Tea extract subjects burned 4 percent more calories, and overall energy expenditure rose 4.5 percent. Although previous studies had determined that caffeine could increase metabolic rates at higher doses, the results of this trial could not be attributed to caffeine, since the subjects receiving only caffeine, in an amount equal to that found in green tea, experienced no change in energy expenditure or calorie burning. In another recently reported Japanese study, research supported by the National Cancer Institute found green tea inhibited cancer cell growth. Breast cancer patients consuming more than five cups daily remained disease free longer and experienced a lower recurrence rate than patients consuming fewer than four cups daily. Oxidative stress has been implicated both in the aging process and in the pathological changes associated with Alzheimer's disease.
Antioxidants help provide protection against free radical damage.
In this study, investigators examined the association between blood levels of antioxidants, including vitamins A, C and E, and selenium, and memory in a multiethnic population of senior citizens. The researchers examined 4,809 people aged 60 or older between 1988 and 1994. These people were at least twice as likely to report problems managing their money or preparing meals. Increasing levels of vitamin E were associated with better memory performance for this ethnically diverse elderly population. The researchers report that they found no connection between the other antioxidants and memory loss.