Tea In Rats Research Articles

Investigating the Hepatic Response to Orlistat and White Tea in Rats on a High-Fat Diet.

High-fat diets have detrimental health impacts that increase the likelihood of developing obesity and metabolic syndrome. This study aimed to examine the potential antioxidant and anti-inflammatory effects of orlistat and white tea in rats fed a high-fat diet. Thirty-two rats were randomized into four groups: control (standard diet), HFD (high-fat diet), HFD+Orlistat (high-fat diet+orlistat), and HFD+WT (high-fat diet+white tea extract). A significant increase in malondialdehyde (MDA) levels and a decrease in total thiol (TT) levels were detected in the HFD group (p < 0.001). On the other hand, a decrease in the MDA level (p < 0.001) and an increase in the TT level were observed in the orlistat and white tea groups compared with those in the HFD group (p < 0.001). Histopathological examinations revealed that, compared with the HFD alone, orlistat and white tea reduced fat accumulation, prevented degenerative changes in hepatocytes, and decreased the histopathological damage score (p = 0.001). Immunohistochemical examinations of nuclear factor-kappa B (NF-kB/p65) revealed that compared with the HFD, orlistat and white tea reduced immunopositivity (p = 0.001). White tea decreases lipid peroxidation and oxidative stress. Both white tea and orlistat decreased fat formation and inflammation in the liver and regulated inflammation by reducing Nf-kB positivity. Nevertheless, further research is needed to assess their impact on human subjects.

Brewing Health Benefits: A Comparative Study Of Black, Herbal, And Green Tea On Rat Physiology

This study compared the physiological effects of black, herbal, and green tea in rats to determine prospective health advantages. Animals were divided into eight groups of six male rats each. In the morning and evening, the negative control group was intubated with 1ml of distilled water, with rat chow and water. The remaining six groups got each type of tea (black, herbal, and green) in the morning and evening for 14 days while physiological data were recorded. Green tea showed the most significant lipid profile and liver function improvement among the three tea varieties. The findings imply that all three tea varieties may have health advantages, particularly in enhancing liver health and lipid profiles. The highest impacts on lipid profile and body weight reduction were specifically shown with green tea.

Neuroprotective Effect of White Nelumbo nucifera Gaertn. Petal Tea in Rats Poisoned with Mancozeb.

Nelumbo nucifera Gaertn. (N. nucifera) tea is used as food and folk medicine to reduce toxicity in Southeast Asia. Mancozeb (Mz) is used for controlling fungi in agriculture and contains heavy metals. This study aimed to examine the effect of white N. nucifera petal tea on cognitive behavior, hippocampus histology, oxidative stress, and amino acid metabolism in rats poisoned with mancozeb. Seventy-two male Wistar rats were divided into nine groups (n = 8 in each). Y-maze spontaneous alternation test was used to assess cognitive behavior, and amino acid metabolism was investigated by nuclear magnetic resonance spectroscopy (1H-NMR) from blood. There was a significant increase in relative brain weight in the Mz co-administered with the highest dose (2.20 mg/kg bw) of white N. nucifera group. The levels of tryptophan, kynurenine, picolinic acid, and serotonin in blood showed a significant decrease in the Mz group and a significant increase in the Mz co-administered with low dose (0.55 mg/kg bw) of white N. nucifera group. However, there was no significant difference in cognitive behavior, hippocampus histology, oxidative stress, and corticosterone. This study demonstrated that a low dose of white N. nucifera petal tea has a neuroprotective effect against mancozeb.

Safety evaluation and hypolipidemic effect of aqueous-ethanol and hot-water extracts from E Se tea in rats

E Se tea, processed by the fresh leaves of Malus toringoides (Rehd.) Hughes, is a traditional herbal tea with various human benefits. The present study was aimed to evaluate the toxicity and hypolipidemic effect of aqueous-ethanol extract (EE) and hot-water extract (WE) from E Se tea. Eight main chemical constituents in EE and WE were respectively identified and quantified by UHPLC-HRMS/MS. EE is rich in TPC and TFC, while WE had higher TPS content. Both EE and WE exhibited strong antioxidant activity with no significant difference. The acute toxicity study revealed that the LD50 values were higher than 5000 mg/kg, while both WE and EE had no significant adverse effect in rats by subacute toxicity assay. However, the triglyceride (TG) content in experiment groups (male) and highest doses groups (female) significantly decreased. Furthermore, the hypolipidemic effect of WE and EE were performed on high fat diet induced hyperlipidemic rats. The result exhibited that either WE or EE could effectively regulate lipid droplet accumulation in liver, and reduce the adipocyte size. These results demonstrated that these two extracts from E Se tea could be regarded as a potential functional dietary supplement in preventing and treating diet induced metabolic diseases.

