While most people are already aware that oolong tea is good for the health, a month-long experiment by a Japanese doctor showed the tea reduces body fat and rejuvenates internal organs, because it contains a large amount of polyphenol, the Daily Yomiuri Shimbun reports. "I never expected to get the result I wanted from this experiment in such a short period of time," said Masatoshi Nakano, a lecturer at an Aichi Medical University institute. In April, Nakano asked 12 men and women aged between 18 and 39 to participate in an experiment to examine the effect of oolong tea on their health. All the participants had a clean bill of health and a body mass index of between 20 and 30. The participants were effectively asked to soak their lives in oolong tea for a month. They were required to drink at least one litre of oolong tea each day and refrain from drinking water. Participants were also asked to eat a balanced diet during the period. Blood samples were taken from the participants for analysis both before and afterward. Nakano took the blood samples to Yasuharu Mitomo, a professor at Nagoya City University for tests. Dr. Mitomo is specialised in the study of "internal-organ aging." Using various indicators, such as cholesterol and blood sugar levels, and hepatic activity, he has been researching the impact of different lifestyles on the aging process of internal organs. In testing the blood samples, Mitomo used a calculation method he devised for evaluating the age of organs. He used the results of medical checkups as the basis for the calculations. According to his findings, the internal organs of the participants were rejuvenated by an average of 1.9 years and a maximum of nine years. The average age of the 12 participants was 26.9. Before the oolong tea experiment, their average internal organ age was 30.3, and dropped to 28.4 after the experiment. The one whose internal-organ age was rejuvenated by nine years was a woman aged 29. Her cholesterol level fell from 206 before the experiment to 157 afterward, while her LDL (bad) cholesterol level dropped from 137 to 98. Along with the decrease in cholesterol levels, her overall internal-organ age dropped from 38 to her actual age of 29. "The higher the combined level of cholesterol, the harder your arteries become," Mitomo said. Hardening of the arteries is believed to be a common cause of fatal heart attacks and strokes. The combined cholesterol levels of most of the participants fell, as did their g-GTP, an indicator of hepatic activity. Meanwhile, HDL (good) cholesterol rose in many cases. "Although I want to see more results in three months or so, the dramatic improvement in these figures over such a short period of time is extremely interesting," Mitomo said. According to the results, oolong tea helped to reduce body fat during the test period. Nine of the subjects saw a two-centimetre reduction in their waist size, while eight also saw the size of their upper arms reduced by two centimetres. According to Nakano, oolong tea helps the body burn fat more efficiently than other teas, including green tea and black tea. It also helps reduce the build-up of body fat. It has long been believed that oolong tea, which is a good accompaniment for greasy Chinese dishes, helps people lose weight. However, this is the first time a study has found conclusive evidence to support the claim. Nakano intends to present a paper on the findings to the Japan Society for the Study of Obesity in October. According to Nakano, "The effect is a result of the polyphenol contained in oolong tea." "Polyphenols can all stop hardening of the arteries to some extent, but it is the size of the polyphenol molecules in oolong tea that is so remarkable," he said. He said the molecules form a perfect match with hormone-sensitive lipase, an enzyme that dissolves body fat. This match activates the enzyme. The size of polyphenol molecules varies from tea to tea depending on the level of fermentation. In the case of green tea, which is not fermented, the size of the molecules is half that of oolong tea. In the case of black tea, which is fully fermented, the molecules are about twice the size of those in oolong tea. Therefore, neither green tea nor black tea can dissolve body fat to the same degree as oolong tea, which is only half fermented. Ultimately, though, gulping down gallons of oolong tea alone will not keep you trim. "While it is true that oolong tea dissolves fat efficiently, you also need to consider keeping a balanced diet," he said. "Polyphenol is contained in more or less every plant, so to avoid hardening of the arteries you do not necessarily have to drink oolong tea, you could just eat a lot of vegetables," he added.