Flavanol-rich dark chocolate (DC) and green tea extract capsules (GT) were assessed for effects on markers of vascular health. Commercially available dark chocolate was analysed for flavanol and methylxanthine levels using HPLC. There was considerable variation between brands of high cocoa solid content, and epicatechin (EC) levels did not correlate with calculated % non-fat cocoa solids. EC-rich DC also had considerably high methylxanthine levels. EC-rich DC was used to assess acute endothelial fitness. EndoPAT index (PAT) was determined in fingertips (3 subjects). PAT was not affected by dark chocolate ingestion, but systolic blood pressure (SBP) increased significantly by 5.2±4.9 mmHg (p<O.04). In a further intervention study (3 subjects), no correlation was observed between flow-mediated dilation (FMD) and PAT before or after DC ingestion. Neither FMD nor PAT were affected by acute DC intake while SBP increased (+10.2±8.6 mmHg, p=O.058). Augmentation index (Alx) and• pulse wave velocity (PWV) remained constant. Acute FMD improved significantly by 2.8±2.0% (p<O.02) after intake of GT in another intervention study (6 subjects). DC, or DC and GT co-ingested, had no effect on FMD. SBP (+3.9±4.1 mmHg, p<O.05) and diastolic BP (DBP) (+4.1 ±2.9 mmHg, p<O.02) increased significantly after DC intake but not after GT, or DC and GT combined. Alx, PWV and area-under-the-shear-rate- curve remained unaffected by either dietary intervention. 5-hour urine specimen displayed higher concentrations of EC, 3'-O-methyl- EC and 4'-O-methyl-EC following intake of DC than GT, or DC and GT combined. No correlation was present between urinary flavanol metabolites and endothelial fitness markers. The presence of flavanols in the test foods may have been the underlying cause for FMD improvement following GT ingestion. After DC consumption, the beneficial effects of EC may have been counteracted by the pressor effects of the methylxanthines, which consistently led to BP increases in all 3 studies after DC ingestion.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:589024 |
| Date | January 2012 |
| Creators | Langer, Swen |
| Publisher | University of Leeds |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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