Aflatoxins, toxins produced by Aspergillus fungi, pose a significant health risk, particularly in South Asia where women and young children are vulnerable to exposure through contaminated food. Acute aflatoxicosis can be fatal, while chronic, low-level exposure is linked to impaired growth and other health problems. Aflatoxins contaminate various foods, including maize, chilies, spices, oilseeds, and nuts, and are challenging to detect and remove. Resource-scarce populations, with limited dietary variety and reliance on aflatoxin-prone foods, are at increased risk. Improved dietary diversity has been suggested as a potential mitigation strategy. This study aimed to determine the association between aflatoxin exposure during pregnancy in Nepali women and the frequency of consumption of susceptible foods, dietary diversity, and seasonality. The context is crucial because Nepal has high rates of aflatoxin contamination and a largely rice-based diet where other foods may serve as significant sources of aflatoxin exposure. Understanding these dietary factors is essential for developing effective interventions to reduce aflatoxin exposure and improve maternal and child health. The importance of this research lies in identifying specific dietary contributors to aflatoxin exposure, which can inform targeted public health interventions to protect vulnerable populations.

Existing literature highlights the significant health risks associated with aflatoxin exposure, particularly in vulnerable populations. Studies have shown the placental transfer of aflatoxin from mother to fetus and its links to impaired linear growth in children. The susceptibility of various food commodities, such as maize and groundnuts, to aflatoxin contamination has been well-documented. The challenges in detecting and removing aflatoxins, due to their resistance to thermal inactivation and invisibility to consumers, are also widely acknowledged. Previous research suggests a potential role for improved dietary diversity in reducing aflatoxin exposure by decreasing reliance on contaminated foods. However, the specific dietary determinants and their interaction with seasonality remain areas needing further investigation. This review forms the basis for the hypotheses tested in the current study regarding the relationship between food consumption patterns, dietary diversity, seasonality and aflatoxin exposure in pregnant Nepali women.

This study used data from the AflaCohort Birth Cohort Study (2015-2019) conducted in Banke, Nepal. 1675 healthy pregnant women were enrolled using a rolling recruitment strategy. The sample size was calculated to detect a specified difference in postnatal height-for-age Z-scores. Data collection involved administering electronic surveys with 7-day and 24-h food frequency questionnaires (FFQs) to assess the frequency of consumption of 49 food items. Height, weight, and mid-upper arm circumference (MUAC) were measured. Serum samples were collected and analyzed for AFB₁-lys adducts using high-performance liquid chromatography (HPLC) with fluorescence detection. Minimum Dietary Diversity for Women of Reproductive Age (MDD-W) guidelines were used to calculate minimum dietary diversity scores. Covariates included age, education, wealth status, MUAC, season, and Village Development Committee. Statistical analyses included ordinary least squares (OLS) and quantile regression (QR) models to examine the association between food consumption, dietary diversity, seasonality, and AFB₁-lys adduct levels. Data were divided into quintiles of aflatoxin B₁-lys adducts. Non-normally distributed data were log-transformed. Two-sided Student's t-tests, analysis of variance, chi-squared tests, and restricted cubic splines were employed. The analysis included adjustments for potential confounders identified through the dataset.

Aflatoxin exposure was widespread, with 94% of women showing detectable AFB₁-lys adducts (geometric mean 1.37 pg/mg). Maize and groundnut consumption were significantly positively associated with AFB₁-lys adduct levels, particularly in higher exposure quantiles. For every additional occasion of weekly maize consumption, women in the 30th, 50th, and 70th quantiles of exposure showed increases in AFB₁-lys adduct levels (p<0.05). Similar significant increases were observed in groundnut consumption across various exposure quantiles. Winter month recruitment showed a positive association with AFB₁-lys adduct levels across all quantiles (p<0.001). Annual milk consumption was positively associated with AFB₁-lys adduct concentrations. Contrary to expectations, dietary diversity was not significantly associated with aflatoxin exposure, except in the lowest exposure quantile. The study also noted the high prevalence of rice consumption in the participants' diet.

The findings demonstrate a strong association between consumption of maize and groundnuts and aflatoxin exposure in pregnant Nepali women. This aligns with previous research indicating the common contamination of these commodities. The seasonal variation in aflatoxin exposure, with higher levels in winter, suggests environmental factors affecting aflatoxin production and/or food storage practices. The unexpected lack of association between dietary diversity and aflatoxin exposure suggests that simply increasing dietary diversity may not be sufficient to reduce aflatoxin exposure. The positive association between milk consumption and aflatoxin levels highlights indirect routes of exposure. The study's limitations include potential recall bias in the FFQ and the absence of direct aflatoxin M1 measurements in milk samples. This emphasizes the need for multi-pronged interventions targeting both food production and consumption practices to effectively reduce aflatoxin exposure. Further research should investigate other food sources of aflatoxin contamination within the Nepali diet and explore the efficacy of specific interventions.

This study highlights the significant dietary determinants of aflatoxin exposure among pregnant Nepali women, emphasizing the role of maize and groundnuts and the influence of seasonality. The lack of association between dietary diversity and aflatoxin exposure suggests the need for targeted interventions beyond simple diversification. Future research should focus on evaluating specific interventions to reduce aflatoxin contamination in staple foods and improving food safety practices. Further investigation into the role of other commonly consumed foods and indirect exposure routes is warranted.

The study's reliance on self-reported food consumption data through FFQs could introduce recall bias. The study did not directly measure aflatoxin M1 in milk, only relying on reported milk consumption. The study's focus on a single geographic region in Nepal limits the generalizability of the findings to other regions. The cross-sectional nature of the data limits the ability to establish causal relationships between dietary factors and aflatoxin exposure. Further research with longitudinal data would be valuable to better understand the dynamic relationship between diet and aflatoxin exposure over time.