Low-polyphenol Diet Research Articles

Catechin-Rich Green Tea Extract Reduced Intestinal Inflammation and Fasting Glucose in Metabolic Syndrome and Healthy Adults: A Randomized, Controlled, Crossover Trial

Abstract Objectives Preclinical evidence demonstrated that catechin-rich green tea extract (GTE) improves gut barrier function and reduces intestinal and systemic inflammation. Thus, this clinical trial was conducted to test the hypothesis that GTE would alleviate intestinal inflammation relative to cardiometabolic risk in persons with metabolic syndrome (MetS). Methods We conducted a randomized, double-blind, placebo-controlled, crossover trial in adults with MetS and age- and gender-matched healthy persons who received confections without (placebo) or with 1 g/d GTE (890 mg catechins) for 28 d while following a low-polyphenol diet. Dietary polyphenols, fasting blood glucose, insulin, and lipids were assessed at d 0, 14, and 28 of each intervention. Intestinal inflammation was assessed by measuring neutrophil-derived calprotectin and myeloperoxidase by ELISA in pooled stool samples collected over the last 3 d of each intervention. Data were analyzed using RM ANOVA and multiple linear regression. Results MetS (n = 21; 40 ± 3 y; 35 ± 1 kg/m2) and healthy (n = 19; 34 ± 2 y; 22 ± 0.4 kg/m2) persons completed the study with high compliance (>95%), no adverse effects, or changes in body mass. Participants’ total polyphenol intakes decreased during each intervention compared with baseline (P < 0.001). Fecal calprotectin and myeloperoxidase were lower (P < 0.05) in GTE compared with placebo regardless of health status. Although fasting insulin, triglycerides, total and high-density lipoprotein cholesterol were unaffected by treatment, fasting glucose decreased (P < 0.01) in response to GTE regardless of health status. Age (β = −0.29; P = 0.05) and between-trial changes in myeloperoxidase (β = 0.03; P < 0.04) were predictive of changes in insulin after controlling for sex, waist circumference, and changes in blood lipids and calprotectin. Conclusions Dietary intervention with GTE-rich confections in weight-stable healthy and MetS adults decreased fasting glucose and intestinal inflammation, which was associated with improvements in fasting insulin. This suggests that gut-level anti-inflammatory activities of GTE may improve glycemic control with reductions in intestinal inflammation contributing to enhance insulin sensitivity. Funding Sources USDA-NIFA, USDA-HATCH, and the Ohio Agricultural Research and Development Center at the Ohio State University.

A Green Tea Extract-Rich Confection in Healthy and Metabolic Syndrome Adults Decreases Small Intestinal Permeability in Association With Lower Gut Inflammation

ObjectivesPoor gut health, including increased intestinal permeability and inflammation, enhances cardiometabolic risk. Catechin-rich green tea extract (GTE) alleviates cardiometabolic complications in obese rodents by limiting gut permeability and inflammation, but whether these benefits occur in humans is not known. We hypothesized that the anti-inflammatory activities of GTE would decrease gut barrier dysfunction in persons at heightened cardiometabolic risk. MethodsIn a randomized, double-blind, placebo-controlled crossover study, persons with metabolic syndrome (MetS) and healthy persons completed two 4-wk interventions in which they received placebo or GTE confections (890 mg/d total catechins) while following a low-polyphenol diet. At wk 4, participants provided fecal samples for ELISA-based measures of inflammatory proteins. 24-h urine samples were also collected for LC/MS analysis of non-digestible sugars following the ingestion of lactulose (LAC), mannitol (MAN), sucralose (SUC), and erythritol (ERY). Data were analyzed by repeated measures ANOVA and linear regression controlling for within-subject repeated measures. ResultsMetS (n = 21; 40 ± 3 y; 35.2 ± 1.0 kg/m2) and healthy (n = 19; 34 ± 2 y; BMI = 22.3 ± 0.4 kg/m2) adults completed the study with no adverse effects, no changes in liver function tests, and > 95% compliance based on returned confections. Urinary SUC/ERY was unaffected by GTE and health status, but urinary LAC/MAN was lower (P = 0.043) in GTE compared with placebo regardless of health status. Fecal myeloperoxidase and calprotectin did not differ by health status, but were lower (P = 0.03–0.05) in response to GTE regardless of health status, and were positively correlated with each other (r = 0.75; P < 0.001). Fecal calprotectin and myeloperoxidase were both positively correlated with LAC/MAN ratio (r = 0.39–0.42; P = 0.01–0.02). ConclusionsInterim findings of this study support that dietary GTE decreases small intestinal permeability in association with lower gut inflammation, which may help to explain its known cardiometabolic benefits. Funding SourcesUSDA-NIFA (2019–67,017-29,259), USDA-HATCH, and the Ohio Agricultural Research and Development Center at The Ohio State University.

