Effects of cocoa flavanols on peripheral blood flow and symptoms in primary Raynaud’s phenomenon

Wan Ghazali, Wan Syaheedah (2021) Effects of cocoa flavanols on peripheral blood flow and symptoms in primary Raynaud’s phenomenon. PhD thesis, University of Nottingham.

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Primary Raynaud’s phenomenon (PRP) is characterised by the periodic vasospasm of the digits precipitated by exposure to cold/emotional stimuli. PRP may involve vascular endothelium dysfunction, abnormalities in neural control of vascular tone and/or increases in circulating mediators which promote vasoconstriction. Cocoa products have been shown to promote vasodilation, and therefore could mitigate PRP symptoms. The work described in this thesis investigates the effects of cocoa flavanols on peripheral blood flow, thermoregulation and symptoms in people with PRP.

The acute effects of high flavanol cocoa (HFC) consumption on cardiovascular parameters and peripheral thermoregulation was compared between people with PRP and control participants using a double blind, cross over design. The chronic effects of 3 months daily consumption of HFC was then investigated using a double blind, placebo-controlled, parallel group design in people with PRP. The experiencing of Raynaud’s symptoms, their duration and level of pain, and an assessment of Raynaud’s Condition Score were documented by participants in a symptoms diary throughout the intervention. Dietary macronutrient composition as well as total flavanol and epicatechin intake, were assessed monthly using diet diaries and Food Frequency Questionnaires, respectively, with Physical and Mental Health status being determined at these time points using the SF-36TM. A Finometer was used to measure cardiovascular variables and Laser Doppler Flowmetry used to assess skin blood flow before and after the supplementation period. In pilot studies, FMD was used to determine endothelial function following HFC consumption.

Data from the pilot studies found that acute consumption of a HFC drink induces a greater vasodilatory response to a shear stress stimulus at 1hr compared to a LFC drink. In acute supplementation studies, it was found that consumption of a HFC drink did not impact peripheral thermoregulation in either PRP participants or controls. Meanwhile, consumption of HFC capsules in a chronic supplementation study reduced total peripheral resistance and increased cardiac output, but these beneficial effects were not accompanied by an increase in skin blood flow, or improvements in Raynaud’s symptoms among PRP participants. It was also observed that in this cohort, having PRP did not appear to negatively impact mental or physical wellbeing, compared to a general population. The thesis proposes that it is feasible to recruit, retain, and provide follow-up with the participants for a full randomised control trial involving individuals with PRP in the future.

The findings from acute supplementation studies demonstrated no differential effect of HFC drink on cardiovascular measures and skin blood flow in either PRP participants or controls, while data from chronic supplementation study found no differential effect of HFC capsules on skin blood flow and Raynaud’s symptoms among PRP participants. Therefore, it is important that people with PRP are aware that cocoa flavanols probably will not help to reduce their symptoms, despite studies that suggest their consumption improves the compliance of resistance vessels and microvasculature in healthy individuals.

Item Type: Thesis (University of Nottingham only) (PhD)
Supervisors: Macdonald, Ian
Simpson, Liz
Keywords: Primary Raynaud’s phenomenon, High flavanol cocoa
Subjects: Q Science > QP Physiology
Faculties/Schools: UK Campuses > Faculty of Medicine and Health Sciences > School of Life Sciences
Item ID: 63824
Depositing User: Wan Ghazali, Wan
Date Deposited: 31 Jul 2021 04:40
Last Modified: 01 Aug 2021 04:30
URI: http://eprints.nottingham.ac.uk/id/eprint/63824

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