Food fortification with multiple micronutrients: impact on health outcomes in general population

Background Vitamins and minerals are essential for growth and maintenance of a healthy body, and have a role in the functioning of almost every organ. Multiple interventions have been designed to improve micronutrient deficiency, and food fortification is one of them. Objectives To assess the impact of food fortification with multiple micronutrients on health outcomes in the general population, including men, women and children. Search methods We searched electronic databases up to 29 August 2018, including the Cochrane Central Register of Controlled Trial (CENTRAL), the Cochrane Effective Practice and Organisation of Care (EPOC) Group Specialised Register and Cochrane Public Health Specialised Register; MEDLINE; Embase, and 20 other databases, including clinical trial registries. There were no date or language restrictions. We checked reference lists of included studies and relevant systematic reviews for additional papers to be considered for inclusion. Selection criteria We included randomised controlled trials (RCTs), cluster‐RCTs, quasi‐randomised trials, controlled before‐after (CBA) studies and interrupted time series (ITS) studies that assessed the impact of food fortification with multiple micronutrients (MMNs). Primary outcomes included anaemia, micronutrient deficiencies, anthropometric measures, morbidity, all‐cause mortality and cause‐specific mortality. Secondary outcomes included potential adverse outcomes, serum concentration of specific micronutrients, serum haemoglobin levels and neurodevelopmental and cognitive outcomes. We included food fortification studies from both high‐income and low‐ and middle‐income countries (LMICs). Data collection and analysis Two review authors independently screened, extracted and quality‐appraised the data from eligible studies. We carried out statistical analysis using Review Manager 5 software. We used random‐effects meta‐analysis for combining data, as the characteristics of study participants and interventions differed significantly. We set out the main findings of the review in 'Summary of findings' tables, using the GRADE approach. Main results We identified 127 studies as relevant through title/ screening, and included 43 studies (48 papers) with 19,585 participants (17,878 children) in the review. All the included studies except three compared MMN fortification with placebo/no intervention. Two studies compared MMN fortification versus iodised salt and one study compared MMN fortification versus cal