Pectin Influences the Absorption and Metabolism of Polyphenols from Blackcurrant and Green Tea in Rats.

Consumption of polyphenols and dietary fiber as part of a normal diet is beneficial to human health. In this study, we examined whether different amounts of dietary soluble fiber (pectin) affect the absorption and metabolism of polyphenols from blackcurrant and green tea in rats. After 28 days, the rats fed blackcurrant and green tea with pectin (4 or 8%) had significantly lower body weight gain and food intake compared to the rats fed a control diet. Rats fed a blackcurrant and green tea diet with 8% pectin had significantly higher fecal nitrogen output and lower protein digestibility. No polyphenols were observed in the urine, feces and plasma of rats fed the control diet. Parent catechins and flavonols were absent in urine obtained from all diet groups. Gallocatechin glucuronide was only observed in the plasma of rats fed the blackcurrant and green tea diet without pectin. Meanwhile, epicatechin and catechin gallate were present in the feces of rats fed a blackcurrant and green tea diet with and without 4% pectin. Pectin (4 or 8%) added to the blackcurrant and green tea diet increased the plasma antioxidant capacity in rats. Inclusion of pectin in the diet altered the host absorption and metabolism of polyphenols from blackcurrant and green tea.

Evaluation of Acute and Subacute Toxicity of Two Different Extracts from Que Zui Tea in Rats

The buds of Vaccinium dunalianum Wight (VD) are widely used in Yunnan as herbal tea [Que Zui Tea (QT)] and herb. However, the security and toxicity of QT have not been determined yet. The aim of this study is to evaluate the acute and subacute-toxicity of hot water (QTW) and aqueous-ethanol (QTE) extracts of QT. Acute-toxicity studies of QTW and QTE revealed no signs of related to treatment, indicating that median-lethal-dose (LD50) values of QTW and QTE is surpass 5000 mg/kg. The results of subacutetoxicity studies of QTW and QTE showed no significant side reaction of all doses the two extracts. The levels of Lymphocyte (LYM) and percentage of lymphocytes (LYM%) significantly decreased, and percentage of granulocytes (GRA%) increased in rats that received these two extracts at doses greater than 1250 mg/kg/day. However, the 1250 and 2500 mg/kg/day QTW and QTE did not trigger any pathological changes in body weight or organ tissue, so partial changes in blood parameters were considered as minor symptoms. Therefore, the present results demonstrated that the two extracts are safe at 2500 mg/kg/day or at lower doses.

Hypoglycemic and hypolipidemic activities of phlorizin from Lithocarpus polystachyus Rehd in diabetes rats.

The objective of this study was to investigate the hypoglycemic and hypolipidemic effects of phlorizin on sweet tea in rats with diabetes. Diabetic rat model was established by feeding with HFD (high‐fat diet) and then treating with intraperitoneal injection of STZ (streptozocin). The experiments were divided into therapeutic and preventive experiments. In both experiments, rats were divided into normal, diabetic control, positive control, and phlorizin groups. Symptoms of diabetes, fasting blood glucose (FBG) levels, serum lipid parameters, and pathological changes in the pancreas and liver were evaluated. It was found that the symptoms of diabetes were improved by phlorizin treatment. In addition, phlorizin could decrease FBG, improve serum lipid levels, protect against damaged pancreas islet, and decrease fat deposition in hepatic cells. These effects of phlorizin can be shown only attain to a certain dosage. It can be concluded that phlorizin has the therapeutic and preventive effects on hyperlipidemia and hyperglycemia in diabetes rats.

The Effect of Different Doses of Green Tea Extract on Hematological and Biochemical Parameters in Adult Male Rats

This investigates the effects of various concentrations of continuous drinking of green tea in rats. (24) male rats are randomly categorized into four groups: control, which does not receive green tea, GTE5, GTE10 and GTE20 (receive 5g, 10g and 20g GTE, respectively). In hematological parameters analysis, there are no significant variation (p>0.05) in the RBC, MCHC and platelet among all groups. Furthermore, Control group presented a considerable decrease (p <0.05) in HB, HTC, MCV and MCH as compared with GTE5, GTE10 and GTE20. The biochemical analysis, control and GTE5 groups had high significant decrease (p<0.05) in glucose level as compared with GTE10 and GTE20 groups. Analysis of albumin and globulin, control and GTE5 groups had a significant decrease (p<0.05) higher than that of GTE10 and GTE20 groups. On the other hand, GTE20 group revealed a highly significant increase variation (p<0.05) in total protein than the control, GTE5 and GTE10 groups. In the control group showed a significant increase (p <0.05) in values of AST, ALT and ALK as compared with other groups. Therefore, it is recommended that using green tea for a long period leads to inhibition of the free oxygen radical damages in the liver and erythrocyte.

