Visceral fat levels decreased by 9.5 cm2 after twelve weeks of consuming the catechin-enriched beverage, compared with a control beverage with normal levels of green tea catechins, according to results of a study with 118 obese Chinese.
The benefits of the beverage may be linked to a combination of the catechins and caffeine, report researchers from Peking University, the Chinese Center for Disease Control and Prevention, and Japan’s Kao Corporation in the Journal of Functional Foods.
The study adds to a compelling body of science supporting the potential weight management potential of green tea.
The majority of science on tea has looked at green tea, with benefits reported for reducing the risk of Alzheimer's and certain cancers, improving cardiovascular and oral health.
Green tea contains between 30 and 40 per cent of water-extractable polyphenols, while black tea (green tea that has been oxidized by fermentation) contains between 3 and 10 per cent. Oolong tea is semi-fermented tea and is somewhere between green and black tea. The four primary polyphenols found in fresh tealeaves are epigallocatechin gallate (EGCG), epigallocatechin (EGC), epicatechin gallate (ECG), and epicatechin (EC).
The catechin-enriched beverage used in this study contained 125.5 mg of EGCG per 350 ml serving of tea, compared with about 15 mg in a standard commercial tea beverage. The enriched tea also contained 107 mg of EGC, compared with 12 mg in a standard beverage, 40 mg of ECG, compared with a standard 5 mg, and 34 mg of EC, compared with 3.5 mg in a standard beverage.
The total concentration of catechin in the enriched tea was 609 mg per serving, compared with only 86 in the standard (control) beverage.
The enriched tea also contained more caffeine that a standard tea product – 69 mg per serving vs 40 mg per serving. Both control and test beverages were provided by the Kao Corporation.
Obese Chinese were randomly assigned to receive either one serving of the enriched beverage or the control daily for 12 weeks.
At the end of the intervention period the researchers noted that “average visceral fat area, body weight, and body fat were reduced significantly by catechin-enriched green tea treatment but these effects were not seen in the control group”.
With the World Health Organization estimating that by 2015, there will be more than 1.5 billion overweight consumers, the opportunities for a scientifically-substantiated weight management product are impressive.
The slimming ingredients market can be divided into five groups based on the mechanisms of action – boosting fat burning/ thermogenesis, inhibiting protein breakdown, suppressing appetite/boosting satiety (feeling of fullness), blocking fat absorption, and regulating mood (linked to food consumption).
The market for food, beverage and supplement weight management products is already valued at $3.64bn (2009 figures) in the US, according to Euromonitor. In Western Europe, the market was worth $1.3bn in 2009.
Source: Journal of Functional Foods
Published online ahead of print, doi: 10.1016/j.jff.2011.12.010
“Effects of catechin-enriched green tea beverage on visceral fat loss in adults with a high proportion of visceral fat: A double-blind, placebo-controlled, randomized trial”
Authors: Y. Zhang, Y. Yu, X. Li, S. Meguro, et al.