Randomized controlled trial for an effect of green tea-extract powder supplementation on glucose abnormalities

OBJECTIVE: We examined whether green tea-extract powder supplementation improves glucose abnormality. METHODS: The study was conducted for volunteers who resided in eastern communities of Shizuoka Prefecture and who had fasting blood glucose levels of >or=6.1 mmol/l or nonfasting blood glucose levels of >or=7.8 mmol/l in a recent health check-up. Sixty subjects aged 32-73 years (49 males and 11 females) participated in the trial. The Early intervention group consumed a packet of green tea-extract powder containing 544 mg polyphenols (456 mg catechins) daily for the first 2 months and then entered the 2-month nonintervention period. The Later intervention group was observed for the first 2 months and then consumed green tea-extract powder as described above for the subsequent 2 months. Using the two-period crossover design, we analyzed the changes in fasting hemoglobin A1c level and other biomarkers in blood samples collected at baseline, 2 months and 4 months. RESULTS: A significant reduction in hemoglobin A1c level and a borderline significant reduction in diastolic blood pressure were associated with the intervention. The intervention caused no significant changes in weight, body mass index, body fat, systolic blood pressure, fasting serum glucose level, homeostasis model assessment index, serum lipid level or hypersensitive C-reactive protein. CONCLUSION: Daily supplementary intake of green tea-extract powder lowered the hemoglobin A1c level in individuals with borderline diabetes.     

Estimated Dietary Polyphenol Intake and Major Food and Beverage Sources among Elderly Japanese

Estimating polyphenol intake contributes to the understanding of polyphenols’ health benefits. However, information about human polyphenol intake is scarce, especially in the elderly. This study aimed to estimate the dietary intake and major sources of polyphenols and to determine whether there is any relationship between polyphenol intake and micronutrient intake in healthy elderly Japanese. First, 610 subjects (569 men, 41 women; aged 67.3 ± 6.1 years) completed food frequency questionnaires. We then calculated their total polyphenol intake using our polyphenol content database. Their average total polyphenol intake was 1492 ± 665 mg/day, the greatest part of which was provided by beverages (79.1%). The daily polyphenol intake differed largely among individuals (183–4854 mg/day), also attributable mostly to beverage consumption. Coffee (43.2%) and green tea (26.6%) were the major sources of total polyphenol; the top 20 food items accounted for >90%. The polyphenol intake did not strongly correlate with the intake of any micronutrient, suggesting that polyphenols may exert health benefits independently of nutritional intake. The polyphenol intake in this elderly population was slightly higher than previous data in Japanese adults, and beverages such as coffee and green tea contributed highly to the intake.     

Green tea polyphenols provide photoprotection, increase microcirculation, and modulate skin properties of women

Dietary constituents including polyphenols and carotenoids contribute to endogenous photoprotection and modulate skin characteristics related to structure and function of the tissue. Animal and in-vitro studies indicate that green tea polyphenols affect skin properties. In a 12-wk, double-blind, placebo-controlled study, 60 female volunteers were randomized to an intervention or control group. Participants consumed either a beverage with green tea polyphenols providing 1402 mg total catechins/d or a control beverage. Skin photoprotection, structure, and function were measured at baseline (wk 0), wk 6, and wk 12. Following exposure of the skin areas to 1.25 minimal erythemal dose of radiation from a solar simulator, UV-induced erythema decreased significantly in the intervention group by 16 and 25% after 6 and 12 wk, respectively. Skin structural characteristics that were positively affected included elasticity, roughness, scaling, density, and water homeostasis. Intake of the green tea polyphenol beverage for 12 wk increased blood flow and oxygen delivery to the skin. Likewise, in a separate, randomized, double-blind, single-dose (0.5, 1.0, and 2.0 g) study of green tea polyphenols, blood flow was maximized at 30 min after ingestion. In summary, green tea polyphenols delivered in a beverage were shown to protect skin against harmful UV radiation and helped to improve overall skin quality of women.     

