingredients and the environmental footprints of dairy products vary considerably [43], using FCID to decompose foods into ingredients is problematic for many food and diet evaluations. Another limitation of the FCID and FICRCD databases is that they have not been updated for nearly 10 years [41]. Consequently, the two approaches cannot be used in the evaluation of foods introduced in the newer cycles of NHANES, as evident from the 20+ pizzas missing from our analysis using these approaches.…”