This website was created to centralize important information regarding the methodology to attribute nutrition values to the foods listed in the different datasets.
We will share here our discussions, decisions and relevant files to document the process and serve as an archive for future improvements in the datasets. The key aspects that will be discussed in the next few months include:
One of the data types included in the Food and Diet Domain is the Supply Utilization Accounts (SUAs). The SUAs provide, per country, the balance between supplied and utilized quantities of a food (= utilized food), during a calendar year, including agricultural and fishery sectors (for more details click here).
The SUAs dataset covers about 450 food items for crops and livestock food products (excluding fishery).
For the SUAs data, it was decided that four nutrient conversion tables (NCT) should be prepared: (1) a regional NCT for African countries; (2) a regional NCT for Asean countries; and (3) a regional table for Latin America; and (4) a Global NCT for the remaining countries. The Global NCT will be prepared in 2021 and the three regional NCTs will be part of the second phase of the project in 2022.
Each NCT will be prepared by matching the list of food items from SUAs to data available in selected Food Composition Tables published at national, regional to global level.
To assist on the selection of the FCT/FCDBs for use, the group agreed that the new FAO/INFOODS Evaluation Framework was used as a criteria to assess the quality of the potential FCT/FCDBs.
Thus, some FCT/FCDBs where suggested by the team and assessed according to the eight screening questions available in the FAO/INFOODS Evaluation Framework. If the score for a certain FCT/FCDB was >100 it was considered as a possible source of data for the Nutrient Conversion Tables that will be prepared to convert the data from SUA and HCES datasets.
NOTE: There were two exceptions: (1) the Indian Food Composition Tables was selected for use (score = 90). Even though the score below FAO/INFOODS recommendations, it will be selected for use since it fits to the purpose of the project. The main points lost were due to: data is not available in Excel (but we have it); it includes raw foods only (we will not use cooked foods). (2) the Food Composition Table for Central and Eastern Uganda because its primary data source is the USDA database (already included in our selection) and when the food was not available in the USDA table they used mostly tables from the 90’s to borrow the nutrient values (high possibility to include obsolete analytical data).
Quality assessment of selected FCT/FCDB using the screening questions of the FAO/INFOODS Evaluation Framework.
How to evaluate the quality of food composition data and food composition tables?
Edible portion (EP) represent the parts of food item that can be eaten, after removing any inedible portions (e.g. seeds, peel, shells, bone and skin). The portion of the food that is inedible is called the “refuse”. Since the whole amount of food available for consumption is recorded in the SUA and HCES datasets and many foods contain an inedible part, this must be taken into account in the calculation of the nutrients available in the food supply. If the weight of the inedible part of the food is not subtracted, supply of nutrients in the foods would be overestimated. The refuse portion may be expressed as a percentage (or as a coefficient) of the total weight of the item as purchased or produced, and is used to compute the weight of the edible portion.
The edible factors prepared by ESN in 2012, presented as a coefficient, will be revised and will be applied to SUAs/fish and HCES data.
However, it is important to note that for some foods reported in the SUAs list, two different types of edible portion will be needed:
For more specific issues on the attribution of the EP coefficients, please refer to the document “Establishing default edible coefficients – specific situations“
The Nutrient Conversion Tables will include energy (kcal), water, total protein, total fat, available carbohydrates calculated by difference, total dietary fiber, alcohol and ash. Energy and available carbohydrates will be calculated according to the following formulas:
Note 1: if the value calculated for CHOAVLDF is negative (<0), it should be set to 0 (zero) before calculating the energy. For further derails please refer to the item “Assumptions for specific foods and components“)
Note 2: the sum of proximate components (SOP) as presented in the original sources and in the final foods should be used as a quality control. If the SOP is outside the acceptable range (95-105) the data for the given food should not be used.
Minerals and vitamins will be selected according to the following criteria:
To assist the evaluation of the FCT/FCDBs regarding item 1, an Excel file listing the main components included, according to the different tagnames was prepared for the FCT/FCDBs selected according to the quality score (available for download in “references and files” below).
Significant digits and decimal places for each component in the nutrient analytical file and for presenting the statistics
The number of significant digits will be based on Greenfield and Southgate (2003), and the number of decimal places will be based on the criteria used in the FAO/INFOODS FCT for Western Africa. An excel file with this information is also available here.
This file list the main components included, according to the different tagnames, in selected FCT/FCDBs.
This file lists the number of significant digits and decimal places to the nutrient analytical file and for presenting the statistics
The importance of component identification; key aspects to check before using food composition data; using the FAO/INFOODS component identifiers (tagnames) for a precise identification
The excel file includes a couple of examples for each methodology. You can download the file to check how we should proceed in each methodology and also to have an idea about the impact in the results. In the video below you will find some details about this file.
Methodologies to convert food amounts into nutrients (with examples)
INFOODS developed these guidelines for a more harmonized approach to food matching while pointing out critical steps and information in order to achieve the most appropriate food matching. These guidelines are intended to assist in selecting the most appropriate foods (for which compositional data are available) to match to foods reported in food consumption surveys (at individual, household, national or international level) or to food supply data (e.g. FAOSTAT, EUROSTAT).
Specific criteria used for SUAs data
Basic principles for the compilation of the Global Nutrient Conversion Table for SUAs
Main files used to compile the Global Nutrient Conversion Table for SUAs
Practical example: matching foods and calculating the average nutrient profile for SUAs
Definition and challenges; FAO/INFOODS guidelines for Food Matching
Created by Fernanda Grande (2021). The content of this website is continuously reviewed and updated.
Last updated 11.11.2021