Subchronic toxicity of huanghuali tea in rats

Objective To assess subchronic toxicity of huanghuali ( Dalbergia odorifera T. Chen ) tea in rats. Methods A ninety-day feeding experiment was performed in 140 specific pathogen free Sprague-Dawley (SD) rats according to the Food Safety Toxicology Evaluation Procedures and Methods – 2015 Edition. Results During the experiment, all the rats were generally in good condition and no death was observed. Compared with those of the control rats, there was no significant difference in weekly body weight, food intake and food utilization rate of final phase, hematology and serum biochemical indexes, organ weight and organ/body weight ratio in rats of all the dose groups ( P > 0.05). No remarkable changes were observed in urinary routine indicators, eye examination and gross anatomy, and histopathological examinations. Conclusion Huanghuali tea shows no obvious toxicity, with a no observed adverse effect level (NOAEL) of 22.22 g/kg·bw, in rats. 【摘 要】 目的 探讨黄花梨茶对大鼠的亚慢性毒性作用。 方法 参照 2015 版《食品安全性毒理学评价程序和方法》中的 90 d 喂养试验方法对黄花梨茶的亚慢性毒性进行分析。 结果 试验观察期间大鼠一般状态良好，无死亡；与对照组比较，各剂量黄花梨茶组大鼠体重、进食量和食物利用率、动物血液学和血清生化指标以及脏器重量及脏器/体重比值无明显变化，差异均无统计学意义（ P > 0.05）；尿常规指标、眼部检查及大体解剖和组织病理检查未见明显与受试物有关的异常改变。 结论 黄花梨茶对大鼠无明显亚慢性毒性作用，最大未观察到有害作用剂量（NOAEL）为 22.22 g/kg。

Cholesterol/HDL-c ratio lowering effect of green tea in rats exposed to depot medroxiprogesterone acetate

Objective: This study aimed to investigate whether an extract of green tea is able to decrease low density lipoprotein-cholesterol (LDL-c) and increase high density lipoprotein (HDL)-c in rats exposed to depot medroxyprogesterone acetate (DMPA). Methods: Twenty five female Wistar rats were divided into five groups (n = 5 each): (1) untreated negative control; (2) positive control which received DMPA only; (3) DMPA plus green tea extract at the dose of 10.8 mg/kg/day; (4) DMPA plus green tea extract at the dose of 21.6 mg/kg/day; (5) and DMPA plus green tea extract at the dose of 43.2 mg/kg/day. The treatment with green tea was performed for four weeks. Serum lipid profile and atherogenic index were analyzed by automated enzymatic technique Results: DMPA significantly changed the serum lipid profile marked by decreased HDL, increased LDL and cholesterol/HDL-c ratio compared with the untreated group. The increase in LDL was significantly attenuated by all treatment doses of of green tea. Similarly, the decrease in HDL level was significantly attenuated by all doses of the extract. On the other hand, increased levels of cholesterol/HDL-c ratio in the DMPA group was significantly reduced by lowest and highest doses of green tea extract. Conclusion: Green tea extract inhibits the increase in LDL-c and cholesterol/HDL-c ratio induced by DMPA. This may provide a natural therapeutic alternative for normalizing the lipid profile found in subjects exposed to DMPA.

Major flavonoid constituents and short-term effects of Chun Mee tea in rats

Chun Mee tea is a kind of green tea produced in China mainly for export purposes. Foam quantity is usually used as an index for evaluating the quality of Chun Mee tea. In the current study, we compared the concentrations of total saponin and flavonoids between foamy and low-foam Chun Mee tea. Our research confirmed that the total saponin and O-glycosylated flavonoid concentrations were related to the foam quantity of Chun Mee teas. We also studied the short-term safety effects of extract supplementation with foamy and low-foam Chun Mee tea in rats by routine blood tests and analysis of liver and kidney function, and blood lipids. Our results showed that both types of tea extract supplementations did not cause any observable adverse effects or impair either liver or kidney function. Additionally, this study confirmed the beneficial effects of Chun Mee tea extract supplementation on the decrease of total plasma cholesterol.

