Green tea is purported to offer a plethora of health benefits, from cancer prevention to mental clarity and reduced risk of Alzheimer’s disease. And as proponents of natural weight control aids have long suspected, it appears we may be able to confidently add fighting fat to the offerings from the green tea “medicine chest.” Further, it appears to reduce abdominal fat, the type most detrimental to health, and to lower high triglycerides, which may reduce heart disease risk.
A fat-fighting brew
Catechins are naturally occurring compounds found in green tea, dark chocolate, beans, berries, apples, red wine, and black tea. Green tea is the richest source of these nutrients.
For this study, researchers randomly assigned 107 sedentary (non-exercising), overweight men and women to consume either:
• 2 cups (500 ml) per day of a green tea beverage that provided 625 mg of catechins
• 2 cups (500 ml) per day of a similar, catechin-free beverage
Both study beverages provided 39 mg of caffeine and 15 calories. Study participants were instructed to get at least 180 minutes per week of moderate intensity physical activity and everyone received three supervised exercise sessions per week to help them reach this goal.
After 12 weeks, the researchers found that the two groups lost similar amounts of weight and had similar percent changes in total fat mass, but the catechin-beverage group fared far better in terms of abdominal fat loss and decreased triglyceride levels.
The catechin group decreased total abdominal fat area by 7.7% and decreased subcutaneous abdominal fat, the type just underneath the skin, by 6.2%. By comparison, the catechin-free group had decreases of only 4.4% and 3.3% in total abdominal fat area and in subcutaneous fat, respectively. Since abdominal fat is more damaging to health than fat accumulated in other body areas, these results are encouraging.
Most impressively, the catechin beverage group decreased triglyceride levels by an average of 11.2% from baseline compared with a decrease of only 1.9% in the catechin-free group.
Should you give green tea a go?
