Research Interests:
Research Interests: Organic Chemistry, Nutrition and Dietetics, Coffee, Biomarkers, British, and 18 moreFlavonoids, Animal Production, Humans, Polyphenols, Tea, Female, Male, Gallic acid, Middle Aged, Phenols, Biological markers, Food Sciences, Drinking, Polyphenol, Human Subjects, Cross Sectional Studies, Case Control Studies, and Phenolic Acid
Research Interests:
Grape seed extract provides a concentrated source of polyphenols, most of which are proanthocyanidins. Polymeric proanthocyanidins are poorly absorbed in the small intestine of humans, and exposure may result from metabolism to phenolic... more
Grape seed extract provides a concentrated source of polyphenols, most of which are proanthocyanidins. Polymeric proanthocyanidins are poorly absorbed in the small intestine of humans, and exposure may result from metabolism to phenolic acids by colonic bacteria. Any biological effects of proanthocyanidins may be due to the phenolic acid metabolites. Several phenolic acids have been identified as proanthocyanidin metabolites, but these may be derived from a range of other dietary sources. The aim of this study was to determine if 24-h urinary excretion of specific phenolic acids increased significantly and consistently following regular supplementation with grape seed extract. In a randomized, double-blind placebo-controlled trial, 69 volunteers received grape seed extract (1000 mg/day total polyphenols) or placebo for 6 weeks. Supplementation with grape seed polyphenols resulted in a consistent increase in the excretion of 3-hydroxyphenylpropionic acid (3-HPP, P < 0.001) and 4-O-methylgallic acid (P < 0.001) and a less consistent increase in the excretion of 3-hydroxyphenylacetic acid (P = 0.002). The observed increase in 3-HPP is in line with the suggestion that this compound is a major phenolic acid breakdown product of proanthocyanidin metabolism in vivo.
Research Interests:
Research Interests: Treatment Outcome, Oxidative Stress, Antioxidants, Humans, Hypertension, and 18 moreBlood Pressure, Female, Male, Heart rate, Vascular endothelium, Dietary Supplements, Vitamin E, Randomised Controlled Trial, Clinical Sciences, Western Australia, Middle Aged, Alpha-Tocopherol, Time Factors, Gamma-Tocopherol, Combination drug therapy, Type 2 Diabetes Mellitus, Vasodilation, and Brachial artery
Research Interests:
1Oxidative stress has been suggested to be involved in the pathogenesis of hypertension. This may be via a number of possible mechanisms, including quenching of the important vasodilator nitric oxide.2Animal studies have generally... more
1Oxidative stress has been suggested to be involved in the pathogenesis of hypertension. This may be via a number of possible mechanisms, including quenching of the important vasodilator nitric oxide.2Animal studies have generally supported the hypothesis that increased blood pressure is associated with increased oxidative stress. However, human studies have been inconsistent and may differ owing to the populations studied and the various methods used. Treatment with anti-oxidants has been suggested to lower oxidative stress and, therefore, blood pressure. However, to date, studies investigating single or combination supplements have failed to show any consistent benefit.3Overall, the evidence supporting the link between hypertension and oxidative stress remains inconclusive, with methodological and population differences possibly confounding results. Further studies investigating this relationship are warranted.Oxidative stress has been suggested to be involved in the pathogenesis of hypertension. This may be via a number of possible mechanisms, including quenching of the important vasodilator nitric oxide.Animal studies have generally supported the hypothesis that increased blood pressure is associated with increased oxidative stress. However, human studies have been inconsistent and may differ owing to the populations studied and the various methods used. Treatment with anti-oxidants has been suggested to lower oxidative stress and, therefore, blood pressure. However, to date, studies investigating single or combination supplements have failed to show any consistent benefit.Overall, the evidence supporting the link between hypertension and oxidative stress remains inconclusive, with methodological and population differences possibly confounding results. Further studies investigating this relationship are warranted.
