Green tea improves seniors' cognitive function
SENDAI, JAPAN - According to a new study by Japanese researchers, green tea improves the cognitive function and general health of seniors. The study, which was published online on January 25 in the American Journal of Clinical Nutrition, was conducted by researchers Tohoku University Graduate School of Medicine.
The researchers evaluated whether green tea drinkers have a lower risk of frailty and disability as they grow older. They found that a higher consumption of green tea was associated with a lower prevalence of cognitive impairment in humans.
Yasutake Tomata of the Tohoku University Graduate School of Medicine and his colleagues followed 13,988 adults aged 65 or older for three years. We conducted a prospective cohort study in 13,988 Japanese individuals aged ≥65 y. Information on daily green tea consumption and other lifestyle factors was collected via questionnaire in 2006. Data on functional disability were retrieved from the public Long-term Care Insurance database. They reported that the seniors who regularly drink green tea tended to remain more agile and independent than their peers over time. They found those who drank the most green tea were the least likely to develop "functional disability," or problems with daily activities or basic needs, such as dressing or bathing. Specifically, almost 13% of seniors who drank less than a cup of green tea per day became functionally disabled, compared with just over 7% of individuals who drank at least five cups a day.
Green tea contains antioxidant s, which have been reported to reduce cellular damage that can result in disease. The authors wrote: "Green tea consumption is significantly associated with a lower risk of incident functional disability, even after adjustment for possible confounding factors.”
The study did not prove that green tea alone was responsible for improved physical and mental health as one aged. For many green tea drinkers, consumption of the beverage is a component of a healthy life style. These individuals generally had healthier diets, including more fish, vegetables and fruit, as well as more education, lower smoking rates, fewer heart attacks and strokes, and greater mental acuity. Furthermore, they tended to be more socially active and have more support from friends and family. However, even when these factors were taken into account, green tea itself was associated with a lower disability risk, the authors noted.
Individuals who consumed at least five cups a day were one-third less likely to develop disabilities than those who had less than a cup per day. In addition, those individuals who averaged three or four cups a day had a 25% lower risk. Although the researcher were unable to offer an explanation for the health benefits of green tea, the researchers noted that a recent study reported that green tea extracts seem to boost leg muscle strength in older women.
Green tea and its extract are classified as a GRAS (generally regarding as safe) substance bty the US Food and Drug Administration; however, they do contain caffeine and small amounts of vitamin K, which can increase the ability of blood to work. This could reduce the effectiveness of blood-thinning drugs such as warfarin (Coumadin).
Reference: American Journal of Clinical Nutrition