Dietetics, Nutrition and Biological Sciences
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Item The effect of green-coffee-bean extract rich in chlorogenic acid on antioxidant status of healthy human volunteers(Cambridge University Press, 2010-01) Almoosawi, Suzana; Tsang, Catherine; Davidson, Isobel M; Fyfe, LornaSeveral studies have linked consumption of green-coffee-bean extract (GCBE) rich in chlorogenic acid (CGA) with reduced blood pressure(Reference Watanabe, Arai and Mitsui1–Reference Ochiai, Jokura and Suzuki3). It is hypothesised that increased antioxidant activity could be one of the underlying mechanisms by which GCBE reduces blood pressure. To test this hypothesis a GCBE preparation rich in CGA was assessed by three extraction methods for antioxidant activity. In vivo antioxidant activity was also determined in a group of healthy volunteers. The phenolic content of GCBE, as determined by the Folin-Ciocalteu method, varied greatly between the ethanolic acidified water (0.2% (v/v) formic acid) and acetonitrile extract (acetonitrile–water containing 0.2% (v/v) formic acid; 50:50, v/v): 123 (sd 0.23), 131 (sd 0.66) and 211 (sd 0.51) mg gallic acid equivalents (GAE)/g extract respectively. Similar findings were observed with the Fe3+-reducing ability of plasma (FRAP) assay, wherein the acetonitrile extract exhibited a stronger Fe3+-reducing ability than the ethanolic extract (0.067 mmol/g extract v. 0.048 mmol/g extract). The 2,2-di(4-tert-octylphenyl)-1-picrylhydrazyl (DPPH) radical-scavenging activity of the ethanolic extract of GCBE was 70.4% at 50 μm as compared with ascorbic acid (86.1% inhibition at 50 μm) and GAE (82.2% at 50 μm). To examine in vivo antioxidant properties of GCBE thirteen healthy volunteers (age 36 (sd 11) years, BMI 28 (sd 2.5) kg/m2) consumed 200 mg GCBE containing 90 mg CGA twice daily for 2 weeks. In vivo antioxidant activity was determined using the Folin-Ciocalteu method and FRAP. There was a significant correlation between urinary polyphenols excretion as determined by the Folin-Ciocalteu method and FRAP (0.664, P<0.0001). However no significant increase in urinary antioxidant activity was observed (total phenolics: 173.2 (sd 137.8) mg GAE/g creatinine v. 175.20 (sd 115.7) mg GAE/g creatinine, P>0.05; FRAP: 2.07 (sd 0.9) mmol Fe2+/g creatinine v. 1.56 (sd 0.7) mmol Fe2+/g creatinine, P>0.05). Systolic blood pressure decreased from 119 (sd 10.5) to 114 (sd 9.1) mmHg (P=0.05) following the 2-week treatment. In conclusion, green coffee bean extract has a high antioxidant activity. However, no changes in antioxidant activity are observed in urine. This finding is consistent with previous findings of poor antioxidant activity of hippuric acid, the main urinary metabolite of chlorogenic acid(Reference Olthof, Hollman and Buijsman4). Further research is required to identify the mechanism(s) of reduction in blood pressure. The antioxidant activity of plasma should also be determined.Item Bioavailability and Urinary Excretion of Phenolic-Derived Metabolites after Acute Consumption of Purple Majesty Potato in Humans(E-Cronicon, 2015-03-18) Tsang, Catherine; Smail, Nacer F.; McDougall, Gordon J.; Almoosawi, Suzana; Al-Dujaili, Emad A. S.A novel purple potato variety, Purple Majesty (PM) contains an abundance of phenolic compounds, especially anthocyanins. The aim of this study was to assess the bioavailability of phenolic compounds in plasma measured as total polyphenols and urinary excretion of phenolic-derived metabolites after acute consumption of cooked PM. Five healthy male subjects (27-60 years; mean BMI: 26.7 ± 4.1) participated in a bioavailability study. Blood and urine were sampled at baseline and following consumption of 400 g cooked PM at 1h, 2h, 4h and 24h. A peak plasma antioxidant capacity was reached 1-2 hours post-consumption (from 1044 ± 281 µmol/L Fe(II) at baseline and increased to 1257 ± 180 after 1 hour (p = 0.045) and 1112 ± 251 µmol/L Fe(II) after 2 hours (borderline significance of p = 0.06). Total phenols level in plasma was reached after 2 hours (from 342.4 ± 28.3 at baseline to 368.4 ± 25 mg/L