Research Interests:
Aim/hypothesis: We assessed whether dietary supplementation with coenzyme Q10 improves endothelial function of the brachial artery in patients with Type II (non-insulin-dependent) diabetes mellitus and dyslipidaemia. Methods: A total of... more
Aim/hypothesis: We assessed whether dietary supplementation with coenzyme Q10 improves endothelial function of the brachial artery in patients with Type II (non-insulin-dependent) diabetes mellitus and dyslipidaemia. Methods: A total of 40 patients with Type II diabetes and dyslipidaemia were randomized to receive 200 mg of coenzyme Q10 or placebo orally for 12 weeks. Endothelium-dependent and independent function of the brachial artery was measured as flow-mediated dilatation and glyceryl-trinitrate-mediated dilatation, respectively. A computerized system was used to quantitate vessel diameter changes before and after intervention. Arterial function was compared with 18 non-diabetic subjects. Oxidative stress was assessed by measuring plasma F2-isoprostane concentrations, and plasma antioxidant status by oxygen radical absorbance capacity. Results: The diabetic patients had impaired flow-mediated dilation [3.8 % (SEM 0.5) vs 6.4 % (SEM 1.0), p = 0.016], but preserved glyceryl-trinitrate-mediated dilation, of the brachial artery compared with non-diabetic subjects. Flow-mediated dilation of the brachial artery increased by 1.6 % (SEM 0.3) with coenzyme Q10 and decreased by –0.4 % (SEM 0.5) with placebo (p = 0.005); there were no group differences in the changes in pre-stimulatory arterial diameter, post-ischaemic hyperaemia or glyceryl-trinitrate-mediated dilation response. Coenzyme Q10 treatment resulted in a threefold increase in plasma coenzyme Q10 (p < 0.001) but did not alter plasma F2-isoprostanes, oxygen radical absorbance capacity, lipid concentrations, glycaemic control or blood pressure. Conclusion/interpretation: Coenzyme Q10 supplementation improves endothelial function of conduit arteries of the peripheral circulation in dyslipidaemic patients with Type II diabetes. The mechanism could involve increased endothelial release and/or activity of nitric oxide due to improvement in vascular oxidative stress, an effect that might not be reflected by changes in plasma F2-isoprostane concentrations. [Diabetologia (2002) 45: 420–426]
Research Interests: Endocrinology, Nutrition, Treatment, Oxidative Stress, Antioxidants, and 26 moreHumans, Diabetes mellitus, Blood Pressure, Cholesterol, Nitric oxide, Female, Male, Vascular endothelium, Placebos, Endothelial dysfunction, Triglycerides, Clinical Sciences, Aged, Middle Aged, Endothelial Function, Adult, Public health systems and services research, Lipoproteins, Type II Diabetes, Type 2 Diabetes Mellitus, Vasodilation, Cross-Over Studies, Blood Flow Velocity, Coenzyme Q, Diabetes Care, and Brachial artery
Research Interests:
Research Interests:
Research Interests:
Research Interests: Humans, Hypertension, Blood Pressure, Nitric oxide, Female, and 14 moreMale, Vascular endothelium, Body Mass Index, Endothelial dysfunction, Clinical Sciences, Public health systems and services research, Multiple regression analysis, Fatty Acid, Circulation, Gas Chromatography/mass Spectrometry, Vascular Endothelial Function, Vasodilation, Systolic blood pressure, and Brachial artery
Research Interests:
Research Interests: Nutrition, Free Radicals, Flavonoids, Cardiovascular disease, Free Radical, and 22 moreHumans, Blood Pressure, Nitric oxide, Female, Male, Nitrates, Vascular endothelium, Fruit and vegetables, Oxidative stress and free radical biology and medicine, Middle Aged, Endothelial Function, Malus, Adult, Randomized Controlled Trial, Pulse Pressure, Cardiovascular Diseases, Vasodilation, Cross-Over Studies, Nitrites, Biochemistry and cell biology, Systolic blood pressure, and Brachial artery
Research Interests: Engineering, Clinical Trial, Humans, von Willebrand factor, Female, and 17 moreMale, American, Dietary Supplements, Platelet activation mechanism, Platelet function, High Pressure Liquid Chromatography, Middle Aged, Alpha-Tocopherol, Analysis of Variance, Gamma-Tocopherol, Red blood cell, Type 2 Diabetes Mellitus, Erythrocytes, Tocopherols, Enzyme Linked Immunosorbent Assay, Blood cells, and Isomerism
Research Interests:
Research Interests: Organic Chemistry, Nutrition and Dietetics, Coffee, Biomarkers, British, and 18 moreFlavonoids, Animal Production, Humans, Polyphenols, Tea, Female, Male, Gallic acid, Middle Aged, Phenols, Biological markers, Food Sciences, Drinking, Polyphenol, Human Subjects, Cross Sectional Studies, Case Control Studies, and Phenolic Acid
