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PubMed2004

[The green tea, a good choice for cardiovascular disease prevention?].

Tea (Camellia sinensis) has been used for centuries as a medical drink. Around two-thirds of the world's population drink tea. It is originated from southern China and entensive cultivated in Asia and in central African countries. Tea can be grouped into three main types, black, oolong, and green tea. Green tea is not fermented and is a major beverage consumed in Asian countries. Green tea is produced from freshly harvest leaves of the tea plant and they contain water, proteins, carbohydrates, minerals, vitamins and polyphenols of the flavonoid type. The major flavonoids in green tea are catechins which constitute about one third of its total dry weight. The major catechin present is epigallocatechin gallate (>50%). New data have increased the interest in green tea or its catechins and its role in treatment of cardiovascular disease (CHD) risk factors. The aim of the present paper is to review some studies that have found a relationship between green tea and CHD risk factors. From some of them it can be summarized that of green tea and its catechins consumptions (i) decrease body weight by interfering within the sympathoadrenal system and fatty acid synthesis, (ii) decrease cholesterol absorption and plasma levels, (iii) have strong free radical-scavenging activity inhibiting LDL oxidation, (iv) reduce the adhesion molecule expression, (v) have antitrombotic activities by inhibiting platelet aggregation and (vi) decrease systolic and diastolic blood pressures. The positive effects found suggest that a daily intake of 7 cups of green tea (3.5 g catechins) is a good choose for CHD prevention; however, it is still necessary more studies to check the action of the green tea and its catechins in humans in order to recommended its use in the general population or only in target subjects.

Antioxidants↗
PubMedDate not supplied

Serum antioxidant vitamin levels of people in Khon Kaen, northeastern Thailand.

Three antioxidant vitamins, the alpha- and beta-carotenes as well as vitamin E, were measured in sera of a normal population in Northeastern Thailand using HPLC. The mean serum beta-carotene level of females was significantly higher than the value for males, i.e, 37.55 (95%CI=34.59-40.51) versus 32.97 (95% CI=30.01-35.93) micro/dl. The beta-carotene level tended to decrease as age increased, particularly in the male population. The mean serum beta-carotene level was also higher in females than in males, i.e., 7.08 (95%CI=6.57-7.59) and 6.26 (95% CI=5.77-6.75) micro/dl, respectively. The average serum alpha-tocopherol (Vitamin E) level of the whole population was 1.08 (95% CI=1.04-1.12) micro/dl and did not show age or sex differences. In general, the serum antioxidant vitamins of smokers were lower than those of the non-smokers but a significant difference was observed only for alpha-tocopherol. Alcohol drinking resulted in slightly lower serum beta-carotene values, whereas coffee or tea drinking and betel nut chewing did not cause any differences with these three antioxidant vitamins. However, we report higher in serum beta-carotene levels of people in Ban Fang district than in Chonnabot district. The results from our study give the base line data of serum antioxidant vitamins in a Thai population and also suggest future intensive study on the relationship of dietary intake and cancer prevention.

Adult↗
PubMed2000

Chemoprevention of tea on colorectal cancer induced by dimethylhydrazine in Wistar rats.

