Back in March one of my blog posts focused on the effects of green tea constituents known as catechins had on the metabolism of fat in the body. A recent study has found that green tea catechins stimulated fat-burning in the body, something which is an obvious boon to individuals seeking to attain or maintain a healthy weight. This study came on the back of other evidence which suggests that catechins can indeed promote fat loss in the human body [1].
Further evidence for the weight loss promoting effects of catechins has come in the form of another study published recently in the Journal of Nutrition [2]. In this study, 107 individuals were given a daily beverage containing 625 mg of catechins or a drink containing no catechins for a period of 12 weeks. 625 mg of catechins is amount to be found in the equivalent of about 5 cups of green tea. Both drinks also contained identical amounts (39 mg) of caffeine.
Over the 12-week study period, individuals were advised to partake in three hours or more of moderate intensity activity each week. 3 or more exercise sessions were supervised.
At the beginning and end of the study, participants underwent a variety of measurements including body composition and the ‘abdominal fat area’ (a measure of amount of fat in and around the abdomen). Higher abdominal fat area readings are a concern because it is fat in this region of the body that is most strongly correlated with an increase in risk of chronic diseases such as type 2 diabetes and heart disease.
The results of this study found that changes in overall fat levels (fat mass) in the body were not different between the two groups. However, fat area in the abdomen was significantly lower in the group consuming the catechin-laced beverage. As an added bonus, levels of blood fats known as triglycerides were significantly lower the catechin-consuming group too. This is good news because raised triglyeride levels are associated with an increased risk of heart disease.
Taken as a whole, this and previous research suggests that catechins derived from green tea may boost the body’s metabolism of fat, particularly abdominal fat. It might also be borne in mind that other research has linked green tea with potential protection from conditions such as cardiovascular disease and breast cancer.
A word of caution though: a recently published study found evidence that green tea components appear to block the action of the chemotherapy drug bortezomib (Velcade) [4]. Those taking this drug should consult their doctors regarding green tea use.
References:
1. Nagao T, et al. Ingestion of a tea rich in catechins leads to a reduction in body fat and malondialdehyde-modified LDL in men. American Journal of Clinical Nutrition 2005;81(1):122-129
2. Maki KC, et al. Green Tea Catechin Consumption Enhances Exercise-Induced Abdominal Fat Loss in Overweight and Obese Adults. J Nutr 2009 139: 264-270.
3. Khokhar S, et al. Total phenol, catechin, and caffeine contents of teas commonly consumed in the United Kingdom. J Agric Food Chem. 2002;50(3):565-70.
4. Golden EB, et al. Green tea polyphenols block the anticancer effects of bortezomib and other boronic acid-based proteasome inhibitors. Blood. 2009 Feb 3. [Epub ahead of print]
