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.
Keywords: Lutein; Lycopene; Retinol; Zeaxanthin; α-Carotene; α-Tocopherol; β-Carotene; β-Cryptoxanthin; γ-Tocopherol.