Efeito da fortificação de alimentos com ferro sobre anemia em crianças: um estudo de revisão

Wheat flour fortification with iron and other micronutrients for reducing anaemia and improving iron status in populations

BACKGROUND

Anaemia is a condition where the number of red blood cells (and consequently their oxygen-carrying capacity) is insufficient to meet the body's physiological needs. Fortification of wheat flour is deemed a useful strategy to reduce anaemia in populations.

OBJECTIVES

To determine the benefits and harms of wheat flour fortification with iron alone or with other vitamins and minerals on anaemia, iron status and health-related outcomes in populations over two years of age.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, CINAHL, 21 other databases and two trials registers up to 21 July 2020, together with contacting key organisations to identify additional studies.

SELECTION CRITERIA

We included cluster- or individually-randomised controlled trials (RCTs) carried out among the general population from any country, aged two years and above. The interventions were fortification of wheat flour with iron alone or in combination with other micronutrients. We included trials comparing any type of food item prepared from flour fortified with iron of any variety of wheat DATA COLLECTION AND ANALYSIS: Two review authors independently screened the search results and assessed the eligibility of studies for inclusion, extracted data from included studies and assessed risks of bias. We followed Cochrane methods in this review.

MAIN RESULTS

Our search identified 3538 records, after removing duplicates. We included 10 trials, involving 3319 participants, carried out in Bangladesh, Brazil, India, Kuwait, Philippines, South Africa and Sri Lanka. We identified two ongoing studies and one study is awaiting classification. The duration of interventions varied from 3 to 24 months. One study was carried out among adult women and one trial among both children and nonpregnant women. Most of the included trials were assessed as low or unclear risk of bias for key elements of selection, performance or reporting bias. Three trials used 41 mg to 60 mg iron/kg flour, three trials used less than 40 mg iron/kg and three trials used more than 60 mg iron/kg flour. One trial used various iron levels based on type of iron used: 80 mg/kg for electrolytic and reduced iron and 40 mg/kg for ferrous fumarate. All included studies contributed data for the meta-analyses. Iron-fortified wheat flour with or without other micronutrients added versus wheat flour (no added iron) with the same other micronutrients added Iron-fortified wheat flour with or without other micronutrients added versus wheat flour (no added iron) with the same other micronutrients added may reduce by 27% the risk of anaemia in populations (risk ratio (RR) 0.73, 95% confidence interval (CI) 0.55 to 0.97; 5 studies, 2315 participants; low-certainty evidence). It is uncertain whether iron-fortified wheat flour with or without other micronutrients reduces iron deficiency (RR 0.46, 95% CI 0.20 to 1.04; 3 studies, 748 participants; very low-certainty evidence) or increases haemoglobin concentrations (in g/L) (mean difference MD 2.75, 95% CI 0.71 to 4.80; 8 studies, 2831 participants; very low-certainty evidence). No trials reported data on adverse effects in children (including constipation, nausea, vomiting, heartburn or diarrhoea), except for risk of infection or inflammation at the individual level. The intervention probably makes little or no difference to the risk of Infection or inflammation at individual level as measured by C-reactive protein (CRP) (mean difference (MD) 0.04, 95% CI -0.02 to 0.11; 2 studies, 558 participants; moderate-certainty evidence). Iron-fortified wheat flour with other micronutrients added versus unfortified wheat flour (nil micronutrients added) It is unclear whether wheat flour fortified with iron, in combination with other micronutrients decreases anaemia (RR 0.77, 95% CI 0.41 to 1.46; 2 studies, 317 participants; very low-certainty evidence). The intervention probably reduces the risk of iron deficiency (RR 0.73, 95% CI 0.54 to 0.99; 3 studies, 382 participants; moderate-certainty evidence) and it is unclear whether it increases average haemoglobin concentrations (MD 2.53, 95% CI -0.39 to 5.45; 4 studies, 532 participants; very low-certainty evidence). No trials reported data on adverse effects in children. Nine out of 10 trials reported sources of funding, with most having multiple sources. Funding source does not appear to have distorted the results in any of the assessed trials.

