A beneficial effect of periodic vitamin A supplementation on childhood mortality has been demonstrated, but the effect on morbidity is less clear. We investigated the effect of vitamin A supplementation on diarrhoea and acute lower-respiratory-tract infections (ALRI) in children from northeastern Brazil in a randomised, double-blind, placebo-controlled community trial. 1240 children aged 6-48 months were assigned vitamin A or placebo every 4 months for 1 year. They were followed up at home three times a week, and data about the occurrence and severity of diarrhoea and ALRI were collected. Any child with cough and respiratory rate above 40 breaths per min was visited by a paediatrician. The overall incidence of diarrhoea episodes was significantly lower in the vitamin-A-supplemented group than in the placebo group (18.42 vs 19.58 x 10(-3) child-days; rate ratio 0.94 [95% Cl 0.90-0.98]). The benefit of supplementation was greater as regards severe episodes of diarrhoea; the incidence was 20% lower in the vitamin A group than in the placebo group (rate ratio 0.80 [0.65-0.98]). With the standard definition of diarrhoea (> or = 3 liquid or semi-liquid stools in 24 h) the effect of vitamin A on mean daily prevalence did not reach significance, but as the definition of diarrhoea was made more stringent (increasing number of stools per day), a significant benefit became apparent, reaching for diarrhoea with 6 or more liquid or semi-liquid stools in 24 h a 23% lower prevalence. We found no effect of vitamin A supplementation on the incidence of ALRI. The reduction in severity of diarrhoea may be the most important factor in the lowering of mortality by vitamin A supplementation.

Results of the study reinforce the concept of diarrhea burden as a major determinant of poor growth in children under 5 y of age. Actions targeted to decrease the risk factors for the occurrence of diarrhea may represent an important component of interventions aimed to ensure satisfactory child growth.

O objetivo deste estudo foi avaliar o efeito da duração da amamentação exclusiva e mista sobre os níveis de hemoglobina de lactentes. Trata-se de um estudo de seguimento com seis meses de duração, envolvendo 150 crianças nascidas na maternidade de Mutuípe, Bahia, Brasil. Mensalmente, as crianças eram submetidas ao exame de sangue para avaliação dos níveis de hemoglobina e realizava-se coleta de dados de consumo alimentar. Foram obtidos, ainda, dados obstétricos e sócio-econômicos. Utilizou-se o modelo linear de efeitos mistos para investigar as associações de interesse. Ao final do seguimento, a perda amostral foi de 15,3%, e detectou-se uma prevalência de 71,7% de anemia. Constatou-se um incremento de 0,091g/dL nos níveis de hemoglobina a cada mês de duração de aleitamento materno exclusivo (p = 0,031), enquanto, a cada mês de duração de aleitamento materno misto, os níveis de hemoglobina declinaram em 0,097g/dL (p = 0,017). Concluiu-se que as práticas alimentares inadequadas parecem estar diretamente envolvidas na etiologia da deficiência nutricional de ferro nesse período da vida.