Breast feeding and vitamin A deficiency among children attending a diarrhoea treatment centre in Bangladesh: a case-control study.

OBJECTIVE: To determine the effect of breast feeding on the risk of xerophthalmia in children aged 6 months to 3 years attending a diarrhoea treatment centre in Bangladesh.

DESIGN: Case-control study based on stratified analysis (Mantel-Haenszel) and multivariate analysis (logistic regression) of data from a treatment centre based surveillance system.

SETTING: A large diarrhoea treatment centre in Dhaka, Bangladesh.

PATIENTS: 2687 children aged 6 months to 3 years representing a 4% systematic sample of all children in this age group treated yearly at the centre over three consecutive years. 66 of the children were cases of xerophthalmia (that is, they had Bitot's spots or corneal lesions or night blindness or night blindness plus conjunctival xerosis or any combination of these) and the remaining 2621 did not have signs or symptoms of vitamin A deficiency. This second group served as controls.

MAIN OUTCOME MEASURE: Xerophthalmia and breast fed at onset of diarrhoea or presentation.

RESULTS: The odds ratio relating breast feeding to vitamin A deficiency after adjustment for a large number of confounding variables (0.26 (95% confidence interval 0.14 to 0.49); p less than 0.001) reflected a 74% reduction in the risk of vitamin A deficiency among breast fed children. The estimated reduction of risk did not decline with age, and some 49% of children aged 24-35 months were still being breast fed. The odds ratio relating breast feeding to xerophthalmia in the third year of life (0.35 (95% confidence interval 0.35 to 0.86) reflected a 65% reduced risk of vitamin A deficiency. Other important risk factors or prognostic indicators for xerophthalmia as identified by multivariate analysis were recent measles, prolonged diarrhoea, severe protein energy malnutrition, and poor socioeconomic state.

CONCLUSIONS: These results indicate that breast feeding was associated with a substantial reduction of the risk of vitamin A deficiency extending to the third year of life and support the recommendation that mothers in developing countries should be advised to breast feed for as long as possible.