AUTHORS' CONCLUSIONS

Fortification of wheat flour with iron (in comparison to unfortified flour, or where both groups received the same other micronutrients) may reduce anaemia in the general population above two years of age, but its effects on other outcomes are uncertain. Iron-fortified wheat flour in combination with other micronutrients, in comparison with unfortified flour, probably reduces iron deficiency, but its effects on other outcomes are uncertain. None of the included trials reported data on adverse side effects except for risk of infection or inflammation at the individual level. The effects of this intervention on other health outcomes are unclear. Future studies at low risk of bias should aim to measure all important outcomes, and to further investigate which variants of fortification, including the role of other micronutrients as well as types of iron fortification, are more effective, and for whom.

The Impact of Nutrition-Specific and Nutrition-Sensitive Interventions on Hemoglobin Concentrations and Anemia: A Meta-review of Systematic Reviews

Anemia is a multifactorial condition arising from inadequate nutrition, infection, chronic disease, and genetic-related etiologies. Our aim was to assess the impact of nutrition-sensitive and nutrition-specific interventions on hemoglobin (Hb) concentrations and anemia to inform the prioritization and scale-up of interventions to address the multiple causes of anemia. We performed a meta-review synthesis of information by searching multiple databases for reviews published between 1990 and 2017 and used standard methods for conducting a meta-review of reviews, including double independent screening, extraction, and quality assessment. Quantitative pooling and narrative syntheses were used to summarize information. Hb concentration and anemia outcomes were pooled in specific population groups (children aged <5 y, school-age children, and pregnant women). Methodological quality of the systematic reviews was assessed using Assessing the Methodological Quality of Systematic Reviews (AMSTAR) criteria. Of the 15,444 records screened, we identified 118 systematic reviews that met inclusion criteria. Reviews focused on nutrition-specific interventions (96%). Daily and intermittent iron supplementation, micronutrient powders, malaria treatment, use of insecticide-treated nets (ITNs), and delayed cord clamping were associated with increased Hb concentration in children aged <5 y. Among children older than 5 y, daily and intermittent iron supplementation and deworming, and in pregnant women, daily iron-folic acid supplementation, use of ITNs, and delayed cord clamping, were associated with increased Hb concentration. Similar results were obtained for the reduced risk of anemia outcome. This meta-review suggests the importance of nutrition-specific interventions for anemia and highlights the lack of evidence to understand the influence of nutrition-sensitive and multifaceted interventions on the condition.

Wheat flour fortification with iron for reducing anaemia and improving iron status in populations

BACKGROUND

Anaemia is a condition where the number of red blood cells (and consequently their oxygen-carrying capacity) is insufficient to meet the body's physiologic needs. Fortification of wheat flour is deemed a useful strategy to reduce anaemia in populations.

OBJECTIVES

To determine the benefits and harms of wheat flour fortification with iron alone or with other vitamins and minerals on anaemia, iron status and health-related outcomes in populations over two years of age.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, CINAHL, and other databases up to 4 September 2019.

SELECTION CRITERIA

We included cluster- or individually randomised controlled trials (RCT) carried out among the general population from any country aged two years and above. The interventions were fortification of wheat flour with iron alone or in combination with other micronutrients. Trials comparing any type of food item prepared from flour fortified with iron of any variety of wheat were included.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened the search results and assessed the eligibility of studies for inclusion, extracted data from included studies and assessed risk of bias. We followed Cochrane methods in this review.