Hypotriglyceridemic Potential of Fermented Mixed Tea Made with Third-Crop Green Tea leaves and Camellia (Camellia japonica) Leaves in Sprague–Dawley Rats

Fermented mixed tea made with third-crop green tea leaves and camellia leaves by a tea-rolling process has been developed. The objective of this study was to investigate hypotriglyceridemic potential of the mixed tea in rats. The mixed tea contained theasinensins and theaflavins. Rats fed the mixed tea extract at the level of 1% exerted significantly lower body weight and adipose tissue weight compared to animals fed third-crop green tea or camellia tea extract alone for 4 weeks. Serum and hepatic triglyceride was significantly and dose-dependently decreased by the mixed tea. This decrease was associated with lowered lipogenic enzyme activities in the liver. Furthermore, an oral administration of 4 or 8% of the mixed tea extract followed by fat emulsion suppressed the increment of serum triglyceride level. These results suggest that the mixed tea has hypotriglyceridemic action, partially via delaying triglyceride absorption in the small intestine and repressing hepatic lipogenic enzymes.

Effect of pu‐erh tea on body fat and lipid profiles in rats with diet‐induced obesity

The antiobesity and antihyperlipidaemic effects of pu-erh tea in rats with high fat diet (HFD)-induced obesity were investigated. Male Sprague-Dawley rats were randomly divided into five groups and fed varying diets for an 8-week period: control diet, HFD, and HFD supplemented with low, moderate or high doses of pu-erh tea extract (0.5 g, 2 g and 4 g/kg BW/day, respectively). Pu-erh tea significantly reduced the total body weight and the weight of various adipose pads. Pu-erh tea administration also significantly lowered plasma total cholesterol, triglyceride concentrations and low-density lipoprotein-cholesterol levels in rats with HFD-induced obesity, but did not affect high-density lipoprotein-cholesterol levels. Moreover, pu-erh tea significantly increased lipoprotein lipase, hepatic lipase and hormone-sensitive lipase activities in epididymal fat tissue in rats with HFD-induced obesity. Analysis of real-time reverse transcription-polymerase chain reaction results indicated that pu-erh tea significantly enhanced mRNA levels of hormone-sensitive lipase in rats with HFD-induced obesity. These results suggest that pu-erh tea attenuated visceral fat accumulation and improved hyperlipidemia in a rat model of HFD-induced obesity.

Review Article: Does kombucha tea attenuate the hepato-nepherotoxicity induced by a certain environmental pollutant?

Trichloroethylene (TCE) may induce oxidative stress which generates free radicals and alters antioxidants or oxygen-free radical scavenging enzymes. The aim of this study was to investigate the protective role of oral administration of kombucha tea in rats with TCE as an environmental pollutant. Methods: Twenty male albino rats were divided into four groups: the control group treated with vehicle, Kombucha (KT)-treated group, TCE-treated group and KT/TCE-treated group. Liver and kidney lipid peroxidation, glutathione content, nitric oxide (NO) and total blood free radical concentrations were evaluated. Serum urea, creatinine level, gamma-glutamyl transferase (GGTP) and lactate dehydrogenase (LDH) activities were also measured. Results: TCE administration increased the malondialhyde (MDA) and NO contents in liver and kidney, urea and creatinine concentrations in serum, total free radical level in blood and GGTP and LDH activities in serum, whereas it decreased the glutathione (GSH) level in liver and kidney homogenate. KT administration significantly improved lipid peroxidation and oxidative stress induced by TCE. Conclusion: The present study indicates that Kombucha may repair damage caused by environmental pollutants such as TCE and may be beneficial to people who deal with these chemicals.