AIM:To investigate the chemopreventive effects of green tea and tea pigment on 1,2-dimethylhydrazine (DMH)-induced rat colorectal carcinogenesis.METHODS:Male weaning Wistar rats were randomly allocated into four groups.Rats in the positive control group were given a(c)s.c. injection of DMH, once a week for ten weeks;rats in tea treated groups, with the same DMH treatment as in the positive group, received 2% green tea and 0.1% tea pigments; rats in the negative control group were given s.c.injection of the same volume of saline as well as DMH in the positive group. Animals were sacrified and necropsied at the end of week 16 and week 32.RESULTS:Aberrant cryptic foci (ACF) were formed in animals in DMH-treated groups at the end of week 16. Compared to the DMH group, green tea and tea pigments groups had less ACF (148.25 and 204.25, respectively, P<0.01). At the end of week 32, all rats in DMH group developed large intestinal tumors. The results also showed that DMH increased labeling index (LI) of proliferating cell nuclear antigen (PCNA) of intestinal mucosa and the expression of ras-p21. However, in the tea-treated groups, PCNA-LI was significantly reduced as compared with the positive control group (36.63 and 40.36 in the green tea group and tea pigment group, respectively, at the end of the experiment,P<0.01).ras-p21 expression was also significantly reduced (2.07 and 2.36 in the colon tumors of rats in the green tea group and tea pigments group, respectively at the end of the experiment, P<0.01). Furthermore, green tea and tea pigment inhibited the expression of Bcl-2 protein (2, 5, 1, 0 and 2, 4, 1, 0,respectively, at the end of the experiment P<0.01), and induced expression of Bax protein (0,1,3,4 and 0,1,4,3, respectively, P <0.01).CONCLUSION:Chinese green tea drinking inhibited ACF and colonic tumors formation in rats, which showed that tea had a significant chemopreventive effect on DMH-induced colorectal carcinogenesis. Such effects may be due to suppression of cell proliferation and induction of apoptosis in the intestinal crypts.

Journal Article↗
PubMed1991

Fluoride intake and its safety among heavy tea drinkers in a British fluoridated city.

Tea-drinking in very young children has been studied in a British city. The results suggested that the fluoride in tea would, in some cases, be sufficient to influence caries. Clinical findings to some extent supported this. The main purpose of the investigation reported here was to determine maximum possible fluoride intake in adults who were heavy tea drinkers in a fluoridated city and relate it to toxic thresholds. Heavy tea drinkers were traced through Health Visitors and voluntary organizations and the volumes and fluoride concentrations of their drinks were measured. Even the highest intake found (9 mg) is below the probable intake in Bartlett, Texas (8 ppm of fluoride), in relation to which no undesirable symptoms have been reported (Leone et al. 1954). This confirms the safety of fluoridation. The effects on fluoride concentration of evaporating soft and hard fluoride-containing waters to small bulk were compared. The results showed ceilings of 3 ppm of fluoride in hard water and about 14 ppm in soft water, much higher than the levels expected on the basis of the usually stated solubility of CaF2 (16 or 8 ppm of fluoride). However, under normal household conditions, it is most unlikely that dangerous levels of fluoride would be ingested from boiled water.

Adult↗
PubMed2004

Effect of a 4-month tea intervention on oxidative DNA damage among heavy smokers: role of glutathione S-transferase genotypes.

Glutathione S-transferase (GST), a member of the phase II group of xenobiotic metabolizing enzymes, has been intensively studied at the levels of phenotype and genotype. The GST mu 1 (GSTM1) and GST theta 1 (GSTT1) genes have a null-allele variant in which the entire gene is absent. The null genotype for both enzymes has been associated with many different types of tumors. The aim of this study was to determine the possible differences in increased oxidative stress susceptibility to smoking within the GSTM1 and GSTT1 genotypes and the impact of high tea drinking on this. We designed a Phase II randomized, controlled, three-arm tea intervention trial to study the effect of high consumption (4 cups/day) of decaffeinated green or black tea, or water on oxidative DNA damage, as measured by urinary 8-hydroxydeoxyguanosine (8-OHdG), among heavy smokers over a 4-month period and to evaluate the roles of GSTM1 and GSTT1 genotypes as effect modifiers. A total of 133 heavy smokers (100 females and 33 males) completed the intervention. GSTM1 and GSTT1 genotype statuses were determined with a PCR-based approach. Multiple linear regression models were used to estimate the main effects and interaction effect of green and black tea consumption on creatinine-adjusted urinary 8-OHdG, with or without adjustment for potential confounders. Finally, we studied whether the effect of treatment varied by GSTM1 and GSTT1 status of the individual. Although there were no differences in urinary 8-OHdG between the groups at baseline, the between-group 8-OHdG levels at month 4 were statistically significant for GSTM1-positive smokers (P = 0.05) and GSTT1-positive smokers (P = 0.02). GSTM1-positive and GSTT1-positive smokers consuming green tea showed a decrease in urinary 8-OHdG levels after 4 months. Assessment of urinary 8-OHdG after adjustment for baseline measurements and other potential confounders revealed significant effect for green tea consumption (P = 0.001). The change from baseline was significant in both GSTM1-positive (t = -2.99; P = 0.006) and GSTT1-positive (P = 0.004) green tea groups, but not in the GSTM1-negative (P = 0.07) or GSTT1-negative (P = 0.909) green tea groups. Decaffeinated black tea consumption had no effect on urinary 8-OHdG levels among heavy smokers. Our data show that consumption of 4 cups of tea/day is a feasible and safe approach and is associated with a significant decrease in urinary 8-OHdG among green tea consumers after 4 months of consumption. This finding also suggests that green tea intervention may be effective in the subgroup of smokers who are GSTM1 and/or GSTT1 positive.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed1989