MAIN RESULTS

Our search identified 3048 records, after removing duplicates. We included nine trials, involving 3166 participants, carried out in Bangladesh, Brazil, India, Kuwait, Phillipines, Sri Lanka and South Africa. The duration of interventions varied from 3 to 24 months. One study was carried out among adult women and one trial among both children and nonpregnant women. Most of the included trials were assessed as low or unclear risk of bias for key elements of selection, performance or reporting bias. Three trials used 41 mg to 60 mg iron/kg flour, two trials used less than 40 mg iron/kg and three trials used more than 60 mg iron/kg flour. One trial employed various iron levels based on type of iron used: 80 mg/kg for electrolytic and reduced iron and 40 mg/kg for ferrous fumarate. All included studies contributed data for the meta-analyses. Seven studies compared wheat flour fortified with iron alone versus unfortified wheat flour, three studies compared wheat flour fortified with iron in combination with other micronutrients versus unfortified wheat flour and two studies compared wheat flour fortified with iron in combination with other micronutrients versus fortified wheat flour with the same micronutrients (but not iron). No studies included a 'no intervention' comparison arm. None of the included trials reported any other adverse side effects (including constipation, nausea, vomiting, heartburn or diarrhoea). Wheat flour fortified with iron alone versus unfortified wheat flour (no micronutrients added) Wheat flour fortification with iron alone may have little or no effect on anaemia (risk ratio (RR) 0.81, 95% confidence interval (CI) 0.61 to 1.07; 5 studies; 2200 participants; low-certainty evidence). It probably makes little or no difference on iron deficiency (RR 0.43, 95% CI 0.17 to 1.07; 3 studies; 633 participants; moderate-certainty evidence) and we are uncertain about whether wheat flour fortified with iron increases haemoglobin concentrations by an average 3.30 (g/L) (95% CI 0.86 to 5.74; 7 studies; 2355 participants; very low-certainty evidence). No trials reported data on adverse effects in children, except for risk of infection or inflammation at the individual level. The intervention probably makes little or no difference to risk of Infection or inflammation at individual level as measured by C-reactive protein (CRP) (moderate-certainty evidence). Wheat flour fortified with iron in combination with other micronutrients versus unfortified wheat flour (no micronutrients added) Wheat flour fortified with iron, in combination with other micronutrients, may or may not decrease anaemia (RR 0.95, 95% CI 0.69 to 1.31; 2 studies; 322 participants; low-certainty evidence). It makes little or no difference to average risk of iron deficiency (RR 0.74, 95% CI 0.54 to 1.00; 3 studies; 387 participants; moderate-certainty evidence) and may or may not increase average haemoglobin concentrations (mean difference (MD) 3.29, 95% CI -0.78 to 7.36; 3 studies; 384 participants; low-certainty evidence). No trials reported data on adverse effects in children. Wheat flour fortified with iron in combination with other micronutrients versus fortified wheat flour with same micronutrients (but not iron) Given the very low certainty of the evidence, the review authors are uncertain about the effects of wheat flour fortified with iron in combination with other micronutrients versus fortified wheat flour with same micronutrients (but not iron) in reducing anaemia (RR 0.24, 95% CI 0.08 to 0.71; 1 study; 127 participants; very low-certainty evidence) and in reducing iron deficiency (RR 0.42, 95% CI 0.18 to 0.97; 1 study; 127 participants; very low-certainty evidence). The intervention may make little or no difference to the average haemoglobin concentration (MD 0.81, 95% CI -1.28 to 2.89; 2 studies; 488 participants; low-certainty evidence). No trials reported data on the adverse effects in children. Eight out of nine trials reported source of funding with most having multiple sources. Funding source does not appear to have distorted the results in any of the assessed trials.

AUTHORS' CONCLUSIONS

Eating food items containing wheat flour fortified with iron alone may have little or no effect on anaemia and probably makes little or no difference in iron deficiency. We are uncertain on whether the intervention with wheat flour fortified with iron increases haemoglobin concentrations improve blood haemoglobin concentrations. Consuming food items prepared from wheat flour fortified with iron, in combination with other micronutrients, has little or no effect on anaemia, makes little or no difference to iron deficiency and may or may not improve haemoglobin concentrations. In comparison to fortified flour with micronutrients but no iron, wheat flour fortified with iron with other micronutrients, the effects on anaemia and iron deficiency are uncertain as certainty of the evidence has been assessed as very low. The intervention may make little or no difference to the average haemoglobin concentrations in the population. None of the included trials reported any other adverse side effects. The effects of this intervention on other health outcomes are unclear.

