Abstract
BackgroundFew randomized clinical trials have explored the health effects of bilberries in humans. The aim was to test the effect of bilberry and red grape-juice consumption on visual memory, motor speed and dexterity as well as inflammatory and tissue damage biomarkers of plasma in aged men with subjective memory impairment.MethodsNine-week double-blind, placebo-controlled, dietary intervention study of aged men (n = 60, age ≥ 67 years) with subjective memory impairment randomized to consume a 50/50 mix of bilberry/red grape-juice or an iso-caloric placebo juice. A selection of Cambridge Cognition Test Battery (CANTAB), Grooved Pegboard tests and blood-sampling for biomarker analysis were performed before and after the intervention.ResultsCompared to placebo the selected memory and motor test scores were un-affected by the bilberry/red grape intervention. However, the plasma levels of tissue damage biomarkers decreased significantly more in the bilberry/red grape group. In particular lactate dehydrogenase (LDH) decreased from 362 U/L (median, baseline) to 346 U/L (median, post intervention) in the bilberry/red grape group. Also, several biomarkers of inflammation (EGF, IL6, IL9, IL10 and TNFα) decreased significantly more in the bilberry/red grape group. Furthermore, several plasma polyphenols; p-coumaric acid, hippuric acid, protocatechuic acid, 3HPAA and vanillic acid, increased significantly more in the bilberry/red grape group compared to placebo with the largest increase in p-coumaric acid with 116%; from 2.2 [1.0,5.5] to 4.7 [2.8,8.1] μM/L (median [95% CL]).ConclusionsThe results indicate that a nine-week bilberry/red grape juice intervention has no measurable effects on the selected memory scores in aged men experiencing memory problems but decreases the level of biomarkers of inflammation and tissue damage. Whether the dampening effects on inflammation and tissue damage biomarkers have relevance for neuroinflammatory brain pathology remains to be established.Trial registrationRegistration number (ClinicalTrials.gov: NCT00972972), September 9, 2009.
Highlights
Few randomized clinical trials have explored the health effects of bilberries in humans
In epidemiological studies plant-rich diets have consistently been associated with lower risk of oxidative stress and inflammation associated diseases, such as Alzheimer’s disease (AD) [8] and the therapeutic potential for neuroprotective effects of natural compounds and plant-food has been studied in several clinical trials [9, 10]
When compared to the changes in the control group we find several plasma polyphenols to be significantly increased in the bilberry/red grape group (Table 4, Supplemental Fig. 2 B-F)
Summary
Few randomized clinical trials have explored the health effects of bilberries in humans. The aim was to test the effect of bilberry and red grape-juice consumption on visual memory, motor speed and dexterity as well as inflammatory and tissue damage biomarkers of plasma in aged men with subjective memory impairment. The pathology of AD is associated with increased oxidative damage and inflammation [7]. In epidemiological studies plant-rich diets have consistently been associated with lower risk of oxidative stress and inflammation associated diseases, such as AD [8] and the therapeutic potential for neuroprotective effects of natural compounds and plant-food has been studied in several clinical trials [9, 10]. Animal studies have shown that intake of plant food (e.g., blueberries, strawberries and spinach) can retard and even reverse age-related decline in brain function and cognitive and motor performance in rats [12]. A compound of pomegranate was found to increase the process of eliminating damaged mitochondria in the hippocampus of AD mice and improve learning and memory [13]
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