Regular green tea drinkers have a lower risk of developing functional disability, researchers from Tohoku University Graduate School of Medicine, Sendai, Japan, reported in the American Journal of Clinical Nutrition. Functional disability refers to problems with daily chores and activities, such as bathing or dressing.
As background information, the authors explained that prior studies had found that consuming green tea reduced the risk of diseases associated with functional disability, such as osteoporosis, cognitive impairment and stroke. Although most experts believed the risk of incident functional disability would be lower for regular green tea drinkers, no direct studies to prove this had ever been carried out.
Yasutake Tomata and team set out to determine whether regular green tea consumption might reduce incident functionality disability in older people.
In 2006, they gave out questionnaires regarding daily tea consumption, as well as other lifestyle factors and gathered data on 13,988 respondents. All the respondents were at least sixty-five years of age. They used the public Long-term Care Insurance database for information on functional disability.
They found a close inverse link between functional disability risk and the consumption of green tea - the more people drank green tea, the lower their risk.
Nearly 13% of those who consumed less than one cup of green tea each day developed functional disability, compared to slightly more than 7% among those consuming five cups or more.
The authors stressed that their study in no way proves that it is just the green tea that protects against functional disability as people age. They also noticed that the heavy green tea drinkers also ate more fruit and vegetables, consumed more fish, were less likely to smoke, had fewer strokes and/or heart attacks, and tended to have a higher level of education. They were also found to have sharper cognitive function.
The greater tea drinkers tended to have a wider circle of friends and more family members around them.
However, even when all those above-listed factors were taken into account, there was still a link between regular green tea drinking and less functional disability risk.
Nobody is yet certain why green tea offers these benefits. The authors mentioned one prior study which demonstrated that green tea extracts help maintain leg muscle strength in elderly females.
They warn that there is a chance green tea extracts, such as caffeine and vitamin K, might interfere with how anticoagulant drugs work.
In an abstract in the journal, the authors wrote:
"Green tea consumption is significantly associated with a lower risk of incident functional disability, even after adjustment for possible confounding factors. "
Japanese green tea
Green tea (Ryokucha) is common throughout Japan, and is simply known there as tea (ocha).
Historians say green tea was originally used in China during the Song Dynasty (A.D. 960-1279). A Japanese Buddhist priest, Myōan Eisai (A.D. 1141-1215), who also set up the Rinzai school of Zen Buddhism, brought green tea to Japan.
In Japan, green tea is graded, according to its quality, what part of the plant it comes from, and how it is processed. The country's best green tea comes from the Yame region of Fukuoka Prefecture, as well as the Uji region of Kyoto.
There are several names for different types of Japanese green tea, including Gyokuro, Kabusecha, Sencha, Fukamushicha, Tamaryokucha, Bancha, and Kamairicha.
Ingredients in green teaGreen tea is known to contain the following:
- Polyphenols - especially catechins (epigallocatechin gallate)
- Vitamin C (ascorbic acid) and vitamin K
- Several minerals - including zinc chromium, selenium, and manganese
- Certain phytochemical compounds
Researchers at Cambridge University Hospitals found that pomegranate, turmeric, broccoli and green tea help prevent and halt prostate cancer, the most common cancer in men in the USA and UK.
Written by Christian Nordqvist