Review question
Does providing agricultural and nutritional education about how to reduce the intake of aflatoxins (from contaminated food crops) in households and communities in low and middle-income countries (LMICs) improve the growth of infants and children compared to usual or no education?
Background
Aflatoxins are toxins produced by moulds that contaminate food crops. Maize and groundnuts are the major dietary sources of aflatoxins, as they are eaten in large amounts by many people living in LMICs. Some research from LMICs suggests that there may be a link between aflatoxin intake during pregnancy and early childhood, and growth in infants and young children.
Study Characteristics
We included three trials, conducted in pregnant and breastfeeding women (1168 mother-child pairs), women of childbearing age (N = 231), and infants and young children (< 59 months old), from rural, subsistence maize-farming communities in Kenya, Tanzania, and Zimbabwe. One trial in Tanzania, at unclear risk of bias overall, provided data for this review, since one trial did not report any outcomes relevant to this review, and we were unable to obtain unpublished growth data for another, even after contacting the study authors.
The trial, conducted in breastfeeding women and their babies, studied the effects of agricultural education (demonstrations to change farmers' practices after harvesting their maize crops to reduce aflatoxins (for example, by handsorting and de-hulling the maize, using drying sheets and insecticides) on the babies' weight, standardised for age (weight-for-age z-score (WAZ)), after six months (the z-score measures the difference between these babies and the median of a population of similar babies). Farmers in the control group received routine services from agriculture extension workers.
Key results
Very low-certainty evidence from one trial suggested that the WAZ of 128 children from farmers' households who received agricultural education may improve by a z-score of 0.57, compared to 121 children from households where farmers only received routine services. This means that a baby girl in the intervention group, with a healthy weight, would gain about 450 to 690 grams more weight between three to nine months, compared to a baby girl in the control group. This is a meaningful difference.
Another way of measuring the effect is to compare the proportion of underweight infants (WAZ ≥ 2 standard deviations below the reference median value) per group, after the intervention. In this case, agricultural education may reduce the proportion of underweight children, on average, by 6.7% (very low-certainty evidence), compared to routine services.
None of the included studies addressed the effects of nutritional education on length of height, or on unintended effects of agricultural or nutritional education.
Evidence about the effects on child growth of agricultural or nutritional education interventions that reduce aflatoxin exposure in LMICs was very limited. Data from one trial suggested that agricultural education, aimed at changing farmers' post-harvest practices to reduce aflatoxin exposure, may result in the babies' increased weight-for-age, compared to usual or no education.
The literature was searched to August 2019.
Quality of the evidence
We have very little confidence in the results. The true effect may be substantially different.
Evidence on the effects on child growth in LMICs of agricultural or nutritional education interventions that reduce aflatoxin exposure was very limited; no included study reported on linear growth. Very low-certainty evidence suggested that agricultural education aimed at changing farmers' post-harvest practices to reduce aflatoxin exposure by using demonstrations, may result in an increase in WAZ, when compared to usual or no education.
Aflatoxins are carcinogenic mycotoxins that contaminate many food crops. Maize and groundnuts are prone to aflatoxin contamination, and are the major sources of human exposure to aflatoxins, due to their high intake as staple foods, particularly in low- and middle-income countries (LMICs). Observational studies suggest an association between dietary exposure to aflatoxins during pregnancy and early childhood and linear growth in infants and young children.
To assess the effects on pre- and postnatal growth outcomes when agricultural and nutritional education interventions during the post-harvest period that aim to reduce aflatoxin exposure are compared to usual support or no intervention. We assessed this in infants, children, and pregnant and lactating women at the household or community level in LMICs.
In July and August 2019, we searched: CENTRAL, MEDLINE, Embase, CINAHL, Web of Science Core Collection, Africa-Wide, LILACS, CAB Abstracts, Agricola, and two trials registers. We also checked the bibliographies of the included studies and contacted relevant mycotoxin organisations and researchers for additional studies.
We included randomised controlled trials (RCTs) and cluster-RCTs of agricultural education and nutritional education interventions of any duration, at the household or community level, aimed at reducing aflatoxin intake by infants, children, and pregnant and lactating women, in LMICs during the post-harvest period, compared to no intervention or usual support. We excluded studies that followed participants for less than four weeks. We assessed prespecified prenatal (at birth) and postnatal growth outcomes (during infancy, childhood, and adolescence), with linear growth (as the primary outcome), infectious disease morbidity, and unintended consequences.
Two authors independently assessed study eligibility using prespecified criteria, extracted data, and assessed risk of bias of included RCTs. We evaluated the certainty of the evidence using GRADE, and presented the main results in a 'Summary of findings' table.
We included three recent cluster-RCTs reporting the effects of agricultural education plus post-harvest technologies, compared to usual agricultural support or no intervention. The participants were pregnant women and their children, lactating women and their infants (< 6 months), women of childbearing age, and young children (< 59 months), from rural, subsistence maize-farming communities in Kenya, Zimbabwe, and Tanzania.
Two trials randomised villages to the intervention and control groups, including a total of at least 979 mother-child pairs from 60 villages. The third trial randomised 420 households, including 189 mother-child pairs and 231 women of childbearing age. Duration of the intervention and follow-up ranged between five and nine months. Due to risk of attrition bias, the overall risk of bias was unclear in one trial, and high in the other two trials.
None of the included studies addressed the effects of nutritional education on pre- and postnatal growth.
One trial reported outcomes not prespecified in our review, and we were unable to obtain unpublished growth data from the second trial, even after contacting the authors. The third trial, in lactating women and their infants in Tanzania, reported on the infants' weight-for-age z-score (WAZ) after six months. This trial found that providing agricultural education aimed at changing farmers' post-harvest practices to reduce aflatoxin exposure, by using demonstrations (e.g. handsorting, de-hulling of maize, drying sheets, and insecticides), may improve WAZ in infants from these farmers' households, on average, by 0.57 (95% confidence interval (CI) 0.16 to 0.98; 1 study; 249 participants; very low-certainty evidence), compared to infants from households where the farmers received routine agricultural extension services.
Another way of reporting the effect on WAZ is to compare the proportion of underweight infants (WAZ > 2 SD below the reference median value) per group. This trial found that the intervention may reduce the proportion of underweight infants in the intervention households by 6.7% (95% CI -12.6 to -1.4; 249 participants; very low-certainty evidence) compared to control households.
No studies reported on unintended effects of agricultural and nutritional education.