Fortification of maize flour with iron for controlling anaemia and iron deficiency in populations

BACKGROUND

Approximately 800 million women and children have anaemia, a condition thought to cause almost 9% of the global burden of years lived with disability. Around half this burden could be amenable to interventions that involve the provision of iron. Maize (corn) is one of the world's most important cereal grains and is cultivated across most of the globe. Several programmes around the world have fortified maize flour and other maize-derived foodstuffs with iron and other vitamins and minerals to combat anaemia and iron deficiency.

OBJECTIVES

To assess the effects of iron fortification of maize flour, corn meal and fortified maize flour products for anaemia and iron status in the general population.

SEARCH METHODS

We searched the following international and regional sources in December 2017 and January 2018: Cochrane Central Register of Controlled Trials (CENTRAL); MEDLINE; MEDLINE (R) In Process; Embase; Web of Science (both the Social Science Citation Index and the Science Citation Index); CINAHL Ebsco; POPLINE; AGRICOLA (agricola.nal.usda.gov); BIOSIS (ISI); Bibliomap and TRoPHI; IBECS; Scielo; Global Index Medicus - AFRO (includes African Index Medicus); EMRO (includes Index Medicus for the Eastern Mediterranean Region); LILACS; PAHO (Pan American Health Library); WHOLIS (WHO Library); WPRO (includes Western Pacific Region Index Medicus); IMSEAR, Index Medicus for the South-East Asian Region; IndMED, Indian medical journals; and the Native Health Research Database. We searched clinicaltrials.gov and the International Clinical Trials Registry Platform (ICTRP) for any ongoing or planned studies on 17 January 2018 and contacted authors of such studies to obtain further information or eligible data if available.For assistance in identifying ongoing or unpublished studies, we also contacted relevant international organisations and agencies working in food fortification on 9 August 2016.

SELECTION CRITERIA

We included cluster- or individually randomised controlled trials and observational studies. Interventions included (central/industrial) fortification of maize flour or corn meal with iron alone or with other vitamins and minerals and provided to individuals over 2 years of age (including pregnant and lactating women) from any country.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed the eligibility of studies for inclusion, extracted data from included studies and assessed the risk of bias of the included studies. Trial designs with a comparison group were included to assess the effects of interventions. Trial designs without a control or comparison group (uncontrolled before-and-after studies) were included for completeness but were not considered in assessments of the overall effectiveness of interventions or used to draw conclusions regarding the effects of interventions in the review.

MAIN RESULTS

Our search yielded 4529 records. After initial screening of titles and abstracts, we reviewed the full text of 75 studies (80 records). We included 5 studies and excluded 70. All the included studies assessed the effects of providing maize products fortified with iron plus other vitamins and minerals versus unfortified maize flour. No studies compared this intervention to no intervention or looked at the relative effect of flour and products fortified with iron alone (without other vitamins and minerals). Three were randomised trials involving 2610 participants, and two were uncontrolled before-and-after studies involving 849 participants.Only three studies contributed data for the meta-analysis and included children aged 2 to 11.9 years and women. Compared to unfortified maize flour, it is uncertain whether fortifying maize flour or corn meal with iron and other vitamins and minerals has any effect on anaemia (risk ratio (RR) 0.90, 95% confidence interval (CI) 0.58 to 1.40; 2 studies; 1027 participants; very low-certainty evidence), or on the risk of iron deficiency (RR 0.75, 95% CI 0.49 to 1.15; 2 studies; 1102 participants; very low-certainty evidence), haemoglobin concentration (mean difference (MD) 1.25 g/L, 95% CI -2.36 to 4.86 g/L; 3 studies; 1144 participants; very low-certainty evidence) or ferritin concentrations (MD 0.48 µg/L, 95% CI -0.37 to 1.33 µg/L; 1 study; 584 participants; very low-certainty evidence).None of the studies reported on any adverse effects. We judged the certainty of the evidence to be very low based on GRADE, so we are uncertain whether the results reflect the true effect of the intervention. We downgraded evidence due to high risk of selection bias and unclear risk of performance bias in one of two included studies, high heterogeneity and wide CIs crossing the line of no effect for anaemia prevalence and haemoglobin concentration.