GAE). Liquid chromatography mass spectrometric (LC-MS) analysis was used to track the levels of anthocyanin-like derivatives and metabolites in the urine of volunteers after intake of the cooked Purple Majesty potatoes. No anthocyanin derivatives were detected in urine by liquid chromatography mass spectrometry indicating levels were < 2 nM. The majority of peaks that increased after intake were putatively identified as sulphated phenolic metabolites. Phenolic glucuronides were identified but other peaks remain unidentified. Hippuric acid was identified as a major phenolic derivative. Hydroxy benzoic derivatives, characteristic of intake of anthocyanins, were not detected in urine, however metabolites expected from the B-ring of petunidin (i.e. methyl gallic acid) may have been obscured by other peaks. Some metabolites could have arisen through metabolism of chlorogenic acid, which is present at ~ equivalent amounts to anthocyanins in cooked PM. In conclusion, acute consumption of PM resulted in an increase in excretion of urinary phenolic-derived metabolites. Identifying these unknown phenolic derivatives warrants further investigation.Item Intake of polyphenol-rich pomegranate pure juice influences urinary glucocorticoids, blood pressure and homeostasis model assessment of insulin resistance in human volunteers(2012-08) Tsang, Catherine; Smail, Nacer Foudil; Almoosawi, Suzana; Davidson, Isobel; Al-Dujaili, Emad A. S.Pomegranate juice (PJ; also known as pomegreat pure juice) provides a rich and varied source of polyphenolic compounds that may offer cardioprotective, anti-atherogenic and antihypertensive effects. The aim of this study was to investigate the effect of PJ consumption on glucocorticoids levels, blood pressure (BP) and insulin resistance in volunteers at high CVD risk. Subjects (twelve males and sixteen females) participated in a randomised, placebo-controlled cross-over study (BMI: 2677 (sd 336) kg/m2; mean age: 504 (sd 61) years). Volunteers were assessed at baseline, and at weeks 2 and 4 for anthropometry, BP and pulse wave velocity. Cortisol and cortisone levels in urine and saliva were determined by specific ELISA methods, and the cortisol/cortisone ratio was calculated. Fasting blood samples were obtained to assess plasma lipids, glucose, insulin and insulin resistance (homeostasis model assessment of insulin resistance). Volunteers consumed 500 ml of PJ or 500 ml of a placebo drink containing a similar amount of energy. Cortisol urinary output was reduced but not significant. However, cortisol/cortisone ratios in urine (P = 0009) and saliva (P = 0024) were significantly decreased. Systolic BP decreased from 1364 (sd 63) to 1289 (sd 51) mmHg (P = 0034), and diastolic BP from 803 (sd 429) to 755 (sd 517) mmHg (P = 0031) after 4 weeks of fruit juice consumption. Pulse wave velocity decreased from 75 (sd 086) to 744 (sd 094) m/s (P = 0035). There was also a significant reduction in fasting plasma insulin from 936 (sd 58) to 753 (sd 412) mIU/l (P = 0025) and of homeostasis model assessment of insulin resistance (from 2216 (sd 143) to 182 (sd 112), P = 0028). No significant changes were seen in the placebo arm of the study. These results suggest that PJ consumption can alleviate key cardiovascular risk factors in overweight and obese subjects that might be due to a reduction in both systolic and diastolic BP, possibly through the inhibition of 11_-hydroxysteroid dehydrogenase type 1 enzyme activity as evidenced by the reduction in the cortisol/cortisone ratio. The reduction in insulin resistance might have therapeutic benefits for patients with non-insulin-dependent diabetes, obesity and the metabolic syndrome.Item Investigating the inhibitory activity of green coffee and cacao bean extracts on pancreatic lipase(Wiley Interscience, 2010-08-20) Almoosawi, Suzana; McDougall, G. J.; Fyfe, Lorna; Al-Dujaili, Emad A. S.The present study investigated the effects of green coffee bean extract and Theobroma cacao bean extract on pancreatic lipase activity in vitro. Green coffee bean extract produced a J-shaped dose-dependent inhibition of pancreatic lipase with the percentage inhibition of pancreatic lipase ranging from 11.8% to 61.5%. Similar concentrations of Theobroma cacao failed to produce any effect on pancreatic lipase. Non-linear regression analysis revealed that the concentration of green coffee bean extract required to elicit a 50% inhibition of pancreatic lipase activity (IC50) was approximately 43 _M. In conclusion, extracts of green coffee beans but not Theobroma cacao possess potent inhibitory activity against pancreatic lipase. 