Studies of anti‐inflammatory effects of Rooibos tea in rats

Rooibos tea is known to be caffeine free with abundant flavonoids. Aspalathin and nothofagin, the main flavonoids contained in Rooibos tea, have stronger anti-oxidative activity than other flavonoids. As oxidative stress can induce inflammation, the anti-inflammatory effects of Rooibos tea were investigated using a rat colitis model. Seven-week-old Wister rats were divided into two groups: one group given Rooibos tea, and one given water. After four weeks of breeding, serum superoxide dismutase (SOD) levels were determined using the Electron Spin Resonance analysis. Urine 8-hydroxy-2'-deoxyguanosine (8-OHdG) concentrations were also determined as reflections of DNA damage using enzyme-linked immunosorbent assay. Furthermore, rats were administrated dextran sodium sulfate (DSS), which is known to induce colitis in rodents, with or without Rooibos tea to evaluate its anti-inflammatory activity. Clinical symptoms, hemoglobin, serum iron and SOD levels were compared between the groups. There were no significant differences in bodyweight gain or laboratory data between the groups. The serum SOD levels were significantly increased, and urine 8-hydroxy-2'-deoxyguanosine levels were significantly decreased in the Rooibos group compared with the controls (P < 0.05 in each). After DSS administration, the serum SOD levels were significantly higher in the Rooibos group compared to the controls (P < 0.05). As a result, a decreased hemoglobin level, observed in the control group, was prevented in the Rooibos group after the DSS challenge. Rooibos tea may prevent DNA damage and inflammation by its anti-oxidative activity in vivo. As Rooibos tea is free from caffeine, routine intake may be safe and useful in reducing oxidative stress in children.

Green Tea Maintains Antioxidative Defense Enzyme Activities and Protects Against Lipid Peroxidation in Rat Gastrocnemius Muscles After Aerobic Exercise

This study investigated the effects of green tea on the muscle antioxidative defense system in the white & red gastrocnemius muscles of rats after aerobic exercise. Male Sprague-Dawley rats weighing 150±10 g were randomly assigned to a control group, non-exercise with green tea group (G group), and exercise training group. The exercise training group was then further classified as the training (T) group and training with green tea (TG) group, the latter of which was supplemented with green tea in the drinking water during the experimental period. The rats in the exercise training groups (T and TG) were subjected to aerobic exercise on a treadmill 30 min/day at a speed of 28 m/min (7% incline) 5 days/week, while the other groups (control and G group) were cage confined for 4 weeks. Thereafter, the rats were sacrificed with an injected overdose of pentobarbital just after running. In the white muscle, the xanthine oxidase (XOD) activities were 71% higher in the T group compared to control group, whereas the TG group had the same activity as the control group. The XOD activities in the red gastrocnemius muscle exhibited the same tendency as in the white muscle. The superoxide dismutase (SOD) activity in the white muscle was lower in the T group compared with the control group, yet significantly higher in the TG group compared with the T group. The SOD activities in the red gastrocnemius muscle exhibited the same tendency as in the white gastrocnemius muscle. The glutathione peroxidase (GSHpx) activities in the white & red gastrocnemius muscles were 43% lower in the T group compared with the control group, yet the activities in the TG group remained at control levels. The glutathione S-transferase (GST) activity in the white muscle was not significantly different among any of the three groups, but in the red gastrocnemius muscle, the TG group had the same activity as in the control group. The thiobarbituric acid reactive substance (TBARS) contents in the white & red gastrocnemius muscles were higher in the T group than in the control but the control and TG groups had the same concentrations of TBARS. In conclusion, the supplementation of green tea in rats subjected to aerobic exercise was found to reduce the peroxidation of muscle lipids by enhancing the antioxidative defense mechanism.

Green tea reduces body fat accretion caused by high-fat diet in rats through β-adrenoceptor activation of thermogenesis in brown adipose tissue

The aim of the present study was to investigate body fat-suppressive effects of green tea in rats fed on a high-fat diet and to determine whether the effect is associated with β-adrenoceptor activation of thermogenesis in brown adipose tissue. Feeding a high-fat diet containing water extract of green tea at the concentration of 20g/kg diet prevented the increase in body fat gain caused by high-fat diet without affecting energy intake. Energy expenditure was increased by green tea extract which was associated with an increase in protein content of interscapular brown adipose tissue. The simultaneous administration of the β-adrenoceptor antagonist propranolol(500 mg/kg diet) inhibited the body fat-suppressive effect of green tea extract. Propranolol also prevented the increase in protein content of interscapular brown adipose tissue caused by green tea extract. Digestibility was slightly reduced by green tea extract and this effect was not affected by propranolol. Therefore it appeared that green tea exerts potent body fat-suppressive effects in rats fed on a high-fat diet and the effect was resulted in part from reduction in digestibility and to much greater extent from increase in brown adipose tissue thermogenesis through β-adrenoceptor activation.