Epigallocatechin Is Eliminated Faster From Plasma Than Epigallocatechin Gallate: Mathematical Modeling of Green Tea Catechin Metabolism in Healthy Adults

Abstract Objectives The predominant catechins [epigallocatechin gallate (EGCG), epigallocatechin (EGC), epicatechin (EC), epicatechin gallate (ECG)] in green tea extract (GTE) vary in bioactivity. Our objective was to develop a physiologically relevant mathematical model of catechin metabolism and assess their fractional catabolic rates relative to their structural attributes, which may influence their bioactivities. Methods Pharmacokinetic data were collected from healthy adults (n = 18; 27 ± 7 y; 22 ± 2 kg/m2) after oral intake of 0.5 g GTE (EGCG: 290 mg, EGC: 87 mg, EC: 39 mg, ECG: 28 mg) delivered in 3 gelatin-based confections. Participants maintained a low-polyphenol diet for 3 d prior to the trial. Concentrations of deconjugated catechins were measured by LC-MS in plasma and urine collected at timed intervals over 12 and 24 h, respectively. A multi-compartment model of catechin metabolism was developed using the mean fraction of dose for all catechins. Data were fitted by iterative least squares regression analysis in WinSAAM software. Kinetic parameters for EGCG and EGC were compared using a Student t-test and one-way ANOVA. Results Observed data for each catechin were successfully fit into a 7-compartment model comprised of the gastrointestinal tract (stomach, small and large intestine), liver, plasma, extravascular tissues, and kidneys. Goodness of fit was ascertained by the estimated variability of parameters (FSD &amp;lt; 0.5). Based on plasma response profiles, EGC and EC disappeared from plasma faster compared with EGCG and ECG. The highest fractional uptake was by the extravascular tissues (P &amp;lt; 0.05) with no other between-organ differences. Compared with EGCG, EGC showed a higher fractional transfer from the liver to plasma (2.5 vs. 0.4 pools/h, P &amp;lt; 0.001) and the uptake by kidneys (1.2 vs. 0.01 pools/h, P &amp;lt; 0.001) with no difference in absorption. The fractional catabolic rate was also higher for EGC compared with EGCG (59.4 vs. 42.7 plasma pools/h, P &amp;lt; 0.05), while its plasma transit time was shorter (0.9 vs. 1.3 min, P &amp;lt; 0.05). Conclusions A 7-compartment model, to be validated in a future study, was successfully developed to demonstrate that EGC is eliminated faster compared with EGCG in healthy adults, suggesting that the gallate group may influence relative bioactivity of catechins. Funding Sources The Ohio State University and the National Institute of Food and Agriculture.

A High Polyphenol Diet Improves Psychological Well-Being: The Polyphenol Intervention Trial (PPhIT).

Mental ill health is currently one of the leading causes of disease burden worldwide. A growing body of data has emerged supporting the role of diet, especially polyphenols, which have anxiolytic and antidepressant-like properties. The aim of the present study was to assess the effect of a high polyphenol diet (HPD) compared to a low polyphenol diet (LPD) on aspects of psychological well-being in the Polyphenol Intervention Trial (PPhIT). Ninety-nine mildly hypertensive participants aged 40–65 years were enrolled in a four-week LPD washout period and then randomised to either an LPD or an HPD for eight weeks. Both at baseline and the end of intervention, participants’ lifestyle and psychological well-being were assessed. The participants in the HPD group reported a decrease in depressive symptoms, as assessed by the Beck Depression Inventory-II, and an improvement in physical component and mental health component scores as assessed with 36-Item Short Form Survey. No differences in anxiety, stress, self-esteem or body image perception were observed. In summary, the study findings suggest that the adoption of a polyphenol-rich diet could potentially lead to beneficial effects including a reduction in depressive symptoms and improvements in general mental health status and physical health in hypertensive participants.