AUTHORS' CONCLUSIONS

It is uncertain whether fortifying maize flour with iron and other vitamins and minerals reduces the risk of anaemia or iron deficiency in children aged over 2 years or in adults. Moreover, the evidence is too uncertain to conclude whether iron-fortified maize flour, corn meal or fortified maize flour products have any effect on reducing the risk of anaemia or on improving haemoglobin concentration in the population.We are uncertain whether fortification of maize flour with iron reduces anaemia among the general population, as the certainty of the evidence is very low. No studies reported on any adverse effects.Public organisations funded three of the five included studies, while the private sector gave grants to universities to perform the other two. The presence of industry funding for some of these trials did not appear to positively influence results from these studies.The reduced number of studies, including only two age groups (children and women of reproductive age), as well as the limited number of comparisons (only one out of the four planned) constitute the main limitations of this review.

Considerations on the food fortification policy in Brazil

Government health authorities approved, in December 2002, the ANVISA (National Sanitary Vigilance Agency) resolution number 344, making the addition of iron and folic acid to all wheat and maize flours industrialized in Brazil obligatory. After a brief review of iron deficiency, iron overload and folic acid deficiency several questions and remarks need to be made about this universal food fortification program. Iron salts and folic acid are drugs widely used in medicine and they may present undesirable side effects. There are potential risks with offering iron to the normal population for a long period of time and to patients with iron overload. Other important remarks are: there is no medical follow up of this treatment in the Brazilian population; patients can decide the quantity of foods (and of these nutrients) that they want to ingest; fortified foods may correct iron deficiency anemia but not necessarily the causes, which include gastrointestinal neoplasms; and folic acid in the diet may interfere with several treatment protocols that use folic acid antagonists, such as methotrexate. Finally, with the exception of some social programs, the costs of treatment using fortified foods are passed on to the population. Considering that Brazil has 330,000 active medical doctors it is suggested that our Health Ministry should invite them to take care of these important medical conditions.

Fatores associados à ocorrência de anemia em crianças menores de seis anos: uma revisão sistemática dos estudos populacionais

OBJETIVOS: revisar os artigos publicados de 1997 a 2010, com amostras populacionais representativas para crianças menores de seis anos, que estimaram a prevalência da anemia e/ou deficiência de ferro e seus fatores associados, por meio da análise laboratorial de hemoglobina ou ferritina. MÉTODOS: os artigos foram revisados sistematicamente, utilizando as palavras-chaves: anemia, iron-deficiency; anemia, iron-deficiency/epidemiology; anemia, iron-deficiency/etiology; child, preschool e risk factors nas bases de dados PubMed, SciELO e LILACS. RESULTADOS: os fatores mais citados foram: idade da criança, escolaridade materna, renda familiar, diarréia, área geográfica, índice de riqueza do domicílio, peso ao nascer, indicador altura/idade, indicador peso/altura, etnia, sexo, densidade de ferro e calorias provenientes do leite de vaca. A idade da criança foi comum nos estudos nacionais e internacionais. A escolaridade materna e fatores socio-econômicos e ambientais mostraram associação com a anemia nos estudos realizados nas regiões em desenvolvimento. O sobrepeso e a exposição passiva ao fumo surgem como variáveis pouco investigadas. CONCLUSÕES: a análise demonstra a multiplicidade de fatores associados à anemia/deficiência de ferro existentes em diferentes contextos.

Prevalence of Anemia in Children Three to 12 Months Old in a Health Service in Ribeirão Preto, SP, Brazil

Iron deficiency anemia is the most common nutritional deficiency among children. This cross-sectional, descriptive and quantitative study is part of a multicenter project, which verified the prevalence of anemia in children aged three to 12 months, treated by a health service unit in Ribeirão Preto, SP, Brazil. Interviews with mothers and determining hemoglobin dosage were carried out with 121 children who participated in the study. Two international criteria were adopted as parameters of anemia according to the children's age. Descriptive statistics, measures of central tendency and associations were used for data analysis. The prevalence of anemia among 69 children aged three to 5 months was 20.2% and 48.0% among 52 children aged six to 12 months. The total prevalence of anemia was 32.2%. There was significant association between anemia and children's age, and anemia and the consumption of liquid cow's milk.