Improvement of blood lipid profiles by Goishi tea polyphenols in a randomised,double-blind,placebo-controlled clinical study

Dyslipidaemia is a risk factor for arteriosclerosis. Recent studies have shown that dyslipidaemia is effectively prevented by various polyphenols. In this clinical study (UMIN trial: 000024028), we evaluated the beneficial effects of polyphenols contained in Goishi tea on blood lipid profiles. Seventy-seven subjects with LDL cholesterol (CHO) ≧120?mg/mL were randomly divided into two groups for 12 weeks of polyphenol intake as follows: the Goishi tea group for daily consumption of Goishi tea containing 122?mg of polyphenols and the placebo group for the corresponding consumption of a placebo drink containing 12.2?mg of polyphenols. Intake of Goishi tea polyphenols tended to increase HDL CHO and suppress the elevation of triglycerides. These effects were particularly notable among the subjects with a body mass index <25?kg/m². These findings suggest that Goishi tea polyphenols may suppress arteriosclerosis and reduce cardiovascular event risk by improving blood lipid profiles and thereby preventing dyslipidaemia.     

Serum gamma-glutamyltransferase is inversely associated with dietary total and coffee-derived polyphenol intakes in apparently healthy Japanese men

Purpose

Serum γ-glutamyltransferase (GGT) has been proposed as a marker of oxidative stress. Here, we examined the association between serum GGT and the dietary intake of polyphenols, which have antioxidant properties.

Methods

A cross-sectional survey including 7960 apparently healthy Japanese men (aged 22–86 years) who participated in health checkups was conducted in Shizuoka, Japan. We analyzed these subjects’ clinical serum parameters and lifestyle factors, including dietary polyphenol intake, which was evaluated by a self-administered questionnaire and by matching the subjects’ food consumption data with our original polyphenol content database.

Results

The average intake of polyphenols was 1157?±?471 mg/day, and green tea was the largest source of polyphenols at 40%, followed by coffee at 36%. Dividing the population according to quintiles of total polyphenol intake, the difference in polyphenol intake from coffee between the groups was much greater than the difference in polyphenol intake from green tea. The analysis of the association between polyphenol intake and biological parameters showed a significant negative association between polyphenol intake and the levels of systolic and diastolic blood pressure (SBP and DBP), GGT, and alanine aminotransferase (ALT) after adjusting for age, smoking habit, energy intake and alcohol intake. The GGT levels were inversely associated with the polyphenol intake from coffee, but not with that from green tea. Multivariable linear regression analyses demonstrated that the subjects’ GGT levels were negatively and independently associated with their polyphenol intake.

Conclusions

The intake of total polyphenol including coffee as a major contributor is inversely associated with the serum GGT concentration in Japanese males.

     

Green tea improves metabolic biomarkers,not weight or body composition: a pilot study in overweight breast cancer survivors

Background: Overweight status after breast cancer treatment may increase a woman’s risk for recurrent disease and/or early onset cardiovascular disease. Green tea has been proposed to promote weight loss and favourably modify glucose, insulin and blood lipids. This pilot study tested the effect of daily decaffeinated green tea consumption for 6 months on weight and body composition, select metabolic parameters and lipid profiles in overweight breast cancer survivors. Methods: The effect of daily decaffeinated green tea intake on weight, body composition and changes in resting metabolic rate, energy intake, glucose, insulin, homeostasis model assessment – insulin resistance (HOMA‐IR) and lipids was evaluated in overweight breast cancer survivors. Participants had a mean weight of 80.2 kg; body mass index (BMI) 30.1 kg m^?2; and body fat 46.4%. Participants (n = 54) were randomised to 960 mL of decaffeinated green or placebo tea daily for 6 months. Results: Mean (SD) tea intake among study completers (n = 39) was 5952 (1176) mL week^?1 and was associated with a significant reduction in energy intake (P = 0.02). Change in body weight of ?1.2 kg (green tea) versus +0.2 kg (placebo) suggests a weight change effect, although this was not statistically significant. Decaffeinated green tea intake was associated with elevated high‐density lipoprotein (HDL) levels (P = 0.003) and nonsignificant improvements in the HDL/LDL ratio and HOMA‐IR (?1.1 ± 5.9: green tea; +3.2 ± 7.2: herbal). Conclusions: Intake of decaffeinated green tea for 6 months was associated with a slight reduction in body weight and improved HDL and glucose homeostasis in overweight breast cancer survivors.     