Addition of chocolate milk to diet corresponds to protein concentration changes in human saliva

Salivary proteins have the potential to alter oral sensory perception of foods. In rodents, dietary polyphenol exposure increases salivary concentrations of polyphenol-binding proteins and several cystatins, which correlate with less aversion to polyphenol-rich solutions. If similar salivary shifts occur in humans, then increasing dietary polyphenols may improve orosensory experience of polyphenol-rich foods. We hypothesized that small dietary changes, focused on polyphenols, would increase expression of salivary binding proteins for polyphenols and thus suppress unpleasant polyphenol sensations. However, analogs of salivary polyphenol-binding proteins are found in foods. Thus, we also hypothesized that food-sourced analogs of these salivary proteins would mitigate changes in saliva and sensation. Human subjects (N=55) alternated weeks of consuming a low polyphenol diet and then a regular diet plus a polyphenol-rich chocolate milk (almond, containing no polyphenol-binding proteins, or bovine, containing polyphenol-binding proteins). Statistical analyses revealed both chocolate milk interventions corresponded to changes in relative expression of 96 proteins and calculated concentration of 146 proteins (both after correction for false discovery rate), out of 1,176 proteins identified through proteomics. Of the proteins that changed, proline-rich proteins and cystatins were noticeable, which reflects prior work in animal studies. Subjects rated all chocolate milks as less flavorful after the bovine chocolate milk intervention week compared to low polyphenol weeks, but generally sensory changes were minimal. However, the results confirm that dietary changes coincide with salivary changes, and that some of those changes occur in proteins that have potential to influence oral sensations.

A Pilot Comparative Pharmacokinetic Study on Mango Polyphenols After Acute Intake of Fresh and Individual Quick Frozen Mango Pulp in Healthy Human Subjects

Abstract Objectives The objective of this study was to characterize and compare the pharmacokinetic profile of polyphenolic metabolites after acute intake of fresh and individually quick frozen (IQF) mango pulp in human plasma over 24 hours. Methods Healthy human subjects (n = 7, age = 31 ± 3 years, BMI = 22.7 ± 0.6 kg/m2) received IQF or fresh mango pulp (500 g) or control (100 mg vitamin C) in random order after 3-day low polyphenol diet in a cross over study design. Polyphenols in mango pulps (fresh and IQF) and their metabolites were characterized in plasma collected before (fasting, baseline) and at 30 min or hourly intervals for 8 h then again at 24 h using ultra high performance liquid chromatography and mass spectrometry (UHPLC-MS). Multiple comparisons within and among treatments (IQF and Fresh) over 24 h postprandial time were performed by mixed model using SAS with statistical significance set at P &amp;lt; 0.05. Results Gallic acid (228.1 ± 7.3 µg/100 g fresh weight, FW) and galloyl glucose (5.0 ± 0.2 µg/100 FW) were significantly higher (P &amp;lt; 0.05) in fresh compared to IQF mango pulp. In plasma however, gallic acid (Cmax = 17.3 ± 4.0 nmol/L, AUC0–24h = 63.9 ± 7.9 nmol × h/L), galloyl glucose (Cmax = 12.4 ± 2.3 nmol/L, AUC0–24h = 49.2 ± 8.1 nmol × h/L), ferulic acid hexoside (Cmax = 2.8 ± 0.5 nmol/L, AUC0–24h = 8.6 ± 1.9 nmol × h/L), and gallic acid and pyrogallol metabolites (sulfates, methyl and glucuronides) were significantly higher after IQF mango pulp intake compared to fresh mango pulp as assessed by maximum concentrations achieved (Cmax) and area under the curve (AUC0–24 h). Conclusions These results indicate that IQF may preserve or enhance the bio-accessibility of mango (poly)phenol components compared to fresh mangoes, which are hot water treated before importing into the USA. Funding Sources This study was funded by the National Mango Board.