Research Interests: Oxidative Stress, Flavonoids, Antioxidants, Humans, Polyphenols, and 17 moreHypertension, vitamin C, Blood Pressure, Female, Male, Vascular endothelium, Randomised Controlled Trial, Clinical Sciences, Middle Aged, Phenols, Ascorbic Acid, Randomized Controlled Trial, Biological markers, Combination drug therapy, Vasodilation, Tocopherols, and Brachial artery
Research Interests:
Research Interests: Humans, Hypertension, Blood Pressure, Nitric oxide, Female, and 14 moreMale, Vascular endothelium, Body Mass Index, Endothelial dysfunction, Clinical Sciences, Public health systems and services research, Multiple regression analysis, Fatty Acid, Circulation, Gas Chromatography/mass Spectrometry, Vascular Endothelial Function, Vasodilation, Systolic blood pressure, and Brachial artery
Research Interests:
Grape seed extract provides a concentrated source of polyphenols, most of which are proanthocyanidins. Polymeric proanthocyanidins are poorly absorbed in the small intestine of humans, and exposure may result from metabolism to phenolic... more
Grape seed extract provides a concentrated source of polyphenols, most of which are proanthocyanidins. Polymeric proanthocyanidins are poorly absorbed in the small intestine of humans, and exposure may result from metabolism to phenolic acids by colonic bacteria. Any biological effects of proanthocyanidins may be due to the phenolic acid metabolites. Several phenolic acids have been identified as proanthocyanidin metabolites, but these may be derived from a range of other dietary sources. The aim of this study was to determine if 24-h urinary excretion of specific phenolic acids increased significantly and consistently following regular supplementation with grape seed extract. In a randomized, double-blind placebo-controlled trial, 69 volunteers received grape seed extract (1000 mg/day total polyphenols) or placebo for 6 weeks. Supplementation with grape seed polyphenols resulted in a consistent increase in the excretion of 3-hydroxyphenylpropionic acid (3-HPP, P < 0.001) and 4-O-methylgallic acid (P < 0.001) and a less consistent increase in the excretion of 3-hydroxyphenylacetic acid (P = 0.002). The observed increase in 3-HPP is in line with the suggestion that this compound is a major phenolic acid breakdown product of proanthocyanidin metabolism in vivo.
Research Interests:
Research Interests:
Research Interests: Treatment Outcome, Oxidative Stress, Antioxidants, Humans, Hypertension, and 18 moreBlood Pressure, Female, Male, Heart rate, Vascular endothelium, Dietary Supplements, Vitamin E, Randomised Controlled Trial, Clinical Sciences, Western Australia, Middle Aged, Alpha-Tocopherol, Time Factors, Gamma-Tocopherol, Combination drug therapy, Type 2 Diabetes Mellitus, Vasodilation, and Brachial artery
Research Interests:
Research Interests:
1Oxidative stress has been suggested to be involved in the pathogenesis of hypertension. This may be via a number of possible mechanisms, including quenching of the important vasodilator nitric oxide.2Animal studies have generally... more
1Oxidative stress has been suggested to be involved in the pathogenesis of hypertension. This may be via a number of possible mechanisms, including quenching of the important vasodilator nitric oxide.2Animal studies have generally supported the hypothesis that increased blood pressure is associated with increased oxidative stress. However, human studies have been inconsistent and may differ owing to the populations studied and the various methods used. Treatment with anti-oxidants has been suggested to lower oxidative stress and, therefore, blood pressure. However, to date, studies investigating single or combination supplements have failed to show any consistent benefit.3Overall, the evidence supporting the link between hypertension and oxidative stress remains inconclusive, with methodological and population differences possibly confounding results. Further studies investigating this relationship are warranted.Oxidative stress has been suggested to be involved in the pathogenesis of hypertension. This may be via a number of possible mechanisms, including quenching of the important vasodilator nitric oxide.Animal studies have generally supported the hypothesis that increased blood pressure is associated with increased oxidative stress. However, human studies have been inconsistent and may differ owing to the populations studied and the various methods used. Treatment with anti-oxidants has been suggested to lower oxidative stress and, therefore, blood pressure. However, to date, studies investigating single or combination supplements have failed to show any consistent benefit.Overall, the evidence supporting the link between hypertension and oxidative stress remains inconclusive, with methodological and population differences possibly confounding results. Further studies investigating this relationship are warranted.
