The use of green tea in treating obesity

Abstract

Obesity has been increasing at an alarming rate in the last several decades, both in developed and in developing countries, reaching epidemic proportions among young people and adults as well. Unfortunately, nowadays obesity has become a global health problem. It raises the risk of morbidity from a great number of diseases like: diabetes mellitus Type 2, dyslipidemia, arterial hypertension, coronary heart disease, stroke, cancer and respiratory problems including sleep apnea, etc. Both the direct and indirect costs of obesity and obesity-related morbidity have strong economic impact on the whole society. Therefore, the prevention and treatment of obesity remain and should be a priority worldwide. Besides other possible ways of treatment, phytotherapy has an important role in both scientific research and traditional medicine as well. Green tea beverage made from the dried, non-fermented leaves of the plant Camellia sinensis, has been consumed by humans for thousands of years. It has attained high reputation as a health promoting herb. The increasing interest in the effects of green tea is directed towards its ingredients: catechins, caffeine and theanine, all of which possess various biologically and pharmacologically effects. Some of these compounds are highly attractive in drug discovery programs. It is traditionally thought that green tea consumption decreases the risks for obesity, reduces body weight and helps in treating overweight patients. Consequently, health abnormalities related to obesity may be alleviated by green tea consumption. A number of extensive experimental research and epidemiological studies supported the anti-obesity effects of green tea and its various forms, and proposed very complicated mechanisms concerning its potential influence on the body weight and composition. At least, the modulation of lipid and carbohydrate metabolism, body energy balance and food intake could be obtain by consuming green tea. Its antioxidant effects in treating obesity are also exploited. Green tea and its commercial forms (which generally contain ingredients like catechins and caffeine in a higher concentration than the typical green tea beverage) have proved to be highly successful in controlled experiments, but they did not demonstrate identical and unambiguous effects in randomised clinical trials (RCTs). That is the reason why its safety and efficacy could not be properly judged and claimed to be a complementary and alternative medicine used to aid weight loss and weight maintenance. To overcome the problem of the insufficient number of RCTs, a lot of systematic reviews and meta-analyses have been conducted. However, in spite of some benefits shown in decreasing body weight and weight maintenance, the obtained improvement, in general, did not reach statistical significance. That could be the result of great heterogeneity of these trials. Thus, well-characterised, randomised controlled clinical trials are needed in order to assess the promising effects of different forms of green tea on health promotion in overweight and obese humans. In order to avoid possible misleading and aggressive commercial practices conducted by the advertisers, such reliable information is extraordinary important for health-care workers, and for green tea consumers as well.