Intestinal-level anti-inflammatory bioactivities of catechin-rich green tea: Rationale, design, and methods of a double-blind, randomized, placebo-controlled crossover trial in metabolic syndrome and healthy adults

Metabolic endotoxemia initiates low-grade chronic inflammation in metabolic syndrome (MetS) and provokes the progression towards more advanced cardiometabolic disorders. Our recent works in obese rodent models demonstrate that catechin-rich green tea extract (GTE) improves gut barrier integrity to alleviate the translocation of gut-derived endotoxin and its consequent pro-inflammatory responses mediated through Toll-like receptor-4/nuclear factor κB (TLR4/NFκB) signaling. The objective of this clinical trial is to establish the efficacy of GTE to alleviate metabolic endotoxemia-associated inflammation in persons with MetS by improving gut barrier function. We plan a double-blind, placebo-controlled cross-over trial in persons with MetS and age- and gender-matched healthy persons (18–65 y; n = 20/group) who will receive a low-energy GTE-rich (1 g/day; 890 mg total catechins) confection snack food while following a low-polyphenol diet for 28 days. Assessments will include measures of circulating endotoxin (primary outcome) and secondary outcomes including biomarkers of endotoxin exposure, region-specific measures of intestinal permeability, gut microbiota composition, diversity, and functions, intestinal and systemic inflammatory responses, and catechins and microbiota-derived catechin metabolites. Study outcomes will provide the first report of the GTE-mediated benefits that alleviate gut barrier dysfunction in relation to endotoxemia-associated inflammation in MetS persons. This is expected to help establish an effective dietary strategy to mitigate the growing burden of MetS that currently affects ~35% of Americans.

Effects of a diet naturally rich in polyphenols on lipid composition of postprandial lipoproteins in high cardiometabolic risk individuals: an ancillary analysis of a randomized controlled trial.

Plasma lipoprotein composition, especially in the postprandial state, could be relevant for cardiovascular risk and could be influenced by eating habits. This study evaluated the effects of a polyphenol-rich diet on postprandial lipoprotein composition in individuals at high cardiometabolic risk. Seventy-eight individuals with high waist circumference and at least another component of the metabolic syndrome were randomized to either a high-polyphenol (HighP) or low-polyphenol (LowP) diet. Before and after the 8-week intervention, chylomicrons, VLDL1, VLDL2, IDL, LDL, HDL particles, and their lipid concentrations were determined over a 6-h high-fat test meal with high or low-polyphenol content, according to the diet assigned. VLDL1 postprandial areas under the curve (AUCs) were lower for cholesterol (Chol) (1.48 ± 0.98 vs. 1.91 ± 1.13 mmol/L × 6 h, M ± SD, p = 0.014) and triglycerides (Tg) (4.70 ± 2.70 vs. 6.02 ± 3.07 mmol/L × 6 h, p = 0.005) after the HighP than after the LowP diet, with no changes in Chol/Tg ratio. IDL Chol AUCs were higher after the HighP than after the LowP diet (1.29 ± 0.77 vs. 1.01 ± 0.51 mmol/L × 6 h, p = 0.037). LDL Tg AUCs were higher after the HighP than after the LowP diet (1.15 ± 0.33 vs. 1.02 ± 0.35 mmol/L × 6 h, p < 0.001), with a lower Chol/Tg ratio (14.6 ± 4.0 vs. 16.0 ± 3.8, p = 0.007). HDL Tg AUCs were lower after the HighP than after the LowP diet (1.20 ± 0.41 vs. 1.34 ± 0.37 mmol/L × 6 h, p = 0.013). A high-polyphenol diet reduces the postprandial lipid content of large VLDL and increases IDL cholesterol; it modifies the composition of LDL particles-which become richer in triglycerides, and of HDL-which become instead triglyceride poor. The overall changes in atherogenicity by these effects warrant further investigation on clinical cardiovascular outcomes.