Research Interests:
Aim/hypothesis: We assessed whether dietary supplementation with coenzyme Q10 improves endothelial function of the brachial artery in patients with Type II (non-insulin-dependent) diabetes mellitus and dyslipidaemia. Methods: A total of... more
Aim/hypothesis: We assessed whether dietary supplementation with coenzyme Q10 improves endothelial function of the brachial artery in patients with Type II (non-insulin-dependent) diabetes mellitus and dyslipidaemia. Methods: A total of 40 patients with Type II diabetes and dyslipidaemia were randomized to receive 200 mg of coenzyme Q10 or placebo orally for 12 weeks. Endothelium-dependent and independent function of the brachial artery was measured as flow-mediated dilatation and glyceryl-trinitrate-mediated dilatation, respectively. A computerized system was used to quantitate vessel diameter changes before and after intervention. Arterial function was compared with 18 non-diabetic subjects. Oxidative stress was assessed by measuring plasma F2-isoprostane concentrations, and plasma antioxidant status by oxygen radical absorbance capacity. Results: The diabetic patients had impaired flow-mediated dilation [3.8 % (SEM 0.5) vs 6.4 % (SEM 1.0), p = 0.016], but preserved glyceryl-trinitrate-mediated dilation, of the brachial artery compared with non-diabetic subjects. Flow-mediated dilation of the brachial artery increased by 1.6 % (SEM 0.3) with coenzyme Q10 and decreased by –0.4 % (SEM 0.5) with placebo (p = 0.005); there were no group differences in the changes in pre-stimulatory arterial diameter, post-ischaemic hyperaemia or glyceryl-trinitrate-mediated dilation response. Coenzyme Q10 treatment resulted in a threefold increase in plasma coenzyme Q10 (p < 0.001) but did not alter plasma F2-isoprostanes, oxygen radical absorbance capacity, lipid concentrations, glycaemic control or blood pressure. Conclusion/interpretation: Coenzyme Q10 supplementation improves endothelial function of conduit arteries of the peripheral circulation in dyslipidaemic patients with Type II diabetes. The mechanism could involve increased endothelial release and/or activity of nitric oxide due to improvement in vascular oxidative stress, an effect that might not be reflected by changes in plasma F2-isoprostane concentrations. [Diabetologia (2002) 45: 420–426]
Research Interests: Endocrinology, Nutrition, Treatment, Oxidative Stress, Antioxidants, and 26 moreHumans, Diabetes mellitus, Blood Pressure, Cholesterol, Nitric oxide, Female, Male, Vascular endothelium, Placebos, Endothelial dysfunction, Triglycerides, Clinical Sciences, Aged, Middle Aged, Endothelial Function, Adult, Public health systems and services research, Lipoproteins, Type II Diabetes, Type 2 Diabetes Mellitus, Vasodilation, Cross-Over Studies, Blood Flow Velocity, Coenzyme Q, Diabetes Care, and Brachial artery
Research Interests:
Research Interests:
Research Interests:
Research Interests: Humans, Hypertension, Blood Pressure, Nitric oxide, Female, and 14 moreMale, Vascular endothelium, Body Mass Index, Endothelial dysfunction, Clinical Sciences, Public health systems and services research, Multiple regression analysis, Fatty Acid, Circulation, Gas Chromatography/mass Spectrometry, Vascular Endothelial Function, Vasodilation, Systolic blood pressure, and Brachial artery
Research Interests:
Research Interests: Nutrition, Free Radicals, Flavonoids, Cardiovascular disease, Free Radical, and 22 moreHumans, Blood Pressure, Nitric oxide, Female, Male, Nitrates, Vascular endothelium, Fruit and vegetables, Oxidative stress and free radical biology and medicine, Middle Aged, Endothelial Function, Malus, Adult, Randomized Controlled Trial, Pulse Pressure, Cardiovascular Diseases, Vasodilation, Cross-Over Studies, Nitrites, Biochemistry and cell biology, Systolic blood pressure, and Brachial artery
Research Interests: Engineering, Clinical Trial, Humans, von Willebrand factor, Female, and 17 moreMale, American, Dietary Supplements, Platelet activation mechanism, Platelet function, High Pressure Liquid Chromatography, Middle Aged, Alpha-Tocopherol, Analysis of Variance, Gamma-Tocopherol, Red blood cell, Type 2 Diabetes Mellitus, Erythrocytes, Tocopherols, Enzyme Linked Immunosorbent Assay, Blood cells, and Isomerism
Research Interests: Oxidative Stress, Flavonoids, Antioxidants, Humans, Polyphenols, and 17 moreHypertension, vitamin C, Blood Pressure, Female, Male, Vascular endothelium, Randomised Controlled Trial, Clinical Sciences, Middle Aged, Phenols, Ascorbic Acid, Randomized Controlled Trial, Biological markers, Combination drug therapy, Vasodilation, Tocopherols, and Brachial artery
Research Interests: Humans, Hypertension, Blood Pressure, Nitric oxide, Female, and 14 moreMale, Vascular endothelium, Body Mass Index, Endothelial dysfunction, Clinical Sciences, Public health systems and services research, Multiple regression analysis, Fatty Acid, Circulation, Gas Chromatography/mass Spectrometry, Vascular Endothelial Function, Vasodilation, Systolic blood pressure, and Brachial artery
Research Interests:
Research Interests:
Research Interests: Organic Chemistry, Nutrition and Dietetics, Coffee, Biomarkers, British, and 18 moreFlavonoids, Animal Production, Humans, Polyphenols, Tea, Female, Male, Gallic acid, Middle Aged, Phenols, Biological markers, Food Sciences, Drinking, Polyphenol, Human Subjects, Cross Sectional Studies, Case Control Studies, and Phenolic Acid
Research Interests:
Research Interests:
Research Interests:
Grape seed extract provides a concentrated source of polyphenols, most of which are proanthocyanidins. Polymeric proanthocyanidins are poorly absorbed in the small intestine of humans, and exposure may result from metabolism to phenolic... more
Grape seed extract provides a concentrated source of polyphenols, most of which are proanthocyanidins. Polymeric proanthocyanidins are poorly absorbed in the small intestine of humans, and exposure may result from metabolism to phenolic acids by colonic bacteria. Any biological effects of proanthocyanidins may be due to the phenolic acid metabolites. Several phenolic acids have been identified as proanthocyanidin metabolites, but these may be derived from a range of other dietary sources. The aim of this study was to determine if 24-h urinary excretion of specific phenolic acids increased significantly and consistently following regular supplementation with grape seed extract. In a randomized, double-blind placebo-controlled trial, 69 volunteers received grape seed extract (1000 mg/day total polyphenols) or placebo for 6 weeks. Supplementation with grape seed polyphenols resulted in a consistent increase in the excretion of 3-hydroxyphenylpropionic acid (3-HPP, P < 0.001) and 4-O-methylgallic acid (P < 0.001) and a less consistent increase in the excretion of 3-hydroxyphenylacetic acid (P = 0.002). The observed increase in 3-HPP is in line with the suggestion that this compound is a major phenolic acid breakdown product of proanthocyanidin metabolism in vivo.