The polyphenol content and antioxidant activities of the main edible vegetables in northern Vietnam

Oxidized low-density lipoprotein (LDL) is considered a risk factor in atherosclerosis, and polyphenols are the potential agents to inhibit the oxidation of LDL. We determined the polyphenol contents and the antioxidant activities of commonly consumed vegetables in Vietnam and assessed the quantity of the polyphenol intake from vegetables in the current Vietnamese diet. The polyphenol contents in 30 kinds of vegetables was determined by the Folin-Ciocalteu method. The antioxidant activities of vegetables were evaluated by measuring the oxidation of LDL and the reduction of the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical. In this study, some herbs and edible wild vegetables possessed high contents of polyphenols and antioxidant activities. Among green vegetables, sweet potato leaves showed both a high polyphenol content and antioxidant activity. The mean polyphenol daily intake of the Vietnamese was a 595 mg catechin equivalent. Water spinach, a kind of green vegetable, contributed the highest amount (45%) of the total polyphenol intake, followed by other green vegetables. Neither herbs nor edible wild vegetables contributed significantly to the total polyphenol intake due to their low consumption. Green vegetables are therefore considered very important sources of polyphenol intake for the Vietnamese.     

Effects of dietary supplementation with the green tea polyphenol epigallocatechin-3-gallate on insulin resistance and associated metabolic risk factors: randomized controlled trial

Animal evidence indicates that green tea may modulate insulin sensitivity, with epigallocatechin-3-gallate (EGCG) proposed as a likely health-promoting component. The purpose of this study was to investigate the effect of dietary supplementation with EGCG on insulin resistance and associated metabolic risk factors in man. Overweight or obese male subjects, aged 40-65 years, were randomly assigned to take 400 mg capsules of EGCG (n 46) or the placebo lactose (n 42), twice daily for 8 weeks. Oral glucose tolerance testing and measurement of metabolic risk factors (BMI, waist circumference, percentage body fat, blood pressure, total cholesterol, LDL-cholesterol, HDL-cholesterol, TAG) was conducted pre- and post-intervention. Mood was evaluated weekly using the University of Wales Institute of Science and Technology mood adjective checklist. EGCG treatment had no effect on insulin sensitivity, insulin secretion or glucose tolerance but did reduce diastolic blood pressure (mean change: placebo - 0.058 (se 0.75) mmHg; EGCG - 2.68 (se 0.72) mmHg; P = 0.014). No significant change in the other metabolic risk factors was observed. The EGCG group also reported feeling in a more positive mood than the placebo group across the intervention period (mean score for hedonic tone: EGCG, 29.11 (se 0.44); placebo, 27.84 (se 0.46); P = 0.048). In conclusion, regular intake of EGCG had no effect on insulin resistance but did result in a modest reduction in diastolic blood pressure. This antihypertensive effect may contribute to some of the cardiovascular benefits associated with habitual green tea consumption. EGCG treatment also had a positive effect on mood. Further studies are needed to confirm the findings and investigate their mechanistic basis.     

The relation between single/double or repeated tea catechin ingestions and plasma antioxidant activity in humans

OBJECTIVE: The purpose of this study was to investigate the effects of single/double or repeated intake of a normal amount of tea catechin on plasma catechin concentrations and antioxidant activity in young women. DESIGN: First, after an overnight fast, five healthy subjects were given water or single/double dose(s) of tea polyphenol extract (164 mg tea catechins containing 61% epigallocatechin gallate in 190 ml water). Blood samples were taken before and 30, 60 and 180 min after the ingestion. Second, 16 healthy subjects ingested the tea polyphenol extract three times a day at mealtimes for 7 days followed by withdrawal of tea polyphenol extract for 7 days. Blood samples were taken before and after ingestion, and 7 days after the withdrawal of tea catechin. Subjects were prohibited from drinking any beverages containing polyphenols or antioxidant supplements during the study period. Catechin and other antioxidant concentrations in the plasma were measured, and changes in antioxidant activity were evaluated by ferric reducing ability of plasma assay. RESULTS: Single/double ingestion of tea polyphenol extract did not cause an increase in the antioxidant activity. There was no also change in antioxidant activity after the ingestion of tea polyphenol extract for 7 days. Plasma-free epigallocatechin gallate concentration remained at the pre-study level; however, the plasma FRAP value decreased significantly at 7 days after the withdrawal of tea polyphenol extract. Decreases in endogenous antioxidants in the plasma, including vitamin C and bilirubin, were also observed 7 days after withdrawal of tea polyphenol. CONCLUSIONS: The results suggest that continuous daily intake of tea catechins affects the concentrations of endogenous antioxidants in the plasma and has the potential to maintain total antioxidant activity.     