Grape pomace polyphenols improve insulin response to a standard meal in healthy individuals: A pilot study

Dietary polyphenols have beneficial effects on glucose/lipid metabolism in subjects at high risk to develop type 2 diabetes; however, the underlying mechanisms are not clear. We aimed to evaluate: 1) the acute effects of the consumption of a drink rich in polyphenols from red grape pomace (RGPD) on glucose/insulin and triglyceride responses to a standard meal in healthy individuals, and, 2) the relationship between plasma levels of phenolic metabolites and metabolic parameters. Twelve healthy men, aged 20-40 years participated in a randomized, controlled study according to a cross-over design. After a 3-day low-polyphenol diet, all participants consumed, on two different days and separated by a one week interval, after an overnight fast, a drink rich in polyphenols (1.562g gallic acid equivalents (GAE)) or a control drink (CD, no polyphenols), followed after 3h by a standard meal (960kcal, 18% protein, 30% fat, 52% CHO). Blood samples were taken at fasting, 3h after the drink, over 5h after the standard meal and at fasting on the next day to measure plasma concentrations of glucose, insulin, triglyceride and phenolic metabolites. Glycemic and triglyceride post-meal responses were similar after both the RGPD and the control drink. In contrast, postprandial insulin incremental area (iAUC0-5h) was 31% lower (p<0.05), insulin secretion index was 18% lower (p<0.016) and insulin sensitivity (SI) index was 36% higher (p=0.037) after the RGPD compared to CD. Among phenolic metabolites, gallic acid correlated inversely with the insulin response (r=-0.604; p=0.032) and positively with the SI index (r=0.588, p=0.037). RGPD consumption acutely reduced postprandial insulin levels and improved insulin sensitivity. This effect could be likely related to the increase in gallic acid levels. This drink, added to usual diet, could contribute to increase the daily intake of polyphenols, with potential health benefits. CLINICALTRIALS. NCT02865278.

Changing to a Low-Polyphenol Diet Alters Vascular Biomarkers in Healthy Men after Only Two Weeks

Bioactive dietary compounds play a critical role in health maintenance. The relation between bioactive compound intake and cardiovascular health-related biomarkers has been demonstrated in several studies, although mainly with participants who have altered biochemical parameters (high blood pressure, high cholesterol, metabolic syndrome, etc.). The aim of this study was to evaluate if adopting a diet low in polyphenol-rich food for two weeks would affect vascular biomarkers in healthy men. In a crossover study, 22 healthy men were randomly assigned to their usual diet (UD), consuming healthy food rich in polyphenols, or to a low antioxidant diet (LAD), with less than two servings of fruit and vegetables per day and avoiding the intake of cocoa products, coffee and tea. As a marker of compliance, total polyphenols in urine were significantly lower after the LAD than after the UD (79 ± 43 vs. 123 ± 58 mg GAE/g creatinine). Nitric oxide levels were also reduced (52 ± 28 in LAD vs. 80 ± 34 µM in UD), although no significant changes in cellular adhesion molecules and eicosanoids were observed; however, an increasing ratio between thromboxane A2 (TXA2) and prostaglandin I2 (PGI2) was reached (p = 0.048). Thus, a slight dietary modification, reducing the consumption of polyphenol-rich food, may affect vascular biomarkers even in healthy individuals.

The urinary phenolic acid profile varies between younger and older adults after a polyphenol-rich meal despite limited differences in in vitro colonic catabolism

PurposeTo investigate whether age influences colonic polyphenol metabolism.MethodsHealthy participants, younger (n = 8; 23–43 years) and older (n = 13; 51–76 years), followed a 3-day low-polyphenol diet (LPD) and a 3-day high-polyphenol diet (HPD). Urinary phenolic acids (PA), short chain fatty acids (SCFA), pH and gas were monitored, alongside selected colonic bacteria. Human faecal in vitro fermentations of rutin with or without raftiline were used to evaluate the gut microbiota capacity in a subset of both groups.ResultsTotal urinary PA were higher in the older group after HPD compared to the younger group (1.5-fold; p = 0.04), with no difference between groups in terms of a change between diets (Δ high-low diet). While 17 PA were detected in all younger participants after HPD, a narrower range (n = 8 to 16 PA) was detected in most (n = 9/13) older participants, with lower level of benzoic acid (19-fold; p = 0.03), vanillic acid (4.5-fold; p = 0.04) but higher hippuric acid (2.7-fold; p = 0.03). Faecal SCFA concentration did not change after HPD within group, with similar differential excretion (Δ high-low diet) between groups. There were no differences between groups for faecal pH, total, faecal bacteria including Flavonifractor plautii, bifidobacteria, and bacteroides. In human in vitro faecal fermentations, seven PAs were detected in both groups after 24 h of rutin fermentation, with no quantitative and modest qualitative differences between groups. Total SCFA in faecal fermentation did not differ between groups, except for butyric acid (twofold higher in the older group; p = 0.009) when rutin was fermented with raftiline over 24 h.ConclusionsUrinary phenolic acids were less diverse in older participants despite limited difference in functional capacity of in vitro faecal fermentations.

