Maize consumption and circulating aflatoxin levels in Mexican middle- and older-aged adults: a cross-sectional analysis.

Background: Maize is frequently contaminated by aflatoxin B (AFB), an established liver carcinogen.

Objectives: The objective of this study is to estimate the effect of maize and maize tortilla consumption on AFB-lysine adduct (AFB-lys) concentrations in middle- and older-aged adults living in south and eastern Mexico.

Methods: We conducted a cross-sectional analysis in a representative sample of 915 adults aged ≥40 y living in south and eastern Mexico in 2018-2019. Maize and maize tortilla intake were estimated using a food frequency questionnaire. Intake of maize tortillas made from store-purchased masa or bought in a tortilleria, from homemade masa, and from store-bought maize flour was assessed. AFB-lys in serum was quantified using state-of-the-art isotope-dilution liquid chromatography-mass spectrometry. We assessed the relationship between maize and maize tortilla consumption and AFB-lys by fitting linear regression models that accounted for the complex survey design.

Results: Median maize intake was 307 g/d [quartile 1 (Q1)-quartile 3 (Q3) = 165, 554]. Maize tortillas represented 77% of total maize consumption, with a median consumption of 252 g/d (Q1-Q2 = 120, 462). After multivariable adjustment, for every 30 g of maize consumed (1 tortilla equivalent), circulating AFB-lys incremented by 2.1% [95% confidence interval (CI): 0.9%, 3.4%]. For every maize tortilla consumed, the concentration of circulating AFB1-lys was 2.0% (95% CI: 0.6%, 3.4%) higher. The corresponding estimate for homemade masa tortilla was 2.8% (95% CI: 1.1%, 4.6%). The magnitude of the estimates for tortillas made from store-purchased masa or bought in a tortilleria and those made from store-bought maize flour was minimal.

Conclusions: Maize and maize tortilla intake was associated with AFB1-lys concentrations. This association appears to be driven by the consumption of tortillas made from homemade masa.