In developing countries such as Bangladesh, micronutrient deficiency, especially among children, presents a concerning health issue to both domestic and international health officials. In particular, many children lack sufficient supplies of iron and zinc in their diets.
Iron is known to have significant effects in decreasing anemia and psychomotor activity, while zinc helps to both reduce child morbidity and mortality from diarrhea and pneumonia and to improve growth.
In an effort to efficiently deliver both of these supplements to the greatest number of children, health specialists and nutritionists have frequently distributed these two supplements together; however, these attempts have sometimes resulted in negative outcomes because of detrimental interactions between the two nutrients.
Recently, a group of researchers at the Hopkins Medical Institutions, in collaboration with the Hopkins Bloomberg School of Public Health and the International Center for Diarrhoeal Disease Research in Bangladesh, have carried out a study in a rural Bangladeshi population to further study the effectiveness of various iron and zinc supplement delivery methods to improve diarrhea and anemia among the children of the population.
"I was interested in the topic because, in international health, there is often a lot of attention given to HIV/AIDS, which is definitely a serious issue, but I think we sometimes forget about the chronic issues of malnutrition which are harder to quantify and thus may get less time in the limelight," Stephanie Chang, a physician at the Agency for Healthcare Research and Quality and a lead investigator in this study, said.
A randomized group of approximately 1,000 children aged six to 18 months were studied over a period of six months. They were each given one of five different intervention regimens containing a placebo, only iron, only zinc, iron and zinc combined or iron and zinc separately.
The data were collected by trained village health workers, or VHWs, who were supervised by four trained individuals with earlier research experience and at least 12 years of school. Survey methods and blood samples were drawn from the participants periodically throughout the study period.
As shown by this study, whether administered separately or together, these supplements are crucial in order for a child to maintain a healthy diet. The main results of this study had to do with the relationship between iron and zinc supplements and diarrhea.
Zinc alone did not show any strong correlation with diarrhea incidence, prevalence, or duration, but iron alone increased diarrhea prevalence. Combined zinc and iron reduced diarrhea, including bloody diarrhea, incidence and prevalence when compared to iron alone.
In other words, iron alone was found to increase diarrhea, but these harmful effects were alleviated by adding zinc, either separately or combined. Other outcomes that were noted, particularly anemia, also showed improvement from only iron alone and also with a combination of iron and zinc.
Because of the benefits and risks of iron and zinc supplementation, policy makers in developing countries have encountered increased difficulty in assigning the most cost-effective and safest regimens for their constituent populations.
For example, vomiting, a further cause of dehydration in addition to diarrhea, is a widely observed side effect of combined delivery of iron and zinc tablets.
Also, the correlation between diarrhea and iron and zinc supplementation, as in other studies, suffers from the possible influence of other confounding factors such as improved nutrition and health over time due to other causes, such as better food, shelter, sanitation or other living conditions.
"We need to look at both the benefits and harms of giving any intervention and to consider the context that the intervention will actually be used in order for research to be helpful," Chang said.
"It's important to consider how much these findings apply to other populations. Our study was conducted in a non-malarial population, non-HIV population, but with some baseline degree of malnutrition. When looking more closely at the data, there is some suggestion that a combined supplement may not work as well in stunted children (short for age) and this is an area for future research."