Beneficial effect of a polyphenol-rich diet on cardiovascular risk: a randomised control trial

ObjectivesThere is previous epidemiological evidence that intake of polyphenol-rich foods has been associated with reduced cardiovascular disease risk. We aimed to investigate the effect of increasing dietary polyphenol intake on...

Oxidised LDL levels decreases after the consumption of ready-to-eat meals supplemented with cocoa extract within a hypocaloric diet

Background and aimsCocoa flavanols are recognised by their favourable antioxidant and vascular effects. This study investigates the influence on health of the daily consumption of ready-to-eat meals supplemented with cocoa extract within a hypocaloric diet, on middle-aged overweight/obese subjects. Methods and resultsFifty healthy male and female middle-aged volunteers [57.26 ± 5.24 years and body mass index (BMI) 30.59 ± 2.33 kg/m2] were recruited to participate in a 4 week randomised, parallel and double-blind study. After following 3 days on a low-polyphenol diet, 25 volunteers received meals supplemented with 1.4 g of cocoa extract (645.3 mg of polyphenols) and the other 25 participants received control meals, within a 15% energy restriction diet. On the 4th week of intervention individuals in both dietary groups improved (p < 0.05) anthropometric, body composition, blood pressure and blood biochemical measurements. Oxidised LDL cholesterol (oxLDL), showed a higher reduction (p = 0.030) in the cocoa group. Moreover, myeloperoxidase (MPO) levels decreased only in the cocoa supplemented group (p = 0.007). Intercellular Adhesion Molecule-1 (sICAM-1) decreased significantly in both groups, while Vascular Cell Adhesion Molecule-1 (sVCAM-1) did not present differences after the 4 weeks of intervention. Interestingly, cocoa intake showed a different effect by gender, presenting more beneficial effects in men. ConclusionsThe consumption of cocoa extract as part of ready-to-eat meals and within a hypocaloric diet improved oxidative status (oxLDL) in middle-aged subjects, being most remarkable in males.Registration number: Registered at www.clinicaltrials.gov (NCT01596309).

Absorption of dimethoxycinnamic acid derivatives in vitro and pharmacokinetic profile in human plasma following coffee consumption

This study reports the 24 h human plasma pharmacokinetics of 3,4-dimethoxycinnamic acid (dimethoxycinnamic acid) after consumption of coffee, and the membrane transport characteristics of certain dimethoxycinnamic acid derivatives, as present in coffee. Eight healthy human volunteers consumed a low-polyphenol diet for 24 h before drinking 400 mL of commercially available coffee. Plasma samples were collected over 24 h and analyzed by HPLC-MS(2) . Investigation of the mechanism of absorption and metabolism was performed using an intestinal Caco-2 cell model. For the first time, we show that dimethoxycinnamic acid appears in plasma as the free aglycone. The time to reach the C(max) value of approximately 0.5 μM was rapid, T(max) = 30 min, and showed an additional peak at 2-4h for several subjects. In contrast, smaller amounts of dimethoxy-dihydrocinnamic acid (C(max) ∼ 0.1 μM) peaked between 8 and 12 h after coffee intake. In the cell model, dimethoxycinnamic acid was preferentially transported in the free form by passive diffusion, and a small amount of dimethoxycinnamoylquinic acid hydrolysis was observed. These findings show that dimethoxycinnamic acid, previously identified in plasma after coffee consumption, was rapidly absorbed in the free form most likely by passive diffusion in the upper gastrointestinal tract.