2010 The Authors. Journal compilation 2010 British Nutrition Foundation.Item The effect of polyphenol-rich dark chocolate on fasting capillary whole blood glucose, total cholesterol, blood pressure and glucocorticoids in healthy overweight and obese subjects(Cambridge University Press, 2009-10-13) Almoosawi, Suzana; Fyfe, Lorna; Ho, Clement; Al-Dujaili, Emad A. S.Numerous studies indicate that polyphenol-rich chocolate reduces fasting blood glucose, blood pressure (BP) and total cholesterol in healthy individuals and hypertensives with or without glucose intolerance. The aim of the present study was to investigate the effect of two doses of polyphenol-rich dark chocolate (DC) on fasting capillary whole blood glucose, total cholesterol and BP and to examine whether improvements in these parameters are associated with changes in adrenocorticoid excretion in overweight and obese individuals. The study used a randomised, single-blind, cross-over design where fourteen overweight and obese subjects were randomised to either take 20 g DC with 500 mg polyphenols then 20 g DC with 1000 mg polyphenols or vice-versa. Participants followed each diet for 2 weeks separated by a 1-week washout period. It was observed that the 500 mg polyphenol dose was equally effective in reducing fasting blood glucose levels, systolic BP (SBP) and diastolic BP (DBP) as the 1000 mg polyphenol dose suggesting that a saturation effect might occur with increasing dose of polyphenols. There was also a trend towards a reduction in urinary free cortisone levels with both groups although it did not reach statistical significance. No changes in anthropometrical measurements were seen. We suggest that more research is required to investigate the mechanism(s) by which polyphenol-rich foods influence health.Item Differential effect of polyphenol-rich dark chocolate on glucoregulatory and cardiovascular risk factors on healthy overweight and obese subjects: a randomized clinical trial(Royal Society of Chemistry, 2012-07) Almoosawi, Suzana; Tsang, Catherine; Ostertag, L. M.; Fyfe, Lorna; Al-Dujaili, Emad A. S.The association between excess cortisol and various parameters of metabolic syndrome including hypertension, insulin resistance and dyslipidaemia is increasingly recognised. The present single-blind randomised placebo-controlled cross-over study compared the effect of polyphenol-rich dark chocolate (DC) on biomarkers of glucose metabolism, lipid profile, and blood pressure (BP) in females with BMI 25 kg m-2 (n = 21) and females with BMI < 25 kg m-2 (n = 21). Volunteers consumed 20 g of DC containing 500 mg polyphenols or a placebo DC with negligible polyphenol-content daily for 4 weeks, separated by a 2-week washout period. Systolic BP and diastolic BP decreased after 4 weeks of polyphenol-rich DC. Placebo raised fasting insulin, homeostasis model assessment of insulin resistance (HOMA-IR) and salivary cortisol, an effect that was significantly different from polyphenol-rich DC which had a negligible effect on fasting insulin, HOMA-IR and salivary cortisol. Females with BMI 25 kg m-2 responded less favourably to placebo than lean females and consequently had higher fasting insulin and HOMA-IR, in addition to a lower quantitative sensitivity check index (QUICKI) after ingestion of placebo compared to polyphenol-rich DC. No significant changes in lipid profile were observed. This study provides evidence for the metabolic benefits of consuming polyphenol-rich dark chocolate while demonstrating the possibility of adverse effects occurring with polyphenol-poor chocolate placebo.Item Effects of green tea consumption on