Vitamin E intake is associated with lower brain volume in haptoglobin 1-1 elderly with type 2 diabetes

Background: The efficacy of vitamin E in prevention of diabetes-related complications differs by Haptoglobin (Hp) genotype. Objective: To examine the role of Hp genotype in the relationship of vitamin E intake with brain volume in cognitively normal elderly patients with type 2 diabetes. Methods: Brain volumes for the superior, middle, and inferior frontal gyri and for the middle temporal gyrus were generated from structural T1 MRI in 181 study participants (Hp 1-1: n = 24, Hp 2-1: n = 77, Hp 2-2: n = 80). Daily vitamin E intake was assessed using the Food Frequency Questionnaire. Analyses of covariance, controlling for demographic and cardiovascular variables was used to evaluate whether the association of daily vitamin E intake with brain volume was modified by Hp genotype. Results: Average age was 70.8 (SD = 4.2) with 40% females, and mean Mini-Mental State Examination score of 28.17 (SD = 1.90). A significant interaction was found between vitamin E intake and Hp genotype in inferior frontal gyrus' volume; p = 0.0108. For every 1 microgram increase in vitamin E intake, the volume of the inferior frontal gyrus decreased by 0.955% for Hp 1-1 (p = 0.0348), increased by 0.429% for Hp 2-1 (p = 0.0457), and by 0.077% for Hp 2-2 (p = 0.6318). There were no significant interactions between vitamin E intake and Hp genotype for the middle (p = 0.6011) and superior (p = 0.2025) frontal gyri or for the middle temporal gyrus (p = 0.503). Conclusions: The effect of dietary vitamin E on the brain may differ by Hp genotype. Studies examining the impact of vitamin E on brain-related outcomes should consider Hp genotype.