Constituents in purple sweet potato leaves inhibit in vitro angiogenesis with opposite effects ex vivo

ObjectiveThe aim of this study was to investigate the in vitro effect of polyphenols in purple sweet potato leaves (PSPLs) on angiogenesis in human umbilical vascular endothelial cells (HUVECs). The ex vivo effect was test in human serum collected from the subjects who consumed 200 g of PSPL in a low polyphenol diet versus a low polyphenol diet. MethodsMethanolic extract from PSPLs and human sera from subjects were treated with HUVECs and the effects of cell proliferation, migration, tube formation, and matrix metalloproteinase activity were investigated. ResultsThe PSPL polyphenols at 0.2 to 0.6 mM gallic acid equivalents inhibited proliferation, migration, and tube formation of vascular endothelial growth factor–treated HUVECs. Further, the activity of secreted matrix metalloproteinase-2 was decreased by at least 13.8%. However, 5% PSPL serum increased migration and tube formation of HUVECs by 110% and 56.9%, respectively, compared with serum from subjects on the low polyphenol diet. Further, the activity of matrix metalloproteinase-9 was increased by 128% in the PSPL serum. ConclusionThese results suggest that PSPL polyphenols inhibited in vitro angiogenesis, but PSPL constituents might shift serum biochemistries to be more proangiogenic.

Pharmacokinetics of cranberry juice anthocyanins, flavonols, flavanols, and phenolic acids in urine

Phenolic acids and flavonoids in cranberries may account for some of their putative health benefits. We have previously characterized the plasma pharmacokinetics of phenolic acids (including sinapic, homovanillic, protocatechuic, and sinapic acids) and flavonols (including kaempferol, myricetin, and quercetin) in 10 healthy adults, 50–70 y old. After a 2-d run-in period following a low polyphenol diet, fasted subjects consumed 237 mL low-calorie, sugar-free cranberry juice cocktail (54% juice). To determine the pharmacokinetics of cranberry bioactives in urine, samples were collected at 0, 2, 4, 6, 8, 10, and 24 h after beverage consumption for determination of 13 phenolic acids, 2 flavanols, 3 flavonols, 6 anthocyanins, and 7 anthocyanin glucuronides. The maximal urinary concentration (Cmax) and time to reach Cmax (Tmax) among the cranberry cyanidin and peonidin glycosides were 0.2–0.9 ng/mg creatinine at 2.2–3.4 h. The Cmax and Tmax of 4 cyanidin glucuronides and 3 peonidin glucuronides were 0.9–41.1 ng/mg at 3.0–5.1 h, respectively. The variations in Cmax and Tmax for phenolic acids and other flavonoids were more pronounced with concentrations of 0.1–21.1 μg/mg at 3.8–18.8 h, respectively. These data suggest that cranberry phenolic acids and flavonoids are bioavailable and metabolized in healthy older adults. (Supported by USDA and Ocean Spray, Inc.)

Effect of purple sweet potato leaves consumption on exercise-induced oxidative stress and IL-6 and HSP72 levels

The aim of this study was to evaluate the effects of purple sweet potato leaves (PSPL) consumption on oxidative stress markers in a healthy, nontrained, young male population after completing a running exercise protocol. A crossover design was applied, with 15 subjects participating in a two-step dietary intervention period. Each subject was given a high- (PSPL group) or low-polyphenol (control group) diet for 7 days with a 14-day washout period. After each dietary intervention period, all subjects performed 1 h of treadmill running at a speed corresponding to 70% of each subject's individual maximal oxygen uptake (Vo(2max)). Blood samples were taken before exercise and at 0, 1, and 3 h after exercise. Compared with the control group, PSPL consumption significantly increased plasma total polyphenols concentration and total antioxidant power (i.e., the ferric-reducing ability of plasma) in the PSPL group. The markers of oxidative damage, plasma TBARS and protein carbonyl, significantly decreased. Plasma IL-6 concentration also decreased. However, no significant difference was found in HSP72 levels between the two groups. These findings indicate that consuming a high-polyphenol diet for 7 days can modulate antioxidative status and decrease exercise-induced oxidative damage and pro-inflammatory cytokine secretion.