[Fluoride content of tea and amount ingested by children].

The fluoride concentration on their respective infusions was determined in the twelve most popular brand of tea which can be obtained in Valparaiso, Chile. Fluoride concentration was measured 5, 45 and 180 minutes after tea preparation, by using an specific fluoride electrode. The amount of ingestion of tea in children was estimated by means of a survey on 303 children from a sample of 7,690 boys and girls living in a fluoridated area. The data revealed a large variability in fluoride concentration depending on the brand of tea. Mean fluoride concentration was 2.36 mg F/l. at the five first minutes. Sixty eight per cent of children drinking tea as usual beverage, therefore it was estimated that about 22.1% of this sample have risk of dental fluorosis.

Child↗
PubMed2001

[Cause of bisphenol A migration from cans for drinks and assessment of improved cans].

In the previous investigation, we found that some cans for coffee and black tea drinks released large amounts of bisphenol A (BPA) into their contents. Equivalent cans were obtained and the cause of BPA migration was investigated. Equivalent cans A, B and D contained high levels of BPA in the side seam, in the bottom, and in the bottom and the side seam, respectively, while can C contained some level of BPA in the body, which has a large area, therefore, all of them contained high amounts of BPA in their coatings. In the migration test, there was no BPA migration from the cans into water at 60 and 95 degrees C for 30 min, into 20% ethanol at 60 degrees C for 30 min, or into n-heptane at 25 degrees C for 60 min. However, at 120 degrees C for 30 min, equivalent cans released 35-124 ng/mL BPA into the water. The total migration was similar to the total residues of BPA in the can coating and was close to the total amount of BPA in the drinks. Thus, BPA migration from the can coating requires heating to more than 105 degrees C, which is the glass transition temperature of the epoxy resin. Improved cans which contained less than 1/10 as much BPA as the equivalent cans showed very low migration levels, i.e., 3-6 ng/mL.

Benzhydryl Compounds↗
PubMed2000

Antioxidant activity of soya hypocotyl tea in humans.

Antioxidative activity of isoflavones has not been shown in humans. Newly-developed isoflavone-rich soya hypocotyl tea contains about 12 mg isoflavones per liter. 15 tea drinkers and 23 control young female students were randomly selected from volunteers, and underwent physical examination, blood chemistry and urinary analysis before and after one month of tea drinking. A three-day dietary record was taken before each physical examination. The tea drinkers showed a lower level of phosphatidylcholine hydroperoxide (PCOOH) and phosphatidyl-ethanolamine hydroperoxide (PEOOH) in the red blood cells and a significant reduction of 8-hydroxydeoxyguanine (8ohdG) in the urine compared to the controls.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed1999

Antimutagenic and anticarcinogenic activity of tea polyphenols.

