Protocol for the trial to establish a causal linkage between mycotoxin exposure and child stunting: a cluster randomized trial

The effect of an intervention to reduce aflatoxin consumption from 6 to 18 mo of age on length-for-age z-scores in rural Tanzania: a cluster-randomized trial

BACKGROUND

Linear growth faltering continues to negatively affect children in low- and middle-income countries and is associated with poor cognitive, developmental, and educational outcomes. Laboratory and observational data suggest that aflatoxin (AF) is a contributor to stunting.

OBJECTIVE

The Mycotoxin Mitigation Trial was a cluster-randomized, community-based 2-group trial conducted in Kongwa District, Tanzania, between 2018 and 2020. The trial assessed whether a 12-mo intervention to reduce AF consumption increased length-for-age z-scores (LAZ) at 18 mo.

METHODS

Low-AF maize and groundnut flours were provided to the intervention group each month; skin lotion was distributed to the control group monthly. Infant and young child feeding education was delivered equally in 52 health facilities (clusters). Anthropometry and the AF blood biomarker serum AF-albumin (AF-alb) were assessed at 6, 12, and 18 mo of age. Outcomes were analyzed as intention-to-treat and per-protocol using linear mixed-effects models.

RESULTS

Two thousand eight hundred forty-two maternal-infant dyads were recruited into the study. The intervention did not create a contrast in AF-alb. At 18 mo, 36% (n = 186/520) of infants had detectable levels of AF-alb compared with 54% (n = 195/364) at baseline, with no difference between groups. Mean LAZ in the intervention group at 18 mo was -1.83 (n = 1231, 95% CI: -1.93, -1.73) compared to -1.90 (n = 1287, 95% CI: -1.99, -1.82) in the control group (P = 0.28).

CONCLUSIONS

An intervention to reduce AF exposure did not alter AF-alb nor anthropometric measures between treatment groups. Drought and agricultural data indicated less favorable conditions for toxin production, resulting in low levels of exposure in both trial arms. Annual, seasonal, and geographic heterogeneity of AF contamination make it difficult to study in an ethically designed trial. Our formative research and early trial data indicate that stunting and intermittent AF exposure continue to be a problem in this region. However, the low-AF exposure levels during the trial led to inconclusive results.

TRIAL REGISTRATION NUMBER

NCT03940547 (ClinicalTrials.org).

Modeling maize aflatoxins and fumonisins in a Tanzanian smallholder system: Accounting for diverse risk factors improves mycotoxin models

Human exposure to mycotoxins is common and often severe in underregulated maize-based food systems. This study explored how monitoring of these systems could help to identify when and where outbreaks occur and inform potential mitigation efforts. Within a maize smallholder system in Kongwa District, Tanzania, we performed two food surveys of mycotoxin contamination at local grain mills, documenting high levels of aflatoxins and fumonisins in maize destined for human consumption. A farmer questionnaire documented diverse pre-harvest and post-harvest practices among smallholder farmers. We modeled maize aflatoxins and fumonisins as a function of diverse indicators of mycotoxin risk based on survey data, high-resolution geospatial environmental data (normalized difference vegetation index and soil quality), and proximal near-infrared spectroscopy. Interestingly, mixed linear models revealed that all data types explained some portion of variance in aflatoxin and fumonisin concentrations. Including all covariates, 2015 models explained 27.6% and 20.6% of variation in aflatoxin and fumonisin, and 2019 models explained 39.4% and 40.0% of variation in aflatoxin and fumonisin. This study demonstrates the value of using low-cost risk factors to model mycotoxins and provides a framework for designing and implementing mycotoxin monitoring within smallholder settings.

Nutrient Intake and Dietary Adequacy Among Rural Tanzanian Infants Enrolled in the Mycotoxin Mitigation Trial

BACKGROUND

The Mycotoxin Mitigation Trial (MMT) was a community-based cluster-randomized trial designed to assess the effect of dietary aflatoxin (AF) on linear growth. Similar dietary intake between arms was an important component of the trial's program theory and essential for the trial's internal validity and interpretation.

OBJECTIVE

This analysis assessed and compared dietary intake by arm within a sub-sample of infants enrolled in the MMT.

