Table 4.
Health functions of tea in clinical trials.
| Subjects | Ingredients | Dosages | Health Functions | Mechanisms | References |
|---|---|---|---|---|---|
| 60 male sprinters | Green tea extract | 2 capsules × times/d, 2 × 4 w, with a 4-week washout period | Antioxidation | Prevent oxidative stress, by increasing total antioxidant capacity and decreasing MDA level of blood plasma. | [85] |
| 60 mildly hyper-cholesterolemic subjects | Catechin- enriched green and oolong tea | 2 × 300 mL/d, 12 w | Antioxidation | Improve GSH, SOD, CAT, GPx, and GR, and decrease lipid peroxidation. | [87] |
| 32 participants | Benifuuki and Yabukita green tea | 3 cups/d, 2 w | Antioxidation | Protect against cutaneous oxidative stress, by increasing the radical scavenging activity of the skin. | [86] |
| 68 SLE patients | Green tea extract | 1000 mg/2 capsules/d, 12 w | Anti-inflammation | Improve the SLE disease as well as the corresponding vitality and general health. | [94] |
| 45 male soldiers | Green tea | 12 g tea leaves/d | Anti-inflammation | Decrease plasma levels of IL-6 and NF-κB in soldiers with sleep deprivation. | [95] |
| 9 well-trained male cyclists | Green tea and carbohydrate | Acute ingestion | Anti-inflammation | Did not evidently improve inflammatory biomarkers during sprint cycling in athletes in comparison to carbohydrates. | [96] |
| 16 tobacco smokers | Green tea | 5 × 1 cup/d, 4 w | Anticancer | Reduce the risk of oral carcinogenesis, by modulating oral bacteria. | [110] |
| 70 Algerian prostate cancer patients and 120 age-matched healthy subjects | Green tea | 5 cups/2 g tea leaves/d, 6 m | Anticancer | Prevent prostate cancer initiation or delay its progression. | [111] |
| 60 high-grade prostate intraepithelial neoplasia patients | Green tea catechins | 600 mg/d, 6 and 12 m | Anticancer | Show a non-significant improvement in lower urinary tract symptoms and a better quality of life with very limited adverse effects. | [112] |
| 20 obese prehypertensive women | Green tea extract | 500 mg/3 capsules/d, 4 w | Cardiovascular-protection | Reduce blood pressure. | [135] |
| 20 healthy participants | Black tea | 200 mL/d, 1 w | Cardiovascular-protection | Enhance the cutaneous vascular response to gradual local heating to 42 °C, by activating endothelium-derived chemical mediators like NO. | [136] |
| 19 hypertensive patients | Black tea | With 150 mg polyphenols, twice/d, 8 d | Cardiovascular-protection | Protect blood vessels, by augmenting the amount of circulating angiogenic cells and blocking endothelial dysfunction. | [137] |
| 30 healthy male smokers | Green tea catechins | 580 mg/d, 2 w | Cardiovascular-protection | Improve human forearm endothelial dysfunction, and anti-atherosclerosis. | [138] |
| 50 healthy men | Green tea | equivalent to 200 mg EGCG/d | Cardiovascular-protection | Improve the endothelial function in humans in terms of flow-mediated dilation. | [139] |
| 936 postmenopausal women | Green tea extracts | 1315 mg catechins/4 capsules/d, 12 m | Cardiovascular-protection | Reduce blood TC and LDL-C levels, particularly in subjects with increased baseline TC level. | [141] |
| 99 mild hyper-cholesterolemia subjects | Functional black tea | with 2 g phytosterols, once/d, 4 w | Cardiovascular-protection | Reduce the TC, LDL-C, and apolipoprotein B levels, as well as oxidative stress index, increase adiponectin and tissue-plasminogen activator, and improve total antioxidant status. | [142] |
| 57 borderline hypercholesterolemic individuals | Black tea | 5 cups/d, 4 w | Cardiovascular-protection | Show no significant alteration on the lipid profile. | [143] |
| 30 T2DM patients | Black tea | 1 or 3 cups (200 or 600 mL)/d, 12 w | Anti-diabetes | Reduce HbA1c level and help to decrease the risk of suffering from TD2M. | [150] |
| 15 healthy subjects | Green tea | 400 mL/visit, 5 visits with a two-week washout period | Anti-diabetes | Suppress postprandial plasma glucose and insulin concentration. | [152] |
| 35 diabetic subjects | Green tea extract | 1120 mg/d, 10 and 20 w | Anti-diabetes | Improve glycemic control and prevent osteoporosis in diabetic patients | [153] |
| 102 women with central obesity | Green tea extracts | 856.8 mg/d, 12 w | Anti-obesity | Reduce body weight, waist circumference, and plasma TC and LDL levels, probably by inhibiting ghrelin secretion and increasing adiponectin levels. | [161] |
| 50 overweight women | Mixture of extracts | 125 mg green tea, 25 mg capsaicin, and 50 mg ginger extracts/d, 8 w | Anti-obesity | Reduce the weight, BMI, plasma GSH level, and insulin metabolism markers. | [162] |
| 30 non-athlete overweight females | green tea | 500 mg/3 tablets/d with high- intensity interval training, 10 w | Anti-obesity | Reduce body weight, BMI, and the undesirable consequence of overweight, by augmenting the levels of SIRT-1 and PPAR γ co-activator 1-α. | [164] |
| 48 overweight males | Green tea extracts | 250 mg/3 capsules/d, with interval sprinting exercise, 12 w | Anti-obesity | Decrease body and abdominal fat, and increase total lean mass in overweight males | [165] |
| 80 participants with NAFLD | Green tea extract | 500 mg/d, 90 d | Hepato- protection | Decrease the levels of liver enzymes including ALT, AST, and ALP | [177] |
| 60 mildly hypercholesterolemic subjects | Catechin- enriched green and oolong teas | 2 × 300 mL/d, 12 w | Hepato- protection | Decrease body weight, BMI, fat, lipid peroxidation, and lipid profiles (TG, TC, LDL-C, and HDL-C), and improve GSH, SOD, CAT, GPX, and GR in the liver. | [87] |
Notes: ALP, alkaline phosphatase; ALT, alanine aminotransferase; AST, aspartate transaminase; BMI, body mass index; CAT, catalase; GPx, glutathione peroxidase; GR, glutathione reductase; GSH, reduced glutathione; HbA1c, glycated hemoglobin A1C; HDL-C, high-density lipoprotein-cholesterol; IL, interleukins; LDL-C, low-density lipoprotein-cholesterol; MDA, malonaldehyde; NF-κB, nuclear factor-κB; PPAR γ, peroxisome proliferator-activated receptor γ; SIRT1, sirtuin 1; SLE, systemic lupus erythematosus; SOD, superoxide dismutase; T2DM, type II diabetes mellitus; TC, total cholesterol; TG, triglyceride.