Tea is the most popular beverage, consumed by over two thirds of the world's population. Tea is processed differently in different parts of the world to give green (20%), black (78%) or oolong tea (2%). Green tea is consumed mostly in Japan and China. The antimutagenic and anticarcinogenic activities of green tea are extensively examined. The chemical components of green and black tea are polyphenols, which include EC, ECG, EGC, EGCG and TFs. This article reviews the epidemiological and experimental studies on the antimutagenicity and anticarcinogenicity of tea extracts and tea polyphenols. In Japan, an epidemiological study showed an inverse relationship between habitual green tea drinking and the standardized mortality rates for cancer. Some cohort studies on Chanoyu (Japanese tea ceremony) women teachers also showed that their mortality ratio including deaths caused by malignant neoplasms were surprisingly low. The antimutagenic activity against various mutagens of tea extracts and polyphenols including ECG and EGCG has been demonstrated in microbial systems (Salmonella typhimurium and Escherichia coli), mammalian cell systems and in vivo animal tests. The anticarcinogenic activity of tea phenols has been shown in experimental animals such as rats and mice, in transplantable tumors, carcinogen-induced tumors in digestive organs, mammary glands, hepatocarcinomas, lung cancers, skin tumors, leukemia, tumor promotion and metastasis. The mechanisms of antimutagenesis and anticarcinogenesis of tea polyphenols suggest that the inhibition of tumors may be due to both extracellular and intracellular mechanisms including the modulation of metabolism, blocking or suppression, modulation of DNA replication and repair effects, promotion, inhibition of invasion and metastasis, and induction of novel mechanisms.

Animals↗
PubMed1995

Effect of different levels of an ascorbic acid and tea mixture on nonheme iron absorption from a typical Tunisian meal fed to healthy rats.

The aim of our study was to evaluate the bioavailability of iron from a typical Tunisian meal 'couscous' provided to healthy rats with or without appropriate mixtures of tea plus ascorbic acid and to search for the optimal amount of ascorbic acid able to overcome the inhibitory effect of tea prepared under realistic Tunisian circumstances. Our findings show that a tea decoction (100 mg/ml) reduced nonheme iron absorption from couscous by 50% (16.5 vs. 33.1%; p < 0.01). In contrast, administration of 20 mg ascorbic acid increased nonheme iron absorption from couscous by more than 100% (66.8 vs. 33.1%; p < 0.001). Administration of ascorbic acid (20 mg) in a tea decoction (100 mg/ml) completely counteracted the inhibiting effect of tea and significantly improved the nonheme iron absorption from couscous (34 vs. 33% in the control group; NS). The same effect was shown when 10 mg ascorbic acid was added to the tea decoction; however, 5 mg ascorbic acid was not able to overcome the inhibitory effect of tea on nonheme iron absorption from couscous (33.1 vs. 19.4%; p < 0.01). Our findings demonstrate that a molar ratio of ascorbic acid and tea equal or superior to 0.25 or 0.50 is necessary to overcome the inhibitory effect in rats of tea prepared under Tunisian circumstances. In relation to human nutrition, for Tunisians who regularly drink tea, we suggest a much greater amount of ascorbic acid than that normally recommended for normal subjects.

Absorption↗
PubMed1998

Consumption of tea and coffee and the risk of lung cancer in cigarette-smoking men: a case-control study in Uruguay.

This study investigated the effect of drinking tea or coffee on the lung cancer risk of male cigarette smokers in a case-control in Uruguay. Four hundred and twenty-seven lung cancer cases were frequency matched on age and residence with 428 hospitalized controls suffering from conditions unrelated to tobacco smoking and diet. Whereas coffee drinking had no effect on the lung cancer risk of the cigarette-smoking men in this study, black tea consumption decreased this risk. Heavy drinkers of tea (two or more cups of tea per day) were associated with a reduced risk of 0.34 (95% CI 0.14-0.84). This protective effect was more evident among Kreyberg I tumors (squamous cell and small cell) and among light smokers. Possible sources of bias and mechanisms of action are discussed.

Adult↗
PubMed2004

Detection and determination of reticuline and N-methylcoculaurine in the Annonaceae family using liquid chromatography-tandem mass spectrometry.

