Sixty men and women, aged 32 to 73, who had slightly elevated blood sugar throughout the day (prediabetic), took green tea extract powder containing 456 mg of antioxidants called catechins per day. Half took green tea for two months and then stopped for two months, while the other half did the opposite.
In the first group, blood sugar levels returned to normal after two months of taking green tea and stayed normal for the next two months after they had stopped taking it. Blood sugar levels also returned to normal after taking green tea for two months in the second group. Researchers think that green tea reduces the amount of sugar (glucose) the small intestine absorbs from food.