The impact of cranberry polyphenols on the brain and gut microbiome in healthy ageing

Flanagan, Emma (2021) The impact of cranberry polyphenols on the brain and gut microbiome in healthy ageing. Doctoral thesis, University of East Anglia.

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Ageing is associated with increasing risk of cognitive decline, and modifiable lifestyle factors including diet have been shown to significantly affect the progression of age-related neurodegeneration. Specific dietary components, particularly polyphenol-rich berries such as cranberries, have been increasingly recognised for their effects on the mechanisms underlying age-related neurodegeneration, including the alteration of the gut microbiome and its functions. However, the impact of cranberries on cognition, brain function and the gut microbiome in healthy older adults remains little explored. A 12-week randomised placebo-controlled trial of freeze-dried cranberry powder was conducted in 60 healthy older adults aged between 50 and 80 years. Cognitive assessment, including memory and executive function, neuroimaging, and blood, stool and urine sample collection were conducted before and after the intervention to assess the impact of daily cranberry consumption on cognition, brain function, and the structure and function of the gut microbiome. Cranberry supplementation significantly improved visual episodic memory, with mechanisms of action underpinned by increased regional perfusion in the right entorhinal cortex, the nucleus accumbens area and the caudate. A beneficial shift in microbial abundances in bacterial families relating to polyphenol degradation was also detected in the cranberry group, which correlated with increased levels of circulating polyphenol metabolites in plasma. Gut bacteria-derived metabolites such as TMAO and hippuric acid were also significantly related to improved episodic memory in the cranberry group, although common polyphenol metabolites did not relate to cognitive performance or brain perfusion. These results indicate that daily cranberry supplementation over a 12-week period improved episodic memory performance and neural functioning, corresponding with a beneficial shift in the composition and function of the gut microbiome. These findings provide a basis for future investigations to determine efficacy of intake of high-polyphenol cranberry in the context slowing the onset of neurodegenerative diseases, such as Alzheimer’s disease.

Item Type: Thesis (Doctoral)
Faculty \ School: Faculty of Medicine and Health Sciences > Norwich Medical School
Depositing User: Chris White
Date Deposited: 15 Feb 2023 10:33
Last Modified: 15 Feb 2023 10:33

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