Good news about the health benefits of green tea
The National Center for Complementary and Integrative Health is funding a variety of research on green tea. Scientists are studying the effects of high doses of tea components on the liver, whether green tea can be helpful for iron overload disease, and the safety and potential benefits of a component of green tea in people who are HIV-positive.
Green tea research has shown promise in reducing the symptoms of rheumatoid arthritis (RA), and the National Center for Complementary and Integrative Health recommends green tea be further explored as a dietary therapy to be used alongside conventional treatments for RA.
So far, the National Institutes of Health says there’s evidence of these health benefits of green tea:
- Green tea enhances mental alertness, likely because of its caffeine content.
- An ointment made from a specific green tea extract, Veregreen, has been shown to be an effective treatment for genital warts and is approved by the Food and Drug Administration.
- Although there have been few long-term studies investigating whether tea reduces the risk of heart disease, evidence suggests both green and black tea have beneficial effects on blood pressure and cholesterol.
Green tea and cancer prevention
Most studies of tea and cancer prevention have focused on green tea. In animal studies, green tea and the polyphenols it contains have been found to inhibit the growth of skin, lung, oral cavity, esophagus, stomach, small intestine, colon, liver, pancreas, and breast cancers, the National Cancer Institute points out.
Over the past decade, more than 50 epidemiologic studies (which analyze potential causes of diseases or health conditions in populations) have looked at the association between tea consumption and cancer. The results of these studies have often been inconsistent, and the National Cancer Institute says that could be explained because of differences in the types of tea consumed and how it was prepared. However, some of these large population studies have linked tea consumption to reduced risks of colon, breast, ovary, prostate, and lung cancer.
Although more clinical research is needed to see how green tea may impact cancer risk, a few clinical studies so far have had positive outcomes. For example, two trials looked to see if green tea had any impact on urine levels of 8-hydroxydeoxyguanosine (8-OHdG), a biomarker of oxidative DNA damage linked to an increased risk of cancer.
In one study of heavy smokers, those who drank green tea had a significant 31 percent decrease in urinary levels of 8-OHdG after drinking four cups of green tea a day. In other research, 124 people at increased risk of liver cancer due to hepatitis B virus infection and exposure to aflatoxin (a cancer-causing toxin produced by certain molds) were given either a placebo pill or a supplement containing green tea polyphenols. Compared with those in the placebo group, the research subjects who took the green tea supplement had dramatically lower urinary 8-OHdG levels.
Bottom line: While research does indicate green tea holds promise as a cancer fighter, much more research is needed. For now, the evidence regarding the potential benefits of tea consumption in relation to cancer is inconclusive, according to the National Cancer Institute.
April 09, 2020
Janet O’Dell, RN