Effect of fertilization on selenium content of tea and the nutritional function of Se-enriched tea in rats

The present study examined the effect of fertilization with sodium selenite on the selenium content of tea and the nutritional function of Se-enriched tea. Selenium content of tea leaves was increased up to 0.36 μg g−1 by the application of sodium selenite to soil at 0.5 and 1.0 kg Se ha−1. Application by a Se-enriched organic manure at a rate of 0.5 kg Se ha−1 provided a higher biological availability of selenium for plant uptake compared with a similar amount of sodium selenite. Foliar spray of sodium selenite at 50–100 g Se ha−1 increased the selenium content to 0.32–1.45 μg g−1 in tea leaves sampled at the 8–26 days after spraying. Selenium content in the blood and liver, glutathione peroxidase activity in blood of rats were significantly enhanced by feeding of an extracted solution of Se-enriched tea leaves and sodium selenite. Glutathione peroxidase activity in liver of rats fed with Se-enriched tea was higher than that fed with sodium selenite, indicating that the selenium in Se-enriched tea leaves is a more effective Se source than sodium selenite. Increasing the Se level in food products through the application of a selenium fertilizer is a safe, effective and feasible means of increasing the selenium intake of human and animals in low selenium areas of China.

Physiological function of Se‐enriched tea fertilised with sodium selenite and naturally high‐Se tea in rats

In order to increase food selenium (Se) content, Se-enriched tea was produced by fertilising with sodium selenite in low-Se soil. Five groups of rats were fed a low-Se diet supplemented with either water (Se-deficient), sodium selenite or an aqueous extraction of low-Se tea, Se-enriched tea or naturally high-Se tea. The chemical form of Se in Se-enriched tea and the physiological function in rats fed the different Se sources were determined after 8 weeks. The results showed that organic Se accounted for 80% or more of the Se in Se-enriched tea fertilised with sodium selenite and naturally high-Se tea, but no significant differences in the proportion of organic Se and protein Se were found between Se-enriched tea and naturally high-Se tea. The Se biological utilisation rates were 65.41, 68.05 and 70.49% for sodium selenite, Se-enriched tea and naturally high-Se tea respectively. The Se content of blood and liver and the glutathione peroxidase (GSH-Px) activity were significantly increased by feeding Se-enriched tea and sodium selenite compared with low-Se tea, but a more efficient increase in liver GSH-Px activity was obtained with Se-enriched tea than with sodium selenite. No significant differences were found between Se-enriched tea fertilised with sodium selenite and naturally high-Se tea, which proved that the biological effectiveness of Se in Se-enriched tea was higher than that of sodium selenite in increasing liver GSH-Px activity. Se-enriched tea fertilised with sodium selenite in low-Se soil gave the same biological function as naturally high-Se tea. Therefore Se-enriched tea is a safe and effective means of increasing the Se intake of both humans and animals in low-Se areas. © 2000 Society of Chemical Industry

Physiological function of Se-enriched tea fertilised with sodium selenite and naturally high-Se tea in rats

In order to increase food selenium (Se) content, Se-enriched tea was produced by fertilising with sodium selenite in low-Se soil. Five groups of rats were fed a low-Se diet supplemented with either water (Se-deficient), sodium selenite or an aqueous extraction of low-Se tea, Se-enriched tea or naturally high-Se tea. The chemical form of Se in Se-enriched tea and the physiological function in rats fed the different Se sources were determined after 8 weeks. The results showed that organic Se accounted for 80% or more of the Se in Se-enriched tea fertilised with sodium selenite and naturally high-Se tea, but no significant differences in the proportion of organic Se and protein Se were found between Se-enriched tea and naturally high-Se tea. The Se biological utilisation rates were 65.41, 68.05 and 70.49% for sodium selenite, Se-enriched tea and naturally high-Se tea respectively. The Se content of blood and liver and the glutathione peroxidase (GSH-Px) activity were significantly increased by feeding Se-enriched tea and sodium selenite compared with low-Se tea, but a more efficient increase in liver GSH-Px activity was obtained with Se-enriched tea than with sodium selenite. No significant differences were found between Se-enriched tea fertilised with sodium selenite and naturally high-Se tea, which proved that the biological effectiveness of Se in Se-enriched tea was higher than that of sodium selenite in increasing liver GSH-Px activity. Se-enriched tea fertilised with sodium selenite in low-Se soil gave the same biological function as naturally high-Se tea. Therefore Se-enriched tea is a safe and effective means of increasing the Se intake of both humans and animals in low-Se areas. © 2000 Society of Chemical Industry