Doc:Tea/Health
| Tea Top | Exotic teas | Production/Consumption | Health |
Contents |
Tea and Human Health
Cancer
None of the large-scale epidemiological studies found a significant association of tea intake with a lower risk of cancer[1]. However, many case-control studies and cross-sectional studies (up to several hundreds people) show a decrease of the risk of cancer.
- Breast cancer 乳がん
- Two prospective studies with 35,004 women [2] → no association
- Gastrointestinal cancer 胃腸がん
- Bladder cancer 膀胱がん
- Prospective cohort 14873 men and 23667 women [3] → no association
- Cancer incidence がん
- Prospective study 38540 people [3] → no association
- References
- ↑ Borrelli F, Capasso R et al. (2004) "Systematic review: green tea and gastrointestinal cancer risk" Aliment Pharmacol Ther 19:497-510 PMID 14987318
- ↑ Suzuki Y, Tsubono Y et al. (2004) "Green tea and the risk of breast cancer: pooled analysis of two prospective studies in Japan" Br J Cancer 90:1361-1363 PMID 15054454
- ↑ 3.0 3.1 3.2 Nagano J, Kono S et al. (2001) "A prospective study of green tea consumption and cancer incidence, Hiroshima and Nagasaki (Japan)" Cancer Causes Control 12:501-508 PMID 11519758
- ↑ Tsubono Y, Nishino Y et al. (2001) "Green tea and the risk of gastric cancer in Japan" New Engl J Med 344:632-636 PMID 11228277
- ↑ Hoshiyama Y, Kawaguchi T et al. (2002) "A prospective study of stomach cancer death in relation to green tea consumption in Japan" Br J Cancer 87:309-313 PMID 12177800
- ↑ Fujino Y, tamakoshi A et al. (2002) "Prospective study of educational background and stomach cancer in Japan" Prev Med 35:121-127 PMID 12200096
Cardiovascular Disease (CVD)
It is often believed that (oolong) tea possesses hypotensive effects. After Hertog MG et al. [1], flavonoid intakes have been reported to inversely associated with CVDs. In 2008, Hooper et al. performed a comprehensive review of reliable 133 flavonoid trials [2], and concluded that
- flavanol-rich cocoa reduces blood pressure by 6 (systolic) and 3 (diastolic) mm Hg,
- soy protein, which is rich in isoflavones, reduces LDL cholesterol by 0.2 mmol/L,
- black tea acutely (not chronic) raises blood pressure by 6 (systolic) and 3 (diastolic) mm Hg, and
- chocolate acutely (not chronic) increases flow-mediated dilation (FMD) by 4%.
At least, intake of cocoa and soy (not tea!) provide evidence for short-term beneficial effects on CVD. However, it remains unclear whether the effects can be attributed to the specific flavonoid species [3]. A large scale cohort study (34789 men) found no association with flavonoids and CVD [4] [5].
- ↑ Hertog MG, Feskens EJ (1993) "Dietary antioxidant flavonoids and risk of coronary heart disease: the Zutphen Elderly Study" Lancet 342(8878):1007-1011 PMID 8105262
- ↑ Hooper L, Kroon PA, Rimm EB, et al. (2008) "Flavonoids, flavonoid-rich foods, and cardiovascular risk: a meta-analysis of randomized controlled trials" Am J Clin Nutr 88:38–50 PMID 18614722
- ↑ Geleijnse JM, Hollman PCH (2008) "Flavonoids and cardiovascular health: which compounds, what mechanisms?" Am J Clin Nutr 88:12-13 PMID 18614717
- ↑ Rimm EB, Katan MB (1996) "Relation between intake of flavonoids and risk for coronary heart disease in male health professionals" Ann Intern Med 125(5):384-389 PMID 8702089
- ↑ Huxley RR, Neil HA (2003) "The relation between dietary flavonol intake and coronary heart disease mortality: a meta-analysis of prospective cohort studies" Eur J Clin Nutr 57:904–908 PMID 12879084
Hypercholesterolemia
In many animal studies, usually rats, various tea suppresses cholesterol levels. Catechins are considered to account for the hypocholesterolemic effect.
- Lower plasma triacylglycerols, cholesterol, and low-density lipoprotein (LDL) cholesterol in experimental Sprague-Dawley rats [1].
- Lower serum and liver cholesterols, but not HDL-cholesterol and triglyceride levels in rats. [2]
- ↑ Kuo KL, Weng MS, Chiang CT, Tsai YJ, LinShiau SY, Lin JK (2005) Comparative studies on the hypolipidemic and growth suppressive effects of oolong, black, pu-erh and green tea leaves in rats. J Agric Food Chem 53:480-489
- ↑ Yang TT, Koo MW (1997) Pharmacol Res 35(6):505-512
Obesity
Recently, resveratrol is found to improve obesity.[1]. Some studies suggest relationship between green tea consumption and reduction in body fat[2][3], but clear evidence on body weight control is missing. Since body weight may change for various reasons, it is hard to conduct an epidemiologic study.
- ↑ Baur JA et al. Sinclair DA (2006) "Resveratrol improves health and survival of mice on a high-calorie diet" Nature 444:337-342
- ↑ Wu CH, Lu FH et al. (2003) "Relationship among habitual tea consumption, percent body fat, and body fat distribution" Obes Res 11:1088-1095
- ↑ Tian WX, Li LC et al. (2004) "Weight reduction by Chinese medicinal herbs may be related to inhibition of fatty acid synthase" Life Sci 74:2389-2399