Green tea supplementation ameliorates insulin resistance and increases glucose transporter IV content in a fructose-fed rat model

Summary.Background: Sprague-Dawley rats fed a fructose-rich diet exhibit insulin resistance and hypertension, a pathologic status resembling human type II diabetes mellitus, and are an excellent laboratory animal model for research on insulin action and the development of hypertension. Since green tea has numerous beneficial effects, we tested its effect on fructose-fed rats. Aim: The present study was therefore designed to further evaluate the effects of green tea supplementation on insulin resistance, hypertension, and the glucose transporters I and IV contents in adipose tissue in the fructose-fed rat model.Methods: The animals were divided into three groups and fed for 12 weeks with standard chow and water (control group), a high fructose diet and water (fructose group), or the same high fructose diet, but with green tea (0.5 g of lyophilized green tea powder dissolved in 100 mL of deionized distilled water) instead of water (fructose/green tea group). During the 12 weeks study period, fresh water or green tea was provided daily at 6:00 PM. Blood pressure was measured twice a week, and an oral glucose tolerance test performed after 12 weeks of diet supplementation.At the end of the experiment, plasma triglyceride (TG), free fatty acid (FFA), glucose, and insulin were assayed. The epididymal fat pads from all rats in the same group were pooled and adipocytes isolated and tested for insulin binding, glucose uptake, and their content of glucose transporters I (GLUT I) and IV (GLUT IV).Result: Compared to the control group, the fructose group developed fasting hyperglycemia, hyperinsulinemia, and elevated blood pressure. Insulin-stimulated glucose uptake and insulin binding of adipocytes were significantly reduced, and the glucose transporter IV content of adipocytes also decreased. The fructose/green tea group showed improvement in all of these metabolic defects and in insulin resistance and blood pressure.Conclusion: Based on these results, we suggest that the amelioration of insulin resistance by green tea is associated with the increased expression of GLUT IV.     

Black and green tea polyphenols attenuate blood pressure increases in stroke-prone spontaneously hypertensive rats

Oxidative stress was reported to be involved not only in cardiovascular diseases, but also in hypertension. Epidemiologic studies indicated that tea consumption slightly reduces blood pressure. We conducted two studies to determine whether black and green tea can lower blood pressure (BP) in stroke-prone spontaneously hypertensive rats (SHRSP). Male SHRSP (n=15) were allowed to recover for 2 wk after a transmitter for measuring BP was implanted in the peritoneal cavity. The rats were divided into three groups: the control group consumed tap water (30 mL/d); the black tea polyphenol group (BTP) consumed water containing 3.5 g/L thearubigins, 0.6 g/L theaflavins, 0.5 g/L flavonols and 0.4 g/L catechins; and the green tea polyphenol group (GTP) consumed water containing 3.5 g/L catechins, 0.5 g/L flavonols and 1 g/L polymetric flavonoids. The telemetry system was used to measure BP, which were recorded continuously every 5 min for 24 h. During the daytime, systolic and diastolic BP were significantly lower in the BTP and GTP groups than in the controls. Protein expressions of catalase and phosphorylated myosin light chain (MLC-p) were measured in the aorta by Western blotting. GTP significantly increased catalase expression, and BTP and GTP significantly decreased MLC-p expression in the aorta. These data demonstrate that both black and green tea polyphenols attenuate blood pressure increases through their antioxidant properties in SHRSP. Furthermore, because the amounts of polyphenols used in this experiment correspond to those in approximately 1 L of tea, the regular consumption of black and green tea may also provide some protection against hypertension in humans.     

