Effects of an antioxidant beverage on biomarkers of oxidative stress in Alzheimer's patients.

Abstract

The purpose of the study was to test whether daily consumption of a beverage with high antioxidant power, combining extracts of green tea and apple over a period of 8months, would affect blood and urinary concentrations of biomarkers of oxidative stress in Alzheimer's patients. The study included 100 subjects, 48 of them were Alzheimer's patients, aged 76.5±3.5years, and 52 were control subjects, aged 79±4years, without dementia. Three blood and urine samples were taken from each participant, the first (T i) before starting the antioxidant or placebo beverage intake, the second (T m) 4months after the antioxidant or placebo beverage intake and the third (T f) 8months after the antioxidant or placebo beverage intake, and concentrations of biomarkers of oxidative stress were measured on serum, lysed erythrocytes or urine by UV-Vis spectrophotometry or by competitive in vitro enzyme-linked immunosorbent assay, according to the parameter analyzed. The administration of the antioxidant beverage to the Alzheimer's patients prevented the decrease in total antioxidant status in the moderate phase of the disease (T i=1.40±0.10mmol/L vs T f=1.20±0.08mmol/L), increased values of glutathione peroxidase and superoxide dismutase in initial (165 and 24% respectively) and moderate phase (75 and 85% respectively), and prevented the increase in protein carbonyls in moderate phase (T i=0.17±0.07nmol/mg protein vs T f=0.21±0.06nmol/mg protein), with a significant decrease in protein carbonyls since the fourth month of the intake in initial phase (T m=0.21±0.06nmol/mg protein vs T f=0.11±0.05nmol/mg protein). Our results suggest that antioxidant beverage could be used as a natural complementary therapy for alleviate or decrease the oxidative stress effects in the stages of Alzheimer's disease.