In Guadeloupe, the French West Indies, there is a high incidence of atypical parkinsonism or progressive supranuclear palsy, and all of the investigated patients had taken herbal tea or tropical fruits of the Annonaceae family. Local inhabitants consume the fruits, and also drink tea made from the leaves. In the present study, we used liquid chromatography-tandem mass spectrometry (LC/MS/MS) with multiple reaction monitoring (MRM) to detect low-molecular-weight neurotoxic benzylisoquinoline derivatives in the Annonaceae family. We detected reticuline and N-methylcoculaurine in every Annona muricata sample examined, except for pulp and seed. They were not detected in sweetsop fruits. Norreticuline was not detected in any sample. These three compounds were toxic to SH-SY5Y neuroblastoma cells and inhibited mitochondrial respiratory complex I. It is possible that uptake of the benzylisoquinoline derivatives reticuline and N-methylcoculaurine and their accumulation in the brain may be related to the pathogenesis of the local endemic disease.

Alkaloids↗
PubMed1999

Prevalence of nutritional anaemia among primary school girls in Riyadh City, Saudi Arabia.

The prevalence of iron deficiency anaemia was investigated among 1,210 school girls in Riyadh, Saudi Arabia. Anthropometric measurements were recorded. A dietary and socio-economic status questionnaire was administered and heamoglobin (Hb), serum iron and ferritin were estimated. Wasting and stunting is common among the 7- and 14-year-old girls. A total of 8.5% of children showed Hb level below 10 g/dL while 55.4% showed Hb level below 12 g/dL. It was found that 26.3% of the girls have serum iron below 10 mumol/dL while 16.1% of subsample of the girls showed serum ferritin level of less than 12 micrograms/dL. The most affected ones are those in the age group of 7-14 years old. The dietary questionnaire revealed that 16.5% of the girls did not take breakfast at home and depend on snacks offered in the school canteen which consist mostly of biscuits, chocolate bars, potato chips and carbonated cola drinks. No association between education of mother and father and breakfast consumption at home was detected. Tea drinking is common among these girls while fresh fruits and vegetable consumption is infrequent. Iron deficiency anaemia is highly prevalent among these schoolgirls which seriously affects the growth of 7- and 14-year-old girls. An in-depth investigation of the etiological factors of iron deficiency is urgently needed and meanwhile a suitable iron supplementation program is recommended.

Adolescent↗
PubMed1993

[Contents of aluminum and manganese in tea leaves and tea infusions].

We measured the contents of aluminum and manganese in tea leaves and tea infusions by means of various standardized infusion conditions, and by using flameless atomic absorption spectrophotometry, and investigated the influence of infusion conditions on the elution of aluminum and manganese into the tea infusions. Furthermore, we tried to estimate the daily intake of aluminum and manganese due to drinking tea infusions. The content of aluminum in tea leaves was 1420 micrograms/g in case of wulong tea, 576 micrograms/g in black tea, and 520 micrograms/g in green tea. The content of manganese was 1440 micrograms/g in the case of wulong tea, 670 micrograms/g in green tea, and 535 micrograms/g in black tea. The concentration of aluminum in tea infusions was 1.49-5.58 micrograms/ml in wulong tea, 0.90-4.92 micrograms/ml in green tea, and 0.64-4.35 micrograms/ml in black tea. The concentration of manganese was 1.75-6.67 micrograms/ml in green tea, 0.94-4.04 micrograms/ml in wulong tea, and 0.78-3.24 micrograms/ml in black tea. The ratio of the molar concentration of aluminum to that of manganese was 1-2:1 in tea leaves, and 1-5:1 in tea infusions. In the case of elevated-temperature infusion, increases of the concentrations of aluminum and manganese in tea infusions were recognized. By repeating infusion three times according to the standard method for ingredient analysis of food, 18-29% of the total content of aluminum in tea leaves was eluted, and 12-29% of the total content of manganese was eluted.(ABSTRACT TRUNCATED AT 250 WORDS)

Aluminum↗
PubMed1986

Protein conversion efficiencies of four test diets based on milk, two milk and tea treatments, and casein.

