The effect of diet on vascular responses to mental stress

Baynham, Rosalind Layla ORCID: 0000-0001-5234-2369 (2024). The effect of diet on vascular responses to mental stress. University of Birmingham. Ph.D.

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Abstract

Stress is increasingly prevalent in society. There is evidence that mental stress is related to an increased risk for cardiovascular disease, and can trigger myocardial infarction and stroke. Vascular responses to stress have been implicated as an underlying mechanism. Stress also influences health behaviours, such as dietary choices and physical activity. Specific nutrients and engagement in physical activity have been shown to influence the vasculature, yet their effect on peripheral and cerebral vascular function in the context of mental stress is unclear. A scoping review first established literature investigating the impact of dietary interventions on vascular responses to mental stress (Chapter 2). Following a repeatability study (Chapter 3) for the primary assessment of endothelial function (brachial flow-mediated dilatation) and ultrasound assessment of cerebral vasculature (common carotid artery blood flow), this thesis investigated the effect of saturated fat and flavonoid-rich cocoa interventions on vascular responses during stress and endothelial function following mental stress in a healthy population (Chapters 4 – 6). The relationship between stress and health behaviours was then explored in a free-living environment (Chapters 7 – 8). The findings of this thesis reported saturated fat consumption to impair the recovery of endothelial function following stress and attenuate cerebral oxygenation during stress. Furthermore, consuming flavonoid-rich cocoa with saturated fat counteracted the negative impact of fat consumption on the stress-induced decline in endothelial function. However, flavonoid-rich cocoa did not influence cerebral oxygenation during stress following fat consumption. In a free-living environment, the data suggests perceived stress positively associated with flavonoid consumption. Similarly, stress-related psychological outcomes (positivity and fatigue) were positively related to consumption of fat, saturated fat, and sugar. Stress was not associated with engagement in physical activity yet engaging in physical activity associated with improved perceptions of coping with stress and feeling more on top of things. The findings of this thesis suggest that health behaviours adopted during periods of stress may worsen or mitigate the impact of stress on vascular function and modify how we psychologically cope with stress. Future work is required to understand how to drive behaviour change to gain the most vascular protection during stress or, alternatively, investigate the potential of chronic dietary and exercise interventions to build vascular resilience during periods of heightened stress.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):