5. Characteristics of included systematic reviews: adolescent children (aged 11 to 18 years).

Review	Date of search	Number of included trials (number of participants included)	Review question/objective	Trial designs included	Participants	Setting, anaemia and malaria prevalence	Intervention and comparison	Relevant outcomes (definition used in the review, adjusted for smoking and altitude)	GRADE assessment of relevant outcomes Method used to assess risk of bias and summary
Supplementation
Fernández‐Gaxiola 2019 Intermittent iron supplementation for reducing anaemia and its associated impairments in adolescent and adult menstruating women	February 2018	25 trials (10,996 women)	To assess the effects of intermittent oral iron supplementation, alone or in combination with other nutrients, on anaemia and its associated impairments in menstruating women, compared with no intervention, a placebo or daily supplementation	RCTs Quasi‐RCTs Cluster‐RCTs	Menstruating women, that is women beyond menarche and prior to menopause who are not pregnant or lactating or have any condition that impedes the presence of menstrual periods, regardless of their baseline iron status/anaemia status, ethnicity, country of residence or level of endurance. (> 60% of the included trials included women under 18 years)	LMIC (15 trials) Europe (1 trial) Latin America (4 trials) Africa (5 trials) Asia (15 trials) Malaria: 5 trials conducted in endemic areas Anaemia prevalence: 1 trial prevalent, but percentage not reported	Intervention: intermittent dosage of iron alone or with other vitamins and minerals Comparison: placebo or no intervention or the same supplements provided on a daily basis	Hb (g/L) Anaemia (Hb concentration below a cut‐off defined by trialists, adjusted by altitude and smoking as appropriate) IDA (defined by the presence of anaemia plus ID diagnosed with an indicator of iron status selected by trialists) ID (defined by trialists using indicators of iron status such as ferritin or transferrin) Any adverse side effects (e.g. nausea, vomiting, constipation, gastrointestinal discomfort, as defined by the trialists) Adjustments: not reported	GRADE: intermittent iron supplementation versus no supplementation or placebo: Hb = moderate, anaemia = low IDA = low, ID = low, any adverse side effects = moderate; intermittent iron supplementation versus daily iron: Hb = low, anaemia = moderate, IDA = no trials, ID = very low, any adverse side effects = low Cochrane RoB 1 tool Overall, most trials (23/25) were considered to be at high risk of bias due to lack of description of methods used for randomisation and allocation concealment and lack of blinding
Neuberger 2016 Oral iron supplements for children in malaria‐endemic areas	MEDLINE (August 2015); Other databases (February 2015)	35 trials (31,955 children)	To evaluate the effects and safety of iron supplementation, with or without folic acid, in children living in areas with hyperendemic or holoendemic malaria transmission	RCTs Cluster‐RCTs	Children (less than 18 years of age), with or without anaemia, and with or without malaria or parasitaemia	Areas that are malaria‐endemic, and where children may benefit from iron treatment; the baseline rate of malaria parasitaemia (reported in 11 of 19 trials) ranged from 0% to 70% of children (mean 45%) Anaemia prevalence: not reported	Intervention: iron supplementation, with or without folic acid or antimalarial treatment Comparison: placebo or no treatment or antimalarial treatment (only when the intervention is iron plus antimalarial)	Hb (g/dL) Anaemia as defined in trial Adjustments: not reported	GRADE: not assessed The quality of studies was assessed by the Cochrane RoB 1 tool; subgroup analyses performed. Publication bias assessed by funnel plots. Around 57% of studies were at low risk of bias related to allocation concealment, 74.5% of studies to random sequence generation, and 77.1% to blinding.
Salam 2016 Interventions to improve adolescent nutrition: a systematic review and meta‐analysis	December 2014	31 trials (MN supplementation) 10 trials (nutrition in pregnant adolescents)	To ascertain the effectiveness of interventions to promote nutrition among adolescents comprising of MN supplementation, nutrition interventions for pregnant adolescents, and interventions to prevent obesity	RCTs Quasi‐RCTs CBA trials	Adolescent population (11 to 19 years old) Low‐income, pregnant adolescents (13 to 20 years old) (only data for adolescent population was extracted)	MN supplementation: 23/31 trials conducted in LMICs Nutrition in pregnancy: prenatal clinics in urban areas in Chile, Ecuador, USA, Canada Anaemia and malaria prevalence: not reported	Interventions: interventions to promote nutrition among adolescent (e.g. micronutrient supplementation, nutrition in pregnancy) Comparison: control (not specified)	Hb (g/L) Anaemia (as defined by trial authors) IDA Adjustments: not reported	GRADE: MN supplementation: anaemia = moderate; nutrition in pregnancy: anaemia = low, other outcomes = not assessed Cochrane RoB 1 tool, but only GRADE is reported
Salam 2020 Effects of preventive nutrition interventions among adolescents on health and nutritional status in low‐ and middle‐income countries	February 2019	10 studies (10,802 adolescents)	To assess the impact of preventive nutrition interventions on health and nutritional status of adolescents aged 10 to 19 years in LMICs	RCTs Cluster‐RCTs Quasi‐RCTs CBA ITS	Adolescents aged 10 to 19 years	School setting in LMICs: China, India, Sri Lanka, Bangladesh, Indonesia Anaemia and malaria prevalence: not reported	Intervention: MN supplementation/fortification Comparison: placebo/no supplementation/no fortification	Anaemia; adjustment: not reported	GRADE: anaemia = low Study quality assessed by Cochrane RoB 1 tool for RCTs and EPOC risk of bias tool for non‐randomised studies. The included studies were judged to be at unclear risk of bias due to insufficient information regarding sequence generation, allocation concealment, and selective reporting.

CBA: controlled before‐and‐after trials; EPOC: Effective Practice and Organisation of Care; Hb: haemoglobin; ID: iron deficiency; IDA: iron deficiency anaemia; ITS: interrupted time series; LMICs: low‐ and middle‐income countries; MN: micronutrient; RCTs: randomised controlled trials.