Research Interests:
Research Interests: Treatment Outcome, Oxidative Stress, Antioxidants, Humans, Hypertension, and 18 moreBlood Pressure, Female, Male, Heart rate, Vascular endothelium, Dietary Supplements, Vitamin E, Randomised Controlled Trial, Clinical Sciences, Western Australia, Middle Aged, Alpha-Tocopherol, Time Factors, Gamma-Tocopherol, Combination drug therapy, Type 2 Diabetes Mellitus, Vasodilation, and Brachial artery
Research Interests:
1Oxidative stress has been suggested to be involved in the pathogenesis of hypertension. This may be via a number of possible mechanisms, including quenching of the important vasodilator nitric oxide.2Animal studies have generally... more
1Oxidative stress has been suggested to be involved in the pathogenesis of hypertension. This may be via a number of possible mechanisms, including quenching of the important vasodilator nitric oxide.2Animal studies have generally supported the hypothesis that increased blood pressure is associated with increased oxidative stress. However, human studies have been inconsistent and may differ owing to the populations studied and the various methods used. Treatment with anti-oxidants has been suggested to lower oxidative stress and, therefore, blood pressure. However, to date, studies investigating single or combination supplements have failed to show any consistent benefit.3Overall, the evidence supporting the link between hypertension and oxidative stress remains inconclusive, with methodological and population differences possibly confounding results. Further studies investigating this relationship are warranted.Oxidative stress has been suggested to be involved in the pathogenesis of hypertension. This may be via a number of possible mechanisms, including quenching of the important vasodilator nitric oxide.Animal studies have generally supported the hypothesis that increased blood pressure is associated with increased oxidative stress. However, human studies have been inconsistent and may differ owing to the populations studied and the various methods used. Treatment with anti-oxidants has been suggested to lower oxidative stress and, therefore, blood pressure. However, to date, studies investigating single or combination supplements have failed to show any consistent benefit.Overall, the evidence supporting the link between hypertension and oxidative stress remains inconclusive, with methodological and population differences possibly confounding results. Further studies investigating this relationship are warranted.
Research Interests:
Aim/hypothesis: We assessed whether dietary supplementation with coenzyme Q10 improves endothelial function of the brachial artery in patients with Type II (non-insulin-dependent) diabetes mellitus and dyslipidaemia. Methods: A total of... more
Aim/hypothesis: We assessed whether dietary supplementation with coenzyme Q10 improves endothelial function of the brachial artery in patients with Type II (non-insulin-dependent) diabetes mellitus and dyslipidaemia. Methods: A total of 40 patients with Type II diabetes and dyslipidaemia were randomized to receive 200 mg of coenzyme Q10 or placebo orally for 12 weeks. Endothelium-dependent and independent function of the brachial artery was measured as flow-mediated dilatation and glyceryl-trinitrate-mediated dilatation, respectively. A computerized system was used to quantitate vessel diameter changes before and after intervention. Arterial function was compared with 18 non-diabetic subjects. Oxidative stress was assessed by measuring plasma F2-isoprostane concentrations, and plasma antioxidant status by oxygen radical absorbance capacity. Results: The diabetic patients had impaired flow-mediated dilation [3.8 % (SEM 0.5) vs 6.4 % (SEM 1.0), p = 0.016], but preserved glyceryl-trinitrate-mediated dilation, of the brachial artery compared with non-diabetic subjects. Flow-mediated dilation of the brachial artery increased by 1.6 % (SEM 0.3) with coenzyme Q10 and decreased by –0.4 % (SEM 0.5) with placebo (p = 0.005); there were no group differences in the changes in pre-stimulatory arterial diameter, post-ischaemic hyperaemia or glyceryl-trinitrate-mediated dilation response. Coenzyme Q10 treatment resulted in a threefold increase in plasma coenzyme Q10 (p < 0.001) but did not alter plasma F2-isoprostanes, oxygen radical absorbance capacity, lipid concentrations, glycaemic control or blood pressure. Conclusion/interpretation: Coenzyme Q10 supplementation improves endothelial function of conduit arteries of the peripheral circulation in dyslipidaemic patients with Type II diabetes. The mechanism could involve increased endothelial release and/or activity of nitric oxide due to improvement in vascular oxidative stress, an effect that might not be reflected by changes in plasma F2-isoprostane concentrations. [Diabetologia (2002) 45: 420–426]