Habitual intake of iron, copper, and zinc and the risk of type 2 diabetes in a prospective cohort: The CAVAS (Cardiovascular Disease Association Study).

BACKGROUND AND AIMS: Unlike iron, evidence of the association between dietary copper and zinc intake and type 2 diabetes (T2D) risk is limited. This study aimed to examine the prospective associations of dietary intake of iron (total, plant-based, and animal-based), copper, and zinc with T2D risk among adults aged ≥40 years.

METHODS AND RESULTS: For 16,666 participants, dietary intakes (baseline, cumulative average, and most recent) of iron, copper, and zinc were calculated from repeated food frequency questionnaires; a modified Poisson regression model with a robust error estimator was conducted. In men, positive associations between T2D and baseline dietary intake of Cu and Zn, cumulative average dietary intake of Fe (total and animal-based), Cu and Zn, and most recent dietary intake of Fe (total, plant-based, and animal-based), Cu, and Zn [most recent diet: for total Fe, IRR(95%CI) = 1.93 (1.41-2.64); for plant-based Fe, 1.56 (1.15-2.11); for animal-based Fe, 1.44 (1.09-1.90); for Cu, 3.17 (2.33-4.30); for Zn, 2.18 (1.64-2.89)] were observed, where as in women, there were positive associations of only cumulative average dietary Zn intake and most recent dietary intake of plant-based Fe, Cu, and Zn [most recent diet: for plant-based Fe, 1.30 (1.01-1.68); for Cu, 1.62 (1.27-2.08); for Zn, 2.07 (1.61-2.66)].

CONCLUSION: Dietary intakes of iron (total, plant-based, and animal-based), copper, and zinc may be positively associated with T2D risk. These positive associations are predominantly observed in most recent diet and appear to be stronger compared to baseline and cumulative average diet.