Global Coverage of Mandatory Large-Scale Food Fortification Programs: A Systematic Review and Meta-Analysis

Abstract

Food fortification with micronutrients is widely implemented to reduce micronutrient deficiencies and related outcomes. Although many factors affect the success of fortification programs, high population coverage is needed to have a public health impact. We aimed to provide recent global coverage estimates of salt, wheat flour, vegetable oil, maize flour, rice, and sugar among countries with mandatory fortification legislation. The indicators were the proportion of households consuming the: food, fortifiable food (that is, industrially processed), fortified food (to any extent), and adequately fortified food (according to national or international standards). We estimated the number of individuals reached with fortified foods. We systematically retrieved and reviewed all applicable evidence from: published reports and articles from January 2010 to August 2021, survey lists/databases from key organizations, and reports/literature received from key informants. We analyzed data with R statistical package using random-effects meta-analysis models. An estimated 94.4% of households consumed salt, 78.4% consumed fortified salt (4.2 billion people), and 48.6% consumed adequately fortified salt in 64, 84, and 31 countries, respectively. Additionally, 77.4% of households consumed wheat flour, 61.6% consumed fortifiable wheat flour, and 47.1% consumed fortified wheat flour (66.2 million people) in 15, 8, and 10 countries, respectively, and 87.0% consumed vegetable oil, 86.7% consumed fortifiable oil, and 40.1% consumed fortified oil (123.9 million people) in 10, 7, and 5 countries, respectively. Data on adequately fortified wheat flour and vegetable oil and coverage indicators for maize flour, rice, and sugar were limited. There are major data gaps on fortification coverage for most foods except salt. All countries with mandatory fortification programs should generate and use more coverage data to assess program performance and adjust programs as needed to realize their potential to reduce micronutrient deficiencies (PROSPERO CRD42021269364).

Keywords: coverage; fortification; maize; rice; salt; sugar; vegetable oil; wheat flour.

FIGURE 1

PRISMA flowchart of the literature search for selection and inclusion of articles and reports. ASP; DHS, Demographic and Health Survey; GAIN, Global Alliance for Improved Nutrition; GFDx, Global Fortification Data Exchange; IGN, Iodine Global Network; iZiNCG, international Zinc Nutritional Consultancy Group; MICS, Multiple Indicator Cluster Survey; VMNIS, Vitamin and Mineral Nutrition Information System.

FIGURE 2

The availability of coverage data collected between 2010 and 2021 among countries with mandatory food fortification legislation as of June 2021. Number of countries with mandatory food fortification legislation included: salt, n = 125; wheat flour, n = 91; vegetable oil, n = 32; maize flour, n = 19; sugar, n = 12, and rice, n = 7. Coverage data included any of the following indicators: the proportion of households consuming the: 1) food (in any form), 2) fortifiable food (that is, industrially or centrally processed), 3) fortified food (that is, fortified to any extent), and 4) adequately fortified food (that is, fortified in accordance with national or international fortification standards).