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

Background: Maize is frequently contaminated by aflatoxin B₁ (AFB₁), an established liver carcinogen.

Objective: To estimate the effect of maize and maize tortilla consumption on AFB₁-lysine adduct (AFB₁-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 years living in south and eastern Mexico in 2018-19. 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. AFB₁-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 AFB₁-lysine adduct by fitting linear regression models that accounted for the complex survey design.

Results: Median maize intake was 307 grams/day (Quartile 1 [Q1]-Quartile 3 [Q3] = 165, 554). Maize tortillas represented 77% of total maize consumption, with a median consumption of 252 grams per day (Q1-Q2 = 120, 462). After multivariable adjustment, for every 30 grams of maize consumed (one tortilla equivalent), circulating AFB₁-lys incremented by 2.1% (95% 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 were minimal.

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