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Title: The effect of pomegranate on anthropometric, biochemical, cognitive and satiety indicators of risk factors for non-communicable diseases
Author: Stockton, Angela
ISNI:       0000 0004 7966 6138
Awarding Body: Queen Margaret University, Edinburgh
Current Institution: Queen Margaret University
Date of Award: 2019
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Non-communicable diseases (NCDs) such as cardiovascular, endocrine, metabolic and cerebrovascular diseases are increasing contributors to, and major causes of worldwide morbidity and mortality. Hypertension and obesity are the most preventable cardiovascular risk factors which can be modified by diet and lifestyle changes. The pomegranate, valued as a medicinal fruit since antiquity, and its extract (PE), are both rich in polyphenol antioxidants which have the potential to improve both the management and outcomes of chronic disease, to decrease blood pressure and increase satiety, thus assisting in the reduction of cardiovascular disease (CVD), overweight and obesity. Chronic pomegranate supplementation has recently been shown to improve memory retention, and verbal memory with increased functional brain activity during visual and verbal memory tasks. PE consumption may perform a role in enhancing cognitive performance or towards preventing cognitive decline. The primary aims of this research were to investigate the effects of PE on BP and stress hormones, and to explore the relationship between PE intake and satiety, anthropometry, quality of life (QoL) and cognitive function indicators. Four studies were conducted in healthy volunteers to fulfil these aims using double-blind, placebo-controlled, RCT designs. The first three parallel studies were conducted over 4 and 8 weeks. The exploratory (Pom-01; n=29), satiety (Pom-01s; n=29) and blood pressure and anthropometry (Pom-02; n=55) studies investigated the effect of PE consumption on anthropometric, physiological, biochemical, satiety and QoL parameters. The fourth crossover RCT (Pom-03; n=20) explored the acute effect of PE on cognitive function. In Pom-01, paired t-tests showed that systolic BP was significantly reduced following PE intake (4.75 mmHg; p = 0.012), with reductions in diastolic BP (1.73 mmHg; p˃0.05). Levels of HOMA-IR (p = 0.045), glucose, insulin and uric acid all decreased. No significant changes were recorded in volunteers taking the placebo (PL). ANOVA indicated no significant differences between the groups. PE consumption caused a highly significant drop in salivary cortisol levels (p = 0.016 to p < 0.001), and the cortisol/cortisone ratio was also significantly reduced (p = 0.011 to p < 0.001). The RAND 36 QoL questionnaire showed significant improvements in physical (p = 0.018) and social functioning (p = 0.021), pain (p = 0.003), general health (p = 0.008) and overall QoL score (p = 0.007) over the 4-week study within the PE group compared to no significant changes in these parameters within the PL. In Pom-01s, volunteers taking PE reported feeling less hungry, with less desire to eat, felt fuller and more satisfied, and ate less (p = 0.05) than those who consumed the PL. There was a significant difference between the PE and PL groups in Pom-02 for diastolic BP (F2, 102 =4·4; p = 0·02), where PE decreased (2.79mmHg) compared to placebo. There was a similar non-significant decrease in magnitude of SBP (2.6mmHg) compared to PL. The QoL questionnaire, showed that significant improvements were also found in four parameters for the PE group between baseline and 8 weeks: energy (p = 0.017), emotional well-being (p = 0.003), social functioning (p = 0.046) and the overall QoL score (p = 0.022). There were no significant differences in the PL group. Acute PE ingestion in Pom-03 improved aspects of cognitive performance in healthy adults (Picture Recognition, p = 0.026; overall logical reasoning reaction time (RT), p < 0.001; serial subtraction, p < 0.001) compared to the non-biophenol PL. These results suggest that PE intake could be useful for public health. It may ameliorate non-communicable disease risk factors, reducing stress and blood pressure levels, improving cardiovascular health, perceived health related quality of life and aspects of cognitive function. The concurrent ability to decrease insulin resistance and modulate indicators of satiety could be of benefit to those who suffer from diabetes (type 2), metabolic syndrome or obesity. Future dietary intervention RCTs should focus on PE treatment effects over time and explore the most effective dosages in different population groups, age and body composition ranges.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available