English walnuts (Juglans regia L.) improve antioxidant capacity in humans

The consumption of English walnuts (Juglans regia L.) promotes cardiovascular health, in part due to its favorable effect on serum lipids. Walnut polyphenols, including ellagitannins (ET) may also contribute to this benefit. To determine whether consuming walnuts in amounts readily incorporated into the diet (0.75 and 1.50 oz) has a dose‐response effect on plasma antioxidant capacity, we conducted a randomized, crossover study with a 1 wk run‐in period, 6 wk interventions with each walnut dose, and a 6 wk washout period between these tests in 20 healthy, non‐smoking adults ≥50 y. Subjects followed a low ET diet during the entire 19 wk study, and a low polyphenol diet for 2 d prior to each visit. Walnut intake tended to increase selected measures of plasma antioxidant capacity in a dose‐dependent manner with a higher proportion of responders in the 1.50 vs. 0.75 oz group, particularly in women. These data suggest that walnuts may modestly improve antioxidant capacity in humans, revealing another potential mechanism to further support the FDA qualified health claim that the regular consumption of walnuts decreases the risk of heart disease. (Supported by USDA and California Walnut Commission)

English walnuts (Juglans regia L.) protect endogenous antioxidants in humans

Ellagic acid monomers, polymeric tannins and related phenolic compounds isolated from English walnuts (Juglans regia L.) have been reported to inhibit LDL oxidation ex vivo and decrease biomarkers of oxidative stress in animal models. To determine whether dietary and endogenous antioxidants are preserved following walnut consumption in humans, we conducted a pilot study in 3 healthy adults. Subjects followed a low polyphenol diet for 2 d prior to the intervention. Fasting blood was then collected at baseline (0 h) and 2 h after consuming a single dose (45 g) of walnuts (WC). Lipophilic free radical initiators were added ex vivo, ±10 μM GAE methanolic walnut extract (WE). The oxidizability of lipid and aqueous plasma components were measured over 4 h and results expressed as percent area under the time course curve. WE protected α‐tocopherol against oxidation at 0 h (P=0.045), but at 2 h the in vitro effect of WE was modest due to a contributing protective action by WC (P=0.021). At 2 h WE protected β‐carotene &gt; WC alone (P=0.039). However, the interactive effect of WC + WE was &gt; WE alone at 0 h (P=0.026). At 2 h, WC + WE also protected lycopene &gt; WE alone at 0 h (P=0.032). No changes in plasma antioxidant levels were observed at 2 h. These data suggest that walnuts may protect against oxidative damage in human plasma by preserving endogenous antioxidant defenses. (Supported by USDA and California Walnut Commission)

Consumption of purple sweet potato leaves decreases lipid peroxidation and DNA damage in humans.

Consumption of polyphenols is associated with reduced risk of chronic diseases, possibly via a variety of bio-mechanisms, including antioxidation and anti-inflammation. Purple sweet potato leaves (PSPL) commonly consumed in Asia possess polyphenols. In this study, we aim to investigate antioxidant effect of 200 g/d PSPL containing 902 mg polyphenols in a clinical trial. This randomized, crossover clinical study included 16 healthy adults (7 M, 9 F; aged 20-22 y). After a 1-wk run period, subjects were assigned randomly to receive either PSPL or low polyphenol diet (LPD) for 2 wks, followed by a 2-wk washout period before crossing over to the alternate diet. Fasting blood and 24-h urine samples were collected from each subject at day 0, 7 and 14 of each phase. Our data showed PSPL consumption enhanced urinary total phenol excretion by 24.5% at day 14 as compared to day 0, while the LPD decreased total phenol content in plasma and urine by 3.3 and 16.3%, respectively (p< or =0.05). Low-density lipoprotein lag time and glutathione concentration in erythrocytes at day 14 was significantly enhanced by 15.0 and 33.3% by PSPL as compared to day 0, respectively, while their values were not altered by the LPD. Urinary 8-hydoxy-deoxyguanosine (8-OHdG) excretion decreased significantly by PSPL consumptoin by 36.7% at day 7 as compared to day 0, yet unchanged by the LPD (p< or =0.05). In conclusion, our results suggest that polyphenols in 200 g PSPL were bioavailable and could enhance antioxidant defense and decrease oxidative stress in young healthy people.