METHODS

Twenty paired clusters (10 per trial arm) out of the 52 MMT clusters were included in this sub-sample. Up to 15 maternal/infant dyads per cluster were randomly selected for a one-time, structured, multi-pass 24 h dietary recall. Data were collected at the midpoint of the trial, when infants were 12 months of age, over 8 calendar months. We evaluated and compared infant nutrient intake and adequacy of energy, protein, lipid, iron, zinc, calcium, and vitamin A between study arms. Nutrient intake by arm was estimated using mixed-level regression models.

RESULTS

A total of 282 mothers participated (n = 140 intervention arm and 142 standard of care (SoC) arm). The mean daily intakes of energy and lipid fed to infants were 505 kcal/day (SD = 225.9) and 13 g/day (SD = 6.9), respectively, in the intervention and SoC arms, with no difference between arms. Intervention infants consumed slightly more protein than SoC infants (13.7 v. 12.3 g/day, p = 0.02). Consumption of iron, zinc, calcium, and vitamin A were low and did not differ between arms.

CONCLUSIONS

At the midpoint of the MMT, energy, lipid, and micronutrient intake did not differ between arms. Protein consumption was slightly greater in the intervention arm. Guided by the trial's program theory, this analysis advances the interpretation of the MMT trial findings.

Comparison of Methods to Assess Adherence to Infant and Young Child Feeding Practices and Provision of Low-Aflatoxin Porridge Flours in a Community-Based Intervention Trial

BACKGROUND

Levels of adherence to recommended protocols in an intervention trial can affect outcomes and confound the results. To broaden the evidence about the selection and utility of adherence measures in varying contexts, we describe the level of adherence to the Mycotoxin Mitigation Trial (MMT) randomized intervention using caregiver-reported survey questions and compare inferences of adherence between multi-module surveys and interactive 24 h dietary recalls based on our program theory.

METHODS

The MMT was a two-arm cluster-randomized trial conducted in 52 health facilities (clusters) in central Tanzania. Surveys were conducted with all trial participants at three time points and dietary recalls were conducted in a cohort at 12 mo.

RESULTS

The 12 mo survey was conducted with 2112 caregivers and the 18 mo survey was conducted with 2527 caregivers. A cohort of participants (n = 282, 20 clusters) was selected for dietary recalls, balanced by arm. Reported feeding of blended porridge flours, whether MMT-provided or own-sourced, was high at 12 and 18 mo, between 73 and 95%, with only slight differences between the surveys and recalls. Inferences were similar for continuation of breastfeeding, feeding frequency, and dietary diversity. Only the amount of porridge fed the previous day differed statistically by method, with higher amounts reported in the recalls compared to the survey.

CONCLUSIONS

Detailed analysis of reported behaviors, based on the MMT program theory, supports high adherence to the recommended trial behaviors. Survey data and 24 h dietary recalls were convergent for almost all indicators, strengthening the trial's conclusions and allowing for either method to be selected for similar research.

Processing complementary foods to reduce mycotoxins in a medium scale Tanzanian mill: A hazard analysis critical control point (HACCP) approach

Designing and implementing processing procedures for producing safe complementary foods in dynamic and unregulated food systems where common food staples are frequently contaminated with mycotoxins is challenging. This paper presents lessons about minimizing aflatoxins (AF) in groundnut flour and AF and/or fumonisins (FUM) in maize and groundnut pre-blended flour for complementary feeding in the context of a dietary research intervention in rural Tanzania. The flours were processed in collaboration with Halisi Products Limited (Halisi), a medium scale enterprise with experience in milling cereal-based flours in Arusha, Tanzania. Using a hazard analysis critical control point (HACCP) approach for quality assurance, two critical control points (CCPs) for AF in processing the pre-blended flour were identified: 1) screening maize before procurement, and 2) blending during the processing of each constituent flour. Blending of maize flour was also identified as a CCP for FUM. Visual inspection during screening and sorting were identified as important control measures for reducing AF, but these steps did not meet the criteria for a CCP due to lack of objective measurement and verifiable standards for AF. The HACCP approach enabled the production of low AF (<5 μg/kg) and FUM (<2 μg/g) flours with low rejection rates for the final products. The paper presents practical lessons that could be of value to a range of commercial processors in similar low- and middle-income contexts who are keen on improving food quality.

