Does aflatoxin exposure cause child stunting? PROJECT SPOTLIGHT: Mitigating Aflatoxin Consumption for Improving Child Growth in Eastern Kenya (MAICE), May 19, 2015 by IFPRI.
Excerpts: Childhood stunting is associated with delays in cognitive development, lower school achievement, and lower earnings in adulthood. In 2009, researchers estimated a 42 percent prevalence of child stunting in the Eastern Province of Kenya—20 percent higher than the Kenyan average. This is despite the fact that this region had less poverty and lower prevalence of childhood illness than five of the other seven provinces in the country. This suggests factors beyond poverty and illness may be affecting child growth here. We are implementing a study to determine if aflatoxin exposure, which is notoriously high in Eastern Kenya, could be the culprit.
A growing body of research is highlighting an association between aflatoxin exposure and child linear growth. The hypothesized direct pathway is a biological one: aflatoxin consumption may increase infection by suppressing the immune system or reduce nutrient absorption by changing metabolism. However, given the lack of intervention studies, it is not clear what role is played by aflatoxin, versus other factors such as household socioeconomic status, child illness, and dietary intake.
The Mitigating Aflatoxin Consumption for Improving Child Growth in Eastern Kenya (MAICE) study aims to establish if a causal relationship between aflatoxin exposure and linear child growth exists. In this controlled study we reduce dietary aflatoxin while holding constant other factors that affect child growth.
The study focuses on children in the last trimester of their mothers’ pregnancy to age two, as this is the primary period of stunting. Throughout 2013 and 2014, the MAICE study enrolled 1829 pregnant women across 56 villages in Meru and Tharaka-Nithi Counties. Half these villages were randomly assigned to treatment. Based on our data analysis indicating that nearly all this population’s exposure to aflatoxin occurs through tainted maize, we reduced dietary aflatoxin in the treatment villages by testing and replacing contaminated maize from home stores, and providing certified aflatoxin-safe maize for purchase in a local shop.
Baseline data collection, which included tests for aflatoxin albumin in the blood serum of pregnant mothers, found aflatoxin in the blood of all of tested participants. The levels of exposure were comparable with those observed in other populations for which a strong association between aflatoxin exposure and impaired child growth has been shown.
To determine if aflatoxin impacts child growth, we calcuated that we would need to reduce dietary exposure in the treatment group by at least 37 percent. Our preliminary calculations show that we more than met that target, reducing exposure by more than 50 percent.
Based on previous studies, we calculated that dietary aflatoxin exposure in the treatment group would need to be reduced by at least 35 percent for an impact on child growth to be detectable. This means exposure through maize would need to be reduced by at least 37 percent. Preliminary calculations of impact show that our intervention is achieving a reduction in aflatoxin exposure of 50 percent for the treatment group.
Achieving such a reduction in exposure carries significant costs. The intervention involved visiting all 1800-plus households every month to perform on-site rapid tests of any stored maize that the household intends to consume in the next two months. Harvested crops testing above the regulatory limit of 10 parts per billion were removed and replaced with aflatoxin-safe maize. Further, because many enrolled households purchase a large share of their consumed maize, since February of 2014 we have stocked a local maize purveyor in each of the 28 treatment villages with certified aflatoxin-safe maize grain and flour for enrolled households to purchase at a price equivalent to the least expensive maize they currently sell.
While this intensive intervention is not replicable at scale, it will provide the first experimental evidence of the impact of aflatoxin exposure on child growth.
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