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FAOSTAT Food and Diet Domain

- METHODOLOGY TO ATTRIBUTE NUTRITION VALUES TO FOODS -

Background

FAOSTAT Food and Diet Domain

Given the importance of dietary data to guide food systems policies, the Food Security and Nutrition Statistics Team (ESS) and the Food and Nutrition Division (ESN) are collaborating in a joint effort to help reducing the significant dietary statistics gap and to strengthen the synchronization of available data sources.
 
The Food and Diet Domain Project aims to harmonize the processing of dietary data, to increase the dissemination and improve utilization of comparable food availability, food consumption, and diet quality statistics and indicators. 
 
This initiative will bring together, for the first time, data from individual food consumption surveys, women’s dietary diversity, Household Consumption and Expenditure Surveys (HCES), Supply Utilization Accounts (SUA) and Food Balance Sheets (FBS); and disseminate them through a common “Food and Diet” domain on FAOSTAT. 
 
Linking these data to food composition data is one of the key steps required prior to the dissemination through the domain. Therefore, preparing the “Nutrient Conversion Tables” (NCT) will require discussions among the team members to establish a standardized procedure to be applied to all datasets.

About the website

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:

Supply Utilization Accounts (SUAs)

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.

Selection of Food Composition Tables and Components

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).

References and files

Quality assessment of selected FCT/FCDB using the screening questions of the FAO/INFOODS Evaluation Framework.

Background information

Play Video

FAO/INFOODS Evaluation Framework

 How to evaluate the quality of food composition data and food composition tables?

If needed you can access the original data and documentation for our Reference Datasets in the links below

  • FAO/INFOODS Food Composition Table for Western Africa (link)
  • Kenya Food Composition Tables  (link)
  • Indian Food Composition Tables (link)
  • FAO/INFOODS Global Food Composition Database for Pulses (link)
  • FAO/INFOODS Global Food Composition Database for Fish and Shellfish (link)
  • Australian Food Composition Database (link)
  • Frida DTU Foods public food database (Denmark) (link)
  • USDA National Nutrient Database for Standard Reference – Legacy version (link)
  • New Zealand Food Composition Database (link)
  • Food Data Central of U.S. Department of Agriculture (link)
  • Standard Tables of Food Composition in Japan (link)
  • McCance and Widdowson’s composition of foods integrated dataset (link)
  • Food Composition Table for Bangladesh (link)
  • Brazilian Food Composition Table (TACO), 2011 (link)

Selection of Components

Edible portion/refuse

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:

  • Foods which the weight is recorded as purchased (e.g. fruits, vegetables), the edible coefficient from the FCTs can be correctly used in order to convert the as purchased weight to the edible weight.
  • Foods which the weigh is recorded as produced because these commodities are unlikely to be purchased in this form by the consumer (e.g. meat carcasses and some cereals with husks). Thus it is necessary to establish edible coefficients specific to FAOSTAT for such food items in order to calculate the edible portion. For this foods, when possible, the values should be obtained from the FCL Commodity Trees, World Average in recent years.

For more specific issues on the attribution of the EP coefficients, please refer to the document “Establishing default edible coefficients – specific situations“

Macronutrients

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:

  • Energy (kJ/100 g EP) = total protein (g/100 g EP) × 17 + total fat (g/100 g EP) × 37 + available carbohydrate (g/100 g EP) × 17 + total dietary fibre (g/100 g EP) × 8 + alcohol (g/100 g EP) × 29
  • Energy (kcal/100 g EP) = total protein (g/100 g EP) × 4 + total fat (g/100 g EP) × 9 + available carbohydrate (g/100 g EP) × 4 + total dietary fibre (g/100 g EP) × 2 + alcohol (g/100 g EP) × 7
  • CHOAVLDF (g/100 g EP) = 100 – (water + total fat + total protein + ash + total dietary fibre + alcohol) (g/100 g EP)

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.

  • Sum of proximate components (g/100 g EP) = water (g/100 g EP) + total fat (g/100 g EP) + available carbohydrate (g/100 g EP) + total protein (g/100 g EP) + ash (g/100 g EP) + total dietary fibre (g/100 g EP) + alcohol (g/100 g EP)

Micronutrients

Minerals and vitamins will be selected according to the following criteria:

  1. Availability and compatibility in the selected FCT/FCDBs
  2. Accuracy of the nutrient data in FCTs and estimates (e.g. iodine/sodium)
  3. Public health relevance (nutrient of importance, prevalence of deficiencies)

 

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.

References and files

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

Background information

Component identification - Tagnames

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

Methodology for Calculations

Before starting the preparation of the Nutrient Conversion Tables, it is important to define the methodology that should be used in the calculations.
 
To assist the team in this decision, a couple of examples were prepared in the excel file available below. In this file, it is possible 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 namely “Calculation Methodologies” you will also find important concepts and an explanation about the excel file.
 
The working group decided that the nutrient profile in the NCTs should be expressed per 100g of edible portion of food and that the inedible part should be deducted from the respective total food amount before converting it into nutrient availability.

References and files

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.

Play Video

Calculation Methodologies

Methodologies to convert food amounts into nutrients (with examples)

Food Matching

References and files

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

Complementary videos

Play Video

Basic Principles

Basic principles for the compilation of the Global Nutrient Conversion Table for SUAs

Play Video

Compilation Files

Main files used to compile the Global Nutrient Conversion Table for SUAs

Play Video

Example

Practical example: matching foods and calculating the average nutrient profile for SUAs

Background information

Food Matching

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