Estimativa da ingestão de ferro e vitamina C em adolescentes no ciclo menstrual

Avaliou-se o nível de ingestão de ferro e vitamina C, em adolescente nas três fases do ciclo menstrual. O consumo alimentar de trinta adolescentes foi analisado pela técnica de registro, durante as fases pré-menstrual, menstrual e pós-menstrual, com a análise de dois registros por indivíduo, em cada fase. A prevalência da ingestão foi feita considerando seis registros alimentares de cada adolescente. Os padrões utilizados como referência foram as Dietary Reference Intakes (DRI)- Estimated Average Requirement (EAR) do Institute of Medicine (IOM), utilizando as abordagens probabilística e ponto de corte, para o ferro e vitamina C, respectivamente, além dos valores do Recommended Dietary Allowances (National Research Council). As adolescentes tinham 15,5 ± 1,7 anos, com idade da menarca de 11,8 ± 1,1 anos e ginecológica de 3,6 ± 1,9 anos. O consumo mediano de ferro foi 10,6 mg/dia e de vitamina C, 77,6 mg/dia. Observou-se pelas DRI-EAR uma prevalência de inadequação para ferro de 22,6% e de vitamina C 34% e pelo National Research Council, de 63,3% e 20%, respectivamente. Apesar da divergência entre os padrões, os resultados apontam risco nutricional para a população estudada. Sugere-se a realização de mais estudos dietéticos, utilizando as DRI-EAR, favorecendo diagnósticos nutricionais com subsequente medidas de intervenção.

Efeito da fortificação semanal do arroz com ferro quelato sobre a freqüência de anemia e concentração de hemoglobina em crianças de creches municipais do Rio de Janeiro, Brasil

Trata-se de um ensaio clínico comunitário, duplo-cego, controlado por placebo. Durante 16 semanas, as crianças do grupo intervenção (GI, n = 180) receberam arroz fortificado com ferro, e as do grupo controle (GC, n = 174) receberam arroz com placebo. Considerou-se presença de anemia quando hemoglobina < 11,0g/dL. A comparação da variação média na hemoglobina intergrupos, ajustada por idade e uso de outros suplementos de ferro, foi feita pelo teste t de Student. A concentração de hemoglobina aumentou em ambos os grupos, com incremento médio de 0,42g/dL no GI (11,28±1,23g/dL para 11,75±1,16g/dL; p < 0,001) e de 0,49g/dL no GC (11,06±1,13g/dL para 11,51±1,16g/dL; p < 0,001). A freqüência de anemia reduziu (p < 0,01) em ambos os grupos (37,8% para 23,3% em GI e 45,4% para 33,3% em GC), sem diferença entre os mesmos. As crianças que receberam quantidade total de ferro > 53,76mg pelo arroz fortificado tiveram maior aumento na hemoglobina do que aquelas que receberam quantidades inferiores (0,94g/dL vs. 0,39g/dL; p = 0,03). Sugere-se que esse tipo de intervenção pode ser útil no controle da anemia quando o consumo do alimento fortificado é adequado.

Prevalência de anemia em gestantes e a fortificação de farinhas com ferro

Avaliou-se o impacto da fortificação das farinhas com ferro, na prevalência de anemia e concentração de hemoglobina de gestantes. Este estudo transversal retrospectivo foi desenvolvido em um Centro de Saúde Escola do município de São Paulo - SP. Os dados, colhidos de setembro a dezembro de 2006, foram obtidos de 750 prontuários de gestantes distribuídas em dois grupos (não fortificado e fortificado), antes e após a fortificação. Gestantes com nível de hemoglobina inferior a 11g/dl foram consideradas anêmicas. Realizou-se análise de regressão linear múltipla. A anemia afetava 9,2% e 8,6% das gestantes, antes e após a implantação do programa, respectivamente (p>0,05). A análise múltipla não evidenciou diferença estatística na média de hemoglobina entre os grupos (p=0,117). Os resultados indicaram uma baixa prevalência de anemia e médias de hemoglobina similares entre os grupos, fato que provavelmente não permitiu constatar o efeito da fortificação das farinhas.