Green tea extract may counter fatigue for workaholics
physical and mental fatigue associated with modern stressful lives,
suggests research from Japan.
Oral intake of the tea compound for five days reduced levels of oxidised species related to fatigue in an animal model of fatigue, according to results presented in the journal Nutrition. "Acute fatigue is a normal phenomenon that disappears after a period of rest. In contrast, the effects of accumulated fatigue are sometimes irreversible, and the compensation mechanisms that are useful in reducing acute fatigue are no longer effective," explained lead author Masaaki Tanaka from Osaka City University Graduate School of Medicine. "To avoid fatigue, it is important to develop effective strategies for attenuating fatigue." One such method may be supplements of green tea extract, if the results of the animal study can be repeated in humans. Green tea and its extracts already have a positive reputation, with studies reporting they may offer protective effects against Alzheimer's and certain cancers, improve cardiovascular and oral health, and play a positive role in weight management. Tiring experiments Tanaka and co-workers simulated fatigue in the rats by keeping the animals in a cage filled with 1.5 cm of water for five days. In order to evaluate the extent of their fatigue, they were then subjected to a swimming test with weights attached to their tails. They report that the animals fed with EGCG (type RS-50, Ito En, 50 or 100 mg/kg) could swim longer than fatigued control animals. Levels of thiobarbituric acid reactive substance (TBARS) increased in fatigued control animals, but this increase was attenuated in the fatigue animals fed the green tea extract. "It has been shown that a fatigue load induces oxidative damage (lipid peroxidation) of the liver, and liver damage is associated with fatigue," explained the researchers. "We demonstrated that oral administration of EGCG (50 or 100 mg/kg intraperitoneally [not for 25 mg/kg]) improved performance in an animal model of combined fatigue; this effect may be mediated by its antioxidant properties in the liver," they concluded. Mechanism "Thus, although the relation between the reactive oxygen species relative enzymes and fatigue is currently unclear, a possible mechanism that could account for the antifatigue effect of oral administration of EGCG may be related to protection against oxidative insult in the liver," stated the researchers. Significant further study is required however before the compound can be considered an option for workaholics at risk of accumulated fatigue. Specifically, whether such results are reproducible in humans, what doses are required, and the risk of potential adverse events are of utmost importance. Global tea market The global tea market is worth about €790 (£540, $941) million, with green tea accounting for about 20 per cent of total global production, while black tea accounts for about 78 per cent. Green tea is said to contain over four times the concentration of antioxidant catechins than black tea (green tea leaves that have been oxidized by fermentation), about 70 mg catechins per 100 mL compared to 15 mg per 100 mL for black tea. Consumer awareness of the benefits of green tea and green tea extracts continues to rise with growing numbers of studies, from 430 papers in 2000 to almost 1500 in 2003, reporting benefits of the main compounds, catechins. This has seen European demand surge, having reached 500 metric tonnes in 2003. Companies such as DSM, with its Teavigo boasting 95 per cent purity of epigallocatechin gallate (EGCG), and Taiyo International, with its Sunphenon claiming more than 90 per cent purity, position themselves firmly in specific catechin markets. Source: Nutrition (Elsevier) Volume 24, Pages 599-603 "Effects of (-)-epigallocatechin gallate in liver of an animal model of combined (physical and mental) fatigue" Authors: M. Tanaka, Y. Baba, Y. Kataoka, N. Kinbara, Y.M. Sagesaka, T. Kakuda, Y. Watanabe