blood pressure, total cholesterol, body weight and fat in healthy volunteers(2009) Al-Dujaili, Emad A. S.; Bradley, Jon-Paul; Almoosawi, Suzana; Fyfe, LornaBackground: Hypertension, obesity and hyperlipidemia are key interlinked features of both metabolic syndrome and cardiovascular disease. Numerous studies have suggested that green tea may reduce blood pressure by activating endothelial nitric oxide synthase and reducing total cholesterol by disrupting the production of apo B and synthesis of chylomicrons and thus have cardio-protective effects. The aim of this pilot study was to investigate the effects of increasing the consumption of green tea-rich catechins on blood pressure (BP), total cholesterol and other body composition parameters in healthy volunteers living in Scotland. Methods: Following a 2 day green tea free period, participants (n=12; 9 females and 3 males) were asked to drink 4 cups of green tea (organic Mao Jian Green Tea from the Zhejiang region of China) for 14 days (~800 ml green tea infusion containing 600-800 mg total catechins). Fasting total plasma cholesterol, BP, weight, BMI and %body fat were measured at day 0 (baseline), day 7 and day 14. Results: Mean systolic BP was reduced significantly by 7.1 mmHg (P<0.0001) and mean diastolic BP reduced by 7.8 mmHg over 14 days (P<0.0001). Mean fasting total cholesterol was reduced significantly by 0.556 mmol/l (P<0.008), BMI by 0.34 kg/m2 (P<0.001), body weight by 0.96 kg (P<0.001) and body fat by 2.36% (P<0.005). Conclusion: Our results has shown that short term consumption of commercial green tea reduces systolic and diastolic BP, fasting total cholesterol, %body fat and body weight suggesting a role for green tea in decreasing established potential cardiovascular risk factors. This study also suggests that reductions may be more pronounced in the overweight population where a significant proportion are obese and have a high risk of cardiovascular disease. Green tea consumption is cost effective, accepted by patients and has no reported side effects.Item Effect of green coffee bean extract and chlorogenic acid consumption on 11_HSD activity in humans and mice(2009-03) Almoosawi, Suzana; Dickinson, A.; Fyfe, Lorna; Kenyon, C. J.; Al-Dujaili, Emad A. S.Increased 11_ hydroxysteroid dehydrogenase type 1 (11_HSD1) activity is implicated in the development of the metabolic syndrome. Identifying natural compounds that influence 11_HSD1 activity could lead to novel methods of treating obesity, cardiovascular disease and diabetes. In the present study, we tested the effect of green coffee bean extract (GCBE), rich in chlorogenic acid (CGA), in human volunteers and of CGA in mice on blood pressure (BP), lipid and glucose metabolism. Our hypothesis was that CGA would improve these parameters, by blocking the uptake of microsomal glucose-6-phosphate which in turn would limit the production of co-factor for 11_HSD1 reductase activity. With local Ethics Committee approval, 13 healthy overweight subjects were given GCBE containing 90 mg CGA twice daily for 2 weeks. Urinary 24 h free cortisol was reduced from 1.05230.45 to 0.7630.40 nmol/kg (P=0.07). Free cortisone excretion was reduced from 0.7120.38 to 0.4320.24 nmol/kg (P=0.007). Systolic BP decreased from 119.410.5 to 113.89.1 mmHg (P=0.05). Fasting plasma glucose (P=0.101), diastolic BP (P=0.114), free cortisol:cortisone ratio (P=0.216) and anthropometrical measurement were not affected. In vitro, 11_HSD1 activity (conversion of added cortisone to cortisol) in isolated mouse microsomes was inhibited dose-dependently by CGA. The effects of feeding diet containing 0.15% CGA for 17 days was tested in male C57BL6 mice. Adiposity was unaffected but liver (27.74.9 vs 15.52.2 mg/g, P<0.04) and plasma (1.240.18 vs 0.860.08 mg/ml, P<0.08) triglycerides tended to be reduced. Urinary 24 h cortisol excretion following IP injection of 20 mg/kg cortisone was 30.14.1 vs 24.25.3 nmol/kg (P<0.4) for control and CGA-treated mice. Peak plasma glucose levels in tolerance tests were earlier with CGA treatment although, over a 2 h period, glucose clearance was not affected.