This blog is cross posted from the IFPRI website and was originally written by Vivian Hoffmann, Jef Leroy, and Kelly Jones. The post is based on their recent article: “The impact of reducing dietary aflatoxin exposure on child linear growth: a cluster randomized control trial in eastern Kenya,” which appeared in BMJ Global Health.
Aflatoxins are invisible, odorless, and tasteless poisons, produced by a mold commonly infecting crops such as maize and groundnuts, both in the field and in storage. Aflatoxins take an enormous toll on health and economies across Africa and beyond. Aflatoxins also impact international trade as crops tested above regulatory limits cannot be exported.
But what about child stunting? Aflatoxin exposure through diet is often cited as a cause of this very serious problem. To address child stunting it is necessary to understand its causes to ensure effective interventions. Current evidence on the aflatoxin-stunting link is limited to observational research. A confounding factor that is difficult to rule out in these studies is socioeconomic status. Children in poorer households are often fed diets deficient in micro- or macronutrients and suffer from more frequent infections, both of which contribute to growth retardation. Poverty is also associated with aflatoxin exposure, so if not adequately controlled for, the association between aflatoxin and stunting will be overestimated.
To overcome this limitation of observational studies, the research team undertook the first randomized controlled trial examining how reducing aflatoxin contamination in the food consumed by children might affect their linear growth. This approach allowed to better isolate the extent to which the observed relationship between aflatoxin exposure and stunting is causal. This knowledge will enable stakeholders and policymakers to identify and implement more effective interventions.
The study, Mitigating Aflatoxin Exposure to Improve Child Growth in Eastern Kenya (MAICE), was conducted between 2013 to 2016 in 56 villages in rural parts of Kenya, where maize is the predominant crop and aflatoxicosis and aflatoxin contamination have frequently been reported. Study communities were randomly assigned to the treatment or the comparison arm. In the treatment communities, maize in study households was regularly tested for aflatoxin and swapped for clean maize if found to be contaminated. Families in these villages were also able to purchase “clean,” aflatoxin-free maize provided to local markets. The study also followed pregnant women and their children up to 24 months of age.
The results of the study find a complex relationship between aflatoxin and child linear growth. At the end of the study, children in communities with the intervention had serum aflatoxin levels 27 percent lower than those in control communities. However, while their stunting levels were significantly lower than those in control communities halfway through the study, that impact was not sustained: Stunting rates climbed back to the levels found in the control group during the second half of the study.
These results prompt many questions that require further exploration: (1) Are there certain ages or growth periods during which avoiding exposure to aflatoxin is more critical for ensuring proper growth? (2) Are larger reductions in aflatoxin exposure necessary to sustain progress? (3) How do aflatoxin impacts weigh in comparison to other stunting causes, including nutrient intake? (4) Does lowering aflatoxin levels at early age provide lasting benefits to children even if other factors conspire to result in stunting later? and (5) How do seasonal, geographical, and temporal factors impact aflatoxin impacts?
While the dynamics are complicated and these questions all warrant further exploration, one thing is clear: Aflatoxin’s negative effects on human health and trade are real and urgently need to be addressed.
Vivian Hoffmann is a Research Fellow with IFPRI's Markets, Trade, and Institutions Division (MTID); Jef Leroy is Senior Research Fellows with IFPRI's Poverty, Health, and Nutrition Division (PHND); Kelly Jones is an Assistant Professor in the Economics Department at American University. Janet Hodur, A4NH Communications Specialist, assisted with writing the original piece, which also appears on the A4NH blog.
