Scientific Targets for Healthy Diets* Food group Food subgroup Reference diet (g/day) Possible ranges (g/day) Whole Grains All grains 232 0 to 60% of energy Tubers/Starchy Vegetables Potatoes, cassava 50 0 to 100 Vegetables All vegetables 300 200 to 600 Fruits All Fruits 200 100 to 300 Dairy Foods Dairy Foods 250 0 to 500 Beef, lamb, pork 14 0 to 28 Protein Sources Chicken, other poultry 29 0 to 58 Eggs 13 0 to 25 Fish 28 0 to 100 Dry beans, lentils, peas 50 0 to 100 Soy 25 0 to 50 Nuts 50 0 to 75 Added fats Unsaturated oils 40 20-80 Added sugars All sweeteners 31 0 to 31 * See Table 1 for a complete list of scientific targets for a 2500 kcal/day healthy reference diet The Commission has integrated, with the quantification of universal healthy diets, global scientific targets for sustainable food systems. The objective is to provide scientific boundaries to reduce environmental degradation arising from food production at all scales. The quantification of scientific targets for the safe operating space of food systems in the world, was done for the key environmental systems and processes where food production plays a dominant role in determining the state of the planet. There is strong scientific evidence that food production is among the largest drivers of global environmental change due to its contributions to greenhouse gas (GHG) emissions, biodiversity loss, freshwater use, eutrophication, and land-system change (as well as chemical pollution, which is not assessed by this Commission). In turn, food production depends upon the continued functioning of these biophysical systems and processes in regulating and maintaining a stable Earth system. These systems and processes thereby provide a necessary set of globally systemic indicators of what constitutes sustainable food production. The Commission concludes that these quantitative scientific targets for sustainable food systems, constitute universal and scalable planetary boundaries for the food system, (Table 2). However, the uncertainty range for these food boundaries remain high, due to the inherent complexity in Earth system dynamics from local ecosystems to the functioning of the biosphere and the climate system. Scientific Targets for Sustainable Food Production Earth system process Control variable Boundary Uncertainty Range Climate change GHG (CH4 and N2O) emissions 5 Gt CO2-eq yr-1 (4.7-5.4 Gt CO2-eq yr-1) Nitrogen cycling N application 90 Tg N yr-1 (65-90 Tg N yr-1) (90-130 Tg N yr-1) Phosphorus cycling P application 8 Tg P yr-1 (6-12 Tg P yr-1) (8-16 Tg P yr-1) Freshwater use Consumptive water use 2,500 km 3 yr-1 (1000-4000 km 3 yr-1) Biodiversity loss Extinction rate 10 E/MSY (1-80 E/MSY) Land-system change Cropland use 13 M km 2 (11-15 M km 2)

The aim of this study was to evaluate the reproducibility and validity of a 61-item semiquantitative food frequency questionnaire used in a large prospective study among women. This form was administered twice to 173 participants at an interval of approximately one year (1980-1981), and four one-week diet records for each subject were collected during that period. Intraclass correlation coefficients for nutrient intakes estimated by the one-week diet records (range = 0.41 for total vitamin A without supplements to 0.79 for vitamin B6 with supplements) were similar to those computed from the questionnaire (range = 0.49 for total vitamin A without supplements to 0.71 for sucrose), indicating that these methods were generally comparable with respect to reproducibility. With the exception of sucrose and total carbohydrate, nutrient intakes from the diet records tended to correlate more strongly with those computed from the questionnaire after adjustment for total caloric intake. Correlation coefficients between the mean calorie-adjusted intakes from the four one-week diet records and those from the questionnaire completed after the diet records ranged from 0.36 for vitamin A without supplements to 0.75 for vitamin C with supplements. Overall, 48% of subjects in the lowest quintile of calorie-adjusted intake computed from the diet records were also in the lowest questionnaire quintile, and 74% were in the lowest one of two questionnaire quintiles. Similarly, 49% of those in the highest diet record quintile were also in the highest questionnaire quintile, and 77% were in the highest one or two questionnaire quintiles. These data indicate that a simple self-administered dietary questionnaire can provide useful information about individual nutrient intakes over a one-year period.

In epidemiologic studies, total energy intake is often related to disease risk because of associations between physical activity or body size and the probability of disease. In theory, differences in disease incidence may also be related to metabolic efficiency and therefore to total energy intake. Because intakes of most specific nutrients, particularly macronutrients, are correlated with total energy intake, they may be noncausally associated with disease as a result of confounding by total energy intake. In addition, extraneous variation in nutrient intake resulting from variation in total energy intake that is unrelated to disease risk may weaken associations. Furthermore, individuals or populations must alter their intake of specific nutrients primarily by altering the composition of their diets rather than by changing their total energy intake, unless physical activity or body weight are changed substantially. Thus, adjustment for total energy intake is usually appropriate in epidemiologic studies to control for confounding, reduce extraneous variation, and predict the effect of dietary interventions. Failure to account for total energy intake can obscure associations between nutrient intakes and disease risk or even reverse the direction of association. Several disease-risk models and formulations of these models are available to account for energy intake in epidemiologic analyses, including adjustment of nutrient intakes for total energy intake by regression analysis and addition of total energy to a model with the nutrient density (nutrient divided by energy).