The study – published in the American Journal of Clinical Nutrition – shows that drinking epigallocatechin gallate (EGCG) green tea on a regular basis could result in elderly people being more agile and independent than their peers. The Japanese researchers followed nearly 14000 elderly people for three years – monitoring green tea consumption and data on ‘functional disability’.
The authors explained that the term ‘functional disability’ refers to problems with daily activities, such as going to the shop, doing housework, or difficulty with more-basic needs like dressing and bathing.
“In this study, we found significant inverse dose-response associations between green tea consumption and incident functional disability,” said the researchers, led by Yasutake Tomata, of Tohoku University Graduate School of Medicine, Japan.
“To our knowledge, this is the first reported study to have proved the relation between green tea consumption and incident risk of functional disability,” they said.
Tea is the most frequently consumed beverage in the world, with three billion kilograms of tea produced worldwide annually.
The health effects of green tea have been extensively investigated by many studies – with research linking consumption is significantly associated with a lower risk of pneumonia, mortality from stroke, in addition to a lower incidence of cognitive impairment, and the risk of certain cancers.
“Because of the high rates of tea consumption in the global population, even small effects on an individual could have a large impact on public health,” said Tomata and his colleagues.
In the new study, the Japanese researchers looked at a whether green tea drinkers have lower risk of frailty and disability as they grow old by gathering information on daily green tea consumption and other lifestyle factors via questionnaire in 2006, with data on functional disability retrieved from the public Long-term Care Insurance database over the following three years.
The study followed 13,988 Japanese adults aged 65+ for three years, categorising consumption ‘never’, ‘occasionally’, or ‘1–2’, ‘3–4,’ or ‘more than 5’ cups per day.
Tomata and his colleagues found that people who drank the most green tea were the least likely to develop "functional disability" over the next three years.
They reported that 7.1% of Japanese adults who drank at least five cups of green tea a day became functionally disabled, compared with 8% who drank 3–4 cups, 11% who drank 1–2 cups, and 13.3% who consumed less than one cup per day.
The authors said that future research should involve randomised controlled trials on green tea consumption, which could help to confirm any protective effect of green tea against functional disability.
Source: American Journal of Clinical Nutrition
Published online ahead of print, doi: 10.3945/ajcn.111.023200
“Green tea consumption and the risk of incident functional disability in elderly Japanese: the Ohsaki Cohort 2006 Study”
Authors: Y. Tomata, M. Kakizaki, N. Nakaya, T. Tsuboya, T. Sone, S. Kuriyama, A. Hozawa, I. Tsuji