Health effects of green tea catechins in overweight and obese men: a randomised controlled cross-over trial

Regular consumption of green tea may be cardioprotective. In the present study we investigated the health effects of dietary supplementation with green tea catechins and the potential modifying effect of the catechol-O-methyltransferase (COMT) Val/Met genotype. Subjects (sedentary males, aged 40-69 years, with BMI ≥ 28 and ≤ 38 kg/m(2)) were randomly assigned to consume decaffeinated green tea extract (DGT; 530 mg containing about 400 mg total catechins/capsule, twice daily) and placebo in a complete cross-over design. Ambulatory blood pressure and biomarkers of metabolic function (cholesterol, TAG, glucose and insulin) were measured at weeks 0 and 6. Although a marked increase in the concentration of plasma epigallocatechin gallate (EGCG), urinary epigallocatechin (EGC) and urinary 4'-O-methyl EGC was found after DGT treatment, no effect on blood pressure or biomarkers of metabolic function was observed. However, a period × treatment interaction (P < 0·05) was detected for body-weight change. Despite a similar increase in estimated energy intake during intervention period 1, body weight decreased by 0·64 (sd 2·2) kg and increased by 0·53 (sd 1·9) kg in the DGT and placebo groups, respectively (P = 0·025), suggesting a protective effect of green tea catechins on weight gain. Additionally, the COMT Val/Met genotype influenced urinary accumulation of EGC and 4'-O-methyl EGC (P < 0·01). Mean concentrations were lower in individuals homozygous for the high-activity G-allele, possibly reflecting increased metabolic flux and a more rapid conversion to downstream metabolic species, compared with individuals carrying at least one copy of the low-activity A-allele. Additional studies are needed to confirm these findings and further explore the modifying effect of genotype.     

绿茶及其有效成分对肾性高血压大鼠左室肥厚抑制作用的研究

目的研究绿茶及其提取物对肾性高血压大鼠左室肥厚的抑制作用机制。方法雄性Wistar大鼠160只,体重180~220g,随机分为5组,建立二肾一夹法大鼠肾性高血压左室肥厚模型:假手术组(SHAM)和手术组(2K1C)正常饮水;手术+绿茶组(2K1C+GT)饮用2%绿茶水;手术+茶多酚组(2K1C+TP)饮用0.1%茶多酚水;手术+EGCG组(2K1C+EGCG)饮用0.05%EGCG水,术后即给予不同浓度的绿茶及其提取物,持续8周直至实验结束。结果与假手术组比较,手术组和各饮茶组血压、左心室与体重比值(LVW/BW)和左心室壁厚度(LVWT)均显著升高(P<0.01)。而与手术组相比,不同浓度的绿茶及其有效成分(2%绿茶、0.1%茶多酚、0.05%EGCG)左心室重/体重(LVW/BW)、左心室壁厚度显著降低,抗氧化酶(SOD和GSH-Px)的活性升高,活性氧自由基(ROS)以及Ras和ERK1/2蛋白表达降低,但对大鼠收缩压无显著性影响。结论绿茶及其提取物对肾性高血压大鼠左室肥厚有抑制作用,其机制可能是由于茶及其有效成分具有抗氧化活性,能够清除ROS,以及对Ras-MAPK信号传导通路的调控有关。     

The Effects of Green Tea on Diabetes and Gut Microbiome in db/db Mice: Studies with Tea Extracts vs. Tea Powder

Green tea extracts and tea catechins have been shown to prevent or alleviate diabetes. The present study tests the hypothesis that green tea leaves in powder form (GTP), which also contain fiber and other water non-extractable materials, are more effective than the corresponding green tea extracts (GTE) in impeding the development of diabetes in db/db mice. Female db/db mice were treated with a diet containing 1% of GTE, 2% of GTE, 2% of GTP (with the same catechin content as 1% GTE) or 1% GTP. The 1% GTE group had lower food intake, water consumption, body weight and fasting blood glucose levels than the control group, while 2% GTP did not have any significant effect. Dietary 1% GTE also preserved β-cell insulin secretion. However, 1% GTP increased food intake, water consumption and blood glucose levels. Microbiome analysis with 16S rRNA gene V4 sequencing showed that the gut microbiota was modified by GTE and GTP, and a few bacterial guilds were associated with blood glucose levels. In the Random Forest regression model, the leading predictor of metabolic outcome was food consumption, followed by changes in some bacterial guilds. The results illustrate the importance of food consumption and gut microbiota in affecting the progression of diabetes.     

