Globally, more than two billion people are estimated to be deficient in key vitamins and minerals, particularly iodine, iron and zinc. The majority of these people live in low-income settings and are typically deficient in more than one micronutrient. However, micronutrient deficiency among breastfeeding mothers and their infants also remains an issue in high-income settings, specifically among women who avoid meat and/or milk, women who may lack sufficient supplies of vitamin B12 and vitamin D, and/or women who are iron-deficient. Young children, pregnant and lactating women are particularly vulnerable to micronutrient deficiencies. They not only have a relatively greater need for vitamins and minerals because of their physiological state, but are also more susceptible to the harmful consequences of deficiencies. Multiple-micronutrient supplementation might be an option to solve these problems.
The objective of this review was to evaluate the effects of multiple-micronutrient supplementation in breastfeeding mothers on maternal and infant outcomes.
We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (30 September 2015) and reference lists of retrieved studies.
Randomised controlled trials of multiple-micronutrient supplementation of three or more micronutrients versus placebo, no supplementation or supplementation with two or fewer micronutrients, irrespective of dosage of micronutrients, in breastfeeding mothers.
Two review authors independently assessed trials for inclusion and risk of bias, extracted data and checked them for accuracy.
We found no studies that compared multiple-micronutrient supplementation (with three or more micronutrients) versus supplementation with two or fewer micronutrients.Two small studies (involving a total of 52 women) were included. One study compared multiple micronutrients with placebo and the other study compared multiple micronutrients with a group who received no supplementation. The studies were carried out in Brazil (36 adolescent mothers) and the USA (16 women) and included women with a low socioeconomic status. A lack of information in the study reports meant that risk of bias could not be adequately assessed (unclear risk of bias for many domains). There were no quantitative data for any of this review's outcomes so meta-analysis was not possible.Neither of the studies reported on the primary outcomes of interest in this review: maternal morbidity (febrile illness, respiratory tract infection, diarrhoea), adverse effects of micronutrients within three days of receiving the supplement, infant mortality (defined as a child dying before completing the first year of age).One study reported qualitatively on maternal anaemia (a secondary outcome of this review) - the study found that multiple-micronutrient supplementation was effective for recuperating from anaemia but there were no data for inclusion in our analyses. Maternal satisfaction was not reported in the included studies. Similarly, none of this review's infant secondary outcomes were reported in the included studies: clinical micronutrient deficiency; morbidity episodes (febrile illness, respiratory tract infection, diarrhoea, other), adverse effects of micronutrients within three days of receiving the supplement.