Advancing Global Health Surveillance of Mycotoxin Exposures using Minimally Invasive Sampling Techniques: A State-of-the-Science Review

Mycotoxins are a heterogeneous group of toxins produced by fungi that can grow in staple crops (e.g., maize, cereals), resulting in health risks due to widespread exposure from human consumption and inhalation. Dried blood spot (DBS), dried serum spot (DSS), and volumetric tip microsampling (VTS) assays were developed and validated for several important mycotoxins. This review summarizes studies that have developed these assays to monitor mycotoxin exposures in human biological samples and highlights future directions to facilitate minimally invasive sampling techniques as global public health tools. A systematic search of PubMed (MEDLINE), Embase (Elsevier), and CINAHL (EBSCO) was conducted. Key assay performance metrics were extracted to provide a critical review of the available methods. This search identified 11 published reports related to measuring mycotoxins (ochratoxins, aflatoxins, and fumonisins) using DBS/DSS and VTS assays. Multimycotoxin assays adapted for DBS/DSS and VTS have undergone sufficient laboratory validation for applications in large-scale population health and human biomonitoring studies. Future work should expand the number of mycotoxins that can be measured in multimycotoxin assays, continue to improve multimycotoxin assay sensitivities of several biomarkers with low detection rates, and validate multimycotoxin assays across diverse populations with varying exposure levels. Validated low-cost and ultrasensitive minimally invasive sampling methods should be deployed in human biomonitoring and public health surveillance studies to guide policy interventions to reduce inequities in global mycotoxin exposures.

Provision of low-aflatoxin local complementary porridge flour reduced urinary aflatoxin biomarker in children aged 6-18 months in rural Tanzania

Aflatoxins are toxic secondary metabolites of fungi that colonize staple food crops, such as maize and groundnut, frequently used in complementary feeding. In preparation for a large trial, this pilot study examined if provision of a low-aflatoxin infant porridge flour made from local maize and groundnuts reduced the prevalence of a urinary aflatoxin biomarker in infants. Thirty-six infants aged 6-18 months were included from four villages in Kongwa District, Tanzania. The study was conducted over 12 days with a three-day baseline period and a 10 days where low-AF porridge flour was provided. Porridge intake of infants was assessed using quantitative 24-h recalls by mothers. Household food ingredients used in infant porridge preparation and urine samples were collected on Days 1-3 (baseline) and 10-12 (follow-up). Aflatoxins were measured in household foods, and AFM1 was measured in urine. At baseline and follow-up, 78% and 97%, respectively, of the infants consumed porridge in the previous 24 h, with a median volume of 220 mL (interquartile range [IQR]: 201, 318) and 460 mL (IQR: 430, 563), respectively (p < 0.001). All 47 samples of homemade flour/ingredients were contaminated with AFs (0.3-723 ng/g). The overall prevalence of individuals with detectable urinary AFM1 was reduced by 81%, from 15/36 (42%) at baseline to 3/36 (8%) at follow-up (p = 0.003). Provision of low-aflatoxin porridge flour was acceptable to caregivers and their infants and successfully reduced the prevalence of detectable urinary AFM1 in infants, thus, confirming its potential to be tested in future large-scale health outcomes trial.

Human Breast Milk Contamination with Aflatoxins, Impact on Children's Health, and Possible Control Means: A Review

Aflatoxins are natural toxicants produced mainly by species of the Aspergillus genus, which contaminate virtually all feeds and foods. Apart from their deleterious health effects on humans and animals, they can be secreted unmodified or carried over into the milk of lactating females, thereby posing health risks to suckling babies. Aflatoxin M1 (AFM1) is the major and most toxic aflatoxin type after aflatoxin B1 (AFB1). It contaminates human breast milk upon direct ingestion from dairy products or by carry-over from the parent molecule (AFB1), which is hydroxylated in the liver and possibly in the mammary glands by cytochrome oxidase enzymes and then excreted into breast milk as AFM1 during lactation via the mammary alveolar epithelial cells. This puts suckling infants and children fed on this milk at a high risk, especially that their detoxifying activities are still weak at this age essentially due to immature liver as the main organ responsible for the detoxification of xenobiotics. The occurrence of AFM1 at toxic levels in human breast milk and associated health conditions in nursing children is well documented, with developing countries being the most affected. Different studies have demonstrated that contamination of human breast milk with AFM1 represents a real public health issue, which should be promptly and properly addressed to reduce its incidence. To this end, different actions have been suggested, including a wider and proper implementation of regulatory measures, not only for breast milk but also for foods and feeds as the upstream sources for breast milk contamination with AFM1. The promotion of awareness of lactating mothers through the organization of training sessions and mass media disclosures before and after parturition is of a paramount importance for the success of any action. This is especially relevant that there are no possible control measures to ensure compliance of lactating mothers to specific regulatory measures, which can yet be appropriate for the expansion of breast milk banks in industrialized countries and emergence of breast milk sellers. This review attempted to revisit the public health issues raised by mother milk contamination with AFM1, which remains undermined despite the numerous relevant publications highlighting the needs to tackle its incidence as a protective measure for the children physical and mental health.