Milk consumption in 80 households in western Kenya averaged .25 to 1.00 L per family per day. Most of this milk was processed into a milk and tea beverage. Polyphenols, the major determinants of tea flavor and character, form soluble complexes with casein when black tea infusions are mixed with milk. Test diets were prepared from the following treatments: a) casein reference diet; b) milk, no tea leaves; c) milk added after heat treatment; and d) traditional Kenyan-style tea (i.e., milk and tea leaves heated together). Four groups of 10 male 21-day-old Sprague Dawley weanling rats were assembled and assigned to the test diets. Weight gain and protein intake (g/g) during a 28-d test period for the four diets were 1.94, 2.99, 2.93, and 2.77. The least significant difference test showed weight gain for protein intake was greater for rats on the milk-based diet and the diet with milk added after heating than for rats on the traditionally prepared milk and tea drink. Rats did most poorly when assigned to the casein reference diet. Modification of traditional Kenyan tea preparation practices (i.e., adding milk after tea leaves have been removed) might improve the nutritional value of the most popular milk product in western Kenya.

Animals↗
PubMed2001

Pharmacokinetics of gallic acid and its relative bioavailability from tea in healthy humans.

Gallic acid (GA), a food component that is especially abundant in tea, is an antimutagenic, anticarcinogenic and anti-inflammatory agent. We conducted a study using acidum gallicum tablets that contained 10% GA and 90% glucose and a black tea brew that contained 93% of its GA in free form to determine the pharmacokinetics and relative bioavailability of GA in healthy humans. After the administration of a single oral dose of acidum gallicum tablets or tea (each containing 0.3 mmol GA) to 10 volunteers, plasma and urine samples were collected over various time intervals. Concentrations of GA and its metabolite, 4-O-methylgallic acid (4OMGA), were determined, and the pharmacokinetic parameters were calculated. GA from both the tablets and tea was rapidly absorbed and eliminated with mean half-lives of 1.19 +/- 0.07 and 1.06 +/- 0.06 h and mean maximum concentrations of 1.83 +/- 0.16 and 2.09 +/- 0.22 micromol/L (plasma), respectively. After oral administration of the tablets and black tea, 36.4 +/- 4.5 and 39.6 +/- 5.1% of the GA dose were extracted in urine as GA and 4OMGA, respectively. The relative bioavailability of GA from tea compared with that from the tablets was 1.06 +/- 0.26, showing that GA is as available from drinking tea as it is from swallowing tablets of GA.

Adult↗
PubMed1998

Blood and urine levels of tea catechins after ingestion of different amounts of green tea by human volunteers.

The inhibitory activity of tea against tumorigenesis has been demonstrated in many animal models and has been suggested by some epidemiological studies. Such activity has generally been attributed to tea catechins. To understand the bioavailability of tea catechins in humans, we gave 18 individuals different amounts of green tea and measured the time-dependent plasma concentrations and urinary excretion of tea catechins. After taking 1.5, 3.0, and 4.5 g of decaffeinated green tea solids (dissolved in 500 ml of water), the maximum plasma concentration (Cmax) of (-)-epigallocatechin-3-gallate (EGCG) was 326 ng/ml, the Cmax of (-)-epigallocatechin (EGC) was 550 ng/ml, and the Cmax of (-)-epicatechin (EC) was 190 ng/ml. These Cmax values were observed at 1.4-2.4 h after ingestion of the tea preparation. When the dosage was increased from 1.5 to 3.0 g, the Cmax values increased 2.7-3.4-fold, but increasing the dose to 4.5 g did not increase the Cmax values significantly, which suggested a saturation phenomenon. The half-life of EGCG (5.0-5.5 h) seemed to be higher than the half-life of EGC or EC (2.5-3.4 h). EGC and EC, but not EGCG, were excreted in the urine. Over 90% of the total urinary EGC and EC was excreted within 8 h. When the tea dosage was increased, the amount of EGC and EC excretion seemed to increase, but a clear dose-response relationship was not observed. The present study provides basic pharmacokinetic parameters of green tea catechins in humans; these parameters may be used to estimate the levels of these compounds after drinking tea.

Adult↗