The Relationship between Dietary Polyphenol Intakes and Urinary Polyphenol Concentrations in Adults Prescribed a High Vegetable and Fruit Diet

Urinary polyphenol metabolites are potential biomarkers of dietary polyphenol intake. The current study aims to evaluate associations between total diet, vegetable and fruit polyphenol intakes with urinary polyphenol metabolite concentrations in a sample of adults prescribed a diet rich in vegetables and fruit. Thirty-four participants completed a 10-week pre-post study. Participants were asked to consume Australian recommended daily vegetable and fruit serves and attend measurement sessions at baseline and at weeks 2 and 10. Two 24-h diet recalls were collected at each time-point and polyphenol intakes were calculated using the Phenol-Explorer database. Spot urine samples, collected at each time-point, were analyzed for 15 polyphenol metabolites using liquid chromatography-mass spectroscopy. Spearman’s correlation analyzes assessed the strength of relationships between urinary and dietary polyphenols. Linear mixed models were used to investigate relationships between polyphenol excretion and intake. Total urinary polyphenols were significantly correlated with total polyphenol intakes at week 10 (r_s = 0.47) and fruit polyphenols at week 2 (r_s = 0.38). Hippuric acid was significantly correlated with vegetable polyphenols at baseline (r_s = 0.39). Relationships were identified between individual polyphenol metabolites and vegetable and fruit polyphenols. Linear mixed model analyzes identified that for every 1 mg increase in polyphenol intakes, urinary polyphenol excretion increased by 16.3 nmol/g creatinine. Although the majority of relationships were not sufficiently strong or consistent at different time-points, promising relationships were observed between total urinary polyphenols and total polyphenol intakes, and hippuric acid and vegetable polyphenols.     

绿茶保健作用研究

[目的]探讨绿茶保健作用。[方法]应用722分光光度仪测定绿茶中茶多酚含量,应用原子吸收分光光度仪测定微量元素含量及溶出率。[结果](1)绿茶等级越高其氨基酸、茶多酚的含量越高,锌含量亦越高。不同等级间茶多酚、微量元素锌含量差别甚大,茶多酚含量高者达36.2%,低者仅10.9%。锌含量高者达53.2μg/g,低者仅35.25μg/g。(2)铜、铁含量不高且品种间差别不大。(3)锰、氟、铝含量则随茶叶等级降低而升高,且品种间含量差别甚大。(4)5种绿茶中锌的溶出率均较高,达79.95%～88.26%,铜达70.6%～92.89%,氟达72.75%～95.63%,铁多为35%左右,锰36.08%～44.66%,铝8.81%～51.69%。[结论]高级别绿茶具有保健作用,低级别绿茶无益于健康。     

硒对氟中毒致大鼠肾脏损伤的干预作用

目的探讨硒对氟致大鼠肾脏损伤的干预作用。方法实验以雄性SD大鼠为动物模型分为预防试验、治疗试验。预防试验以先水后氟为对照组,即大鼠先饮用自来水后饮用50mg/L的氟化钠溶液,3个先硒后氟组分别先饮用0.375、0.75、1.5mg/L的亚硒酸钠溶液,再饮用50mg/L的氟化钠溶液,先后暴露的时间各为6个月。治疗试验与预防试验喂养顺序相反,以先氟后水为对照组,3个先氟后硒组,氟化钠和亚硒酸钠溶液浓度与预防试验相同,先后暴露时间也各为6个月。染毒完毕后测定大鼠肾脏组织的氧化水平和核因子κB(NF-κB)的表达水平。结果预防试验中,与先水后氟对照组相比,先低硒后氟组和先中硒后氟组GSH-Px活性显著升高(P<0.05);先低硒后氟组丙二醛(MDA)含量显著降低(P<0.05),NF-κB的表达水平显著降低(P<0.05)。治疗试验各项指标均无统计学差异(P>0.05)。结论硒对氟中毒致大鼠肾脏损伤的干预方式中,硒的预防效果好于治疗效果,其中0.375mg/L是本实验条件下硒对慢性氟中毒致大鼠肾脏损伤的较有效的预防作用剂量,NF-κB表达水平的变化可能是硒对氟中毒预防作用的关键环节之一。     

Dietary sources of polyphenols in the Mediterranean healthy Eating,Aging and Lifestyle (MEAL) study cohort

The aim of this study was to estimate the dietary intake and major food sources of polyphenols in the Mediterranean healthy Eating, Aging and Lifestyles (MEAL) study cohort. A total of 1937 individuals (18?+?y) of urban population of Catania, Italy, completed a validated 110-item food frequency questionnaire; Phenol-Explorer database was used to estimate polyphenol intake. Mean intake of polyphenols was 663.7?mg/d; the most abundant classes were phenolic acids (362.7?mg/d) and flavonoids (258.7?mg/d). The main dietary sources of total polyphenols were nuts, followed by tea and coffee as source of flavanols and hydroxycinnamic acids, respectively, fruits (i.e. cherries were sources of anthocyanins and citrus fruits of flavanones) and vegetables (i.e. artichokes and olives were sources of flavones and spinach and beans of flavonols); chocolate, red wine and pasta contributed to flavanols and tyrosols, respectively. These findings will be useful to assess the potential benefits of foods with high polyphenol content.     

Estimated dietary intake and major food sources of polyphenols in the Polish arm of the HAPIEE study

ObjectiveThe aim of this study was to estimate the intake of known individual polyphenols and their major dietary sources in the Polish arm of the HAPIEE (Health, Alcohol and Psychosocial factors In Eastern Europe) study.MethodsA total of 10,477 random sample (45–69 y) of urban population of Krakow, Poland, completed a validated 148-item food frequency questionnaire. Polyphenol intake was calculated by matching food consumption data with the recently developed Phenol-Explorer database.ResultsThe mean intake of polyphenols was 1756.5 ± 695.8 mg/d (median = 1662.5 mg/d). The main polyphenol groups were flavonoids (897 mg/d) and phenolic acids (800 mg/d). A total of 347 polyphenols from 19 polyphenol subclasses were found. The individual compounds with the highest intakes were isomers of chlorogenic acid (i.e., 5-caffeoylquinic acid and 4-caffeoylquinic acid) among hydroxycinnamic acids (average intake 150 mg/d), that largely originated from coffee, and compounds belonging to the catechin chemical family (i.e., [+]-gallocatechin, [-]-epigallocatechin 3-O-gallate, and [-]-epicatechin) among flavanols (average intake 50 mg/d), that mostly originated from tea and cocoa products.ConclusionsThe current study provides the most updated data for individual polyphenols intake in the diet of a well-established nutritional cohort. These findings will be useful to assess potential beneficial role on health of specific foods with high polyphenol content and characterize the effects of individual phenolic compounds.     

Estimated daily intake of phenolics and antioxidants from green tea consumption in the Korean diet

To estimate daily intake of total phenolics and flavonoids from green tea and the contribution of green tea to the antioxidant intake from the Korean diet, 24 commercial brands of green tea were selected and analyzed. Data from the Korea National Health and Nutrition Examination Survey (KNHANES) from 2008 and 2011 indicate that the green tea consumption in these 2 years was 2.8?g/tea drinker/day and 2.9?g/tea drinker/day, respectively. Based on data derived from direct measurements of green tea phenolics and the dataset of the 2008 KNHANES, we estimated the daily per tea drinker phenolics intake to be 172?mg gallic acid equivalents (GAE), the total flavonoids to be 43?mg catechin equivalents (CE) and the total antioxidants to be 267?mg vitamin C equivalents (VCE; 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay) and 401?mg VCE (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) assay). In 2011, we estimated the daily per tea drinker total phenolics intake to be 246?mg GAE, the total flavonoids to be 60?mg CE and the antioxidants to be 448?mg VCE (DPPH assay) and 630?mg VCE (ABTS assay). The daily intake of total phenolics, total flavonoids and antioxidants from green tea consumption increased from 2008 to 2011.