Serum concentrations of vitamin E and carotenoids are altered in Alzheimer's disease: A case-control study

INTRODUCTION Oxidative stress has been implicated in the pathogenesis of Alzheimer's disease (AD). We investigated associations between serum levels of lipophilic antioxidants and AD. METHODS Serum concentrations of retinol, two forms of vitamin E (α- and γ-tocopherol) and six carotenoids were quantified by high-performance liquid chromatography from patients with AD (n = 251) and cognitively intact controls (n = 308) and assessed by regression analyses. RESULTS Serum levels of α-tocopherol and all six carotenoids were significantly lower in patients with AD compared with cognitively intact controls (P < .001). In contrast, γ-tocopherol was significantly higher in the serum of patients with AD (odds ratio = 1.17 [confidence intervals: 1.05-1.31]). DISCUSSION Our findings implicate compromised serum antioxidant defenses in AD pathogenesis and differing biological roles for vitamin E isoforms. This highlights the need for improved understanding in the balanced upregulation of exogenous antioxidants related to dietary intake or supplement use in future nutritional intervention studies.