Effect of Tea for Healthy

Effect of tea that are beneficial to health has been demonstrated in experimental studies using animal and human studies. Two of the most intensively investigated diseases are heart disease and cancer.
Although the mechanism of protective activity of tea against the disease have been proposed, there are inconsistencies in the relationship between tea consumption and risk of the disease in humans.
LOT epidemiological studies have investigated the effect of tea consumption on cardiovascular disease. On a long-term study in the Netherlands, tea consumption is associated with lower risk of death from coronary heart disease and stroke incidence rates.
In a study in Rotterdam, the best relationship of tea intake with severity of aortic atherosclerosis was observed. Health study in Boston found that subjects who drank one cup (200-250 ml) or more of black tea per day had approximately half the risk of a heart attack compared with people who do not drink tea.
One mechanism proposed for the possible protective effects of tea consumption on cardiovascular disease is that tea polyphenols inhibit LDL oksidari, which is known to be involved in the development of atherosclerosis.
Studies have indicated that black tea consumption has been protecting LDL against oxidation ex vivo. Tea polyphenols on LDL particles accumulate after 3 days of consumption of green tea or black, but their level is not sufficient to strengthen the resistance to LDL oxidation.
Hypocholesterolemic activity of tea may also contribute to protection against heart disease. In animals fed high fat and cholesterol, green tea, black tea and tea polyphenols has prevented an increase in serum and liver liida, had lower serum total cholesterol or atherogenic index, and has increased the fecal excretion of total lipids and cholesterol.
When hamsters were fed a high fat, hamsters fed green tea or green tea plifenol have total serum cholesterol and triacylglycerol levels of fecal fat excretion is low but higher than the control group.
However, epidemiological studies and trials in humans have failed to demonstrate a serum cholesterol lowering effect of green or black tea consumption. From 13 epidemiological studies, only four reported an inverse relationship. Another potential mechanism may be through the effect of tea on weight and body fat.
Recent observations that intragastric administration of black tea has inhibited platelet aggregation and has prevented experimental coronary thrombosis in dogs and the consumption of green tea polyphenols had lower ADP-induced platelet aggregation that provides a possible mechanism for the prevention of cardiovascular disease. However, green tea extract which is equivalent to 10 cups (2 liters) tea for 4 weeks had no significant effect on some indicators related to cardiovascular disease.
Black and green tea has led to a large increase in acute (30 minutes after ingestion) on blood pressure than caffeine alone. However, regular tea consumption did not alter blood pressure.
Tea and cancer
Tea has been considered as a cancer preventive beverage for such activities has been demonstrated in many animal models.
These models include skin cancer, lung, esophagus, stomach, liver, small intestine, pancreas, colon, bladder, prostate, and mammary glands. The tea is usually given to animals as the sole source of liquid beverages.
Extensive studies on UV light-induced tumorigenesis and as a chemical-induced lung tumors and chemicals that occur spontaneously in mice have indicated that tea has broad inhibitory activity against tumorigenesis and effective when administered during the insiasi, promotion or progression of carcinogenesis. This conclusion may also be applied to other models.
Have reported conflicting results regarding the effect of tea on colon carcinogenesis: inhibition and lack of barriers both have been reported. Inhibition of mammary gland tumorigenesis induced chemically by the tea has been observed in rats fed high fat. EGCG has been shown to inhibit cell growth of human breast and prostate cancer.
Many mechanisms have been proposed regarding the inhibitory action of tea against carcinogenesis. The most common mechanism of antioxidative activity, but many other mechanisms are also important. Antiproliferative effects of tea catechins have been demonstrated in models of lung and skin tumorigenesis in mice. Barriers to cell transformation and cell growth by catechin and theaflavin pure has also been reported.
Activity has been linked to resistance activator activity protein 1 (AP-1). Because the activation of AP-1 that is often in many human cancers, this action may be applicable to human cancer prevention. Inhibition of enzymes associated with tumor promotion, such as ornithine decarboxylase, protein kinase C, and sikloosigenase lipoksigenase by tea has been shown. The relationship between body fat decreased by tea and skin tumorigenesis barrier has been observed.
Mice who drank black tea or green tea have fewer lung tumors and weighed less than controls, even though they consume the same amount or more food. Based on the inhibitory activity of a variety that has been observed in different animal models and cell cultures of different cancers, it may be that the content and the mechanisms involved in the tea that multiple barriers carcinogenesis.
Effects of tea on nutrition
Obesity in mice, the consumption of oolong tea for 10 weeks has prevented obesity and fatty liver. Decreased nutrient absorption and increased energy burning may both contribute to these effects.
Green tea extract stimulated thermogenesis of adipose tissue in mice to a greater extent than can be done by caffeine alone. Green tea extract ingestion by healthy young men with every meal produced a significant increase in energy burning 24 hours.
These studies have indicated that tea polyphenols inhibit the activity of catechol-O methyltransferase and acts synergistically with caffeine to prolong sympathetic stimulation of thermogenesis.
Does the consumption of tea interfere with absorption of protein in humans still needs to be investigated further. Due to the strong binding affinity of tea polyphenols against metal ions, the effect of tea on the absorption of nutrients is probably an important thing.
Decrease iron absorption because of drinking tea has been reported. Apparently the effect was mainly on nonheme iron, and when tea and iron are consumed together. Heme iron absorption from cooked meat is not affected by tea consumption.
Among women aged 65-76 years, tea consumption is associated with bone mineral density measurements of a larger, consistent with reports that tea is protective against hip fractures. The data indicate that components other than polyphenols, such as phytoestrogens or fluoride, may affect bone mineral density. Tea was found to inhibit the activity of glucosyltransferase from streptokokki oral and dental caries development in rats. Tea contains fluoride which may strengthen tooth enamel and improve dental health.
In the murine model of collagen-induced arthritik, green tea polyphenols significantly reduce the incidence and severity of arthritis. Expression of inflammatory mediators, including cyclooxygenase-2, interferon gamma, and TNF-alpha was lower in the joints arthritik of mice fed green tea polyphenols. Cataracts, which develops as a result of precipitation of proteins in the lens of the eye, may be reduced by increased consumption of tea. 


Source : kompas cyber media