Ethical considerations in the design and conduct of a cluster-randomised mycotoxin mitigation trial in Tanzania

Aflatoxins are fungal metabolites that commonly contaminate staple food crops in tropical regions. Acute aflatoxin consumption in very high concentration causes aflatoxicosis and acute liver failure, while chronic, moderate levels of intake cause hepatocellular carcinoma. The effects of frequent moderate- to high-level exposure during infancy, however, is less clearly understood. Half a billion people in low- and middle-income countries continue to be exposed to aflatoxins through dietary consumption, in part because of lack of enforcement of regulatory limits and few feasible long-term mitigation options in these settings. Several epidemiologic studies have shown an association between aflatoxin exposure in infants and young children and growth failure, but strong experimental evidence is lacking. The Mycotoxin Mitigation Trial conducted in Tanzania was a cluster-randomised trial to assess the effect of a reduced aflatoxin diet on linear growth. Prior to the design and implementation of this trial, a group of multi-disciplinary and multi-national scientists reviewed literature in biomedical, public health, environmental health ethics. In this paper we outline the most salient ethical questions and dilemmas in the potential conduct of such a study and describe the ethical precedents and principles that informed our decision-making processes and ultimate study protocol.

Development and Limitations of Exposure Biomarkers to Dietary Contaminants Mycotoxins

Mycotoxins are toxic secondary fungal metabolites that frequently contaminate cereal crops globally, presenting exposure hazards to humans and livestock in many settings. The heterogeneous distribution of mycotoxins in food restricts the usefulness of food sampling and intake estimates for epidemiological studies, making validated exposure biomarkers better tools for informing epidemiological investigations. While biomarkers of exposure have served important roles for understanding the public health impact of mycotoxins such as aflatoxins (AF), the science of biomarkers must continue advancing to allow for better understanding of mycotoxins' roles in the etiology of disease and the effectiveness of mitigation strategies. This review will discuss mycotoxin biomarker development approaches over several decades for four toxins of significant public health concerns, AFs, fumonisins (FB), deoxynivalenol (DON), and ochratoxin A (OTA). This review will also highlight some knowledge gaps, key needs and potential pitfalls in mycotoxin biomarker interpretation.

Nutritional Status and Growth Deficit in Children and Adolescents with Cancer at Different Moments of Treatment

BACKGROUND

Nutrition deficits are common in children and adolescents undergoing cancer treatment and can contribute to a worse prognosis. There are scarce studies regarding this context considering different moments of treatment. The aim of this study was to evaluate the association between moment of treatment and nutritional status in children and adolescents with cancer.

METHODS

A retrospective study was performed from January 2013 to December 2015, including data from all clinical records of patients under 18 years old with cancer. Clinical, nutritional support and anthropometric data were collected at four moments of treatment from cancer diagnosis: diagnosis (t₀), 3 mo, (t₁), 6 mo, (t₂) and 1 year (t₃). In addition, nutritional indicators were evaluated. Generalized Estimating Equation models were performed to analyze changes on anthropometric indices throughout four moments of treatment.

RESULTS

The sample comprised 73 patients and frequency of nutritional deficits ranged from 13.0% to 18.6%. All nutritional indicators decreased at t₁, showed a modest recovery at t₂ and a stronger recovery at t₃ (p < 0.001). Growth was also impacted during treatment, mainly on patients under 2 years in the first three months of treatment.

CONCLUSIONS

Moment of treatment was associated with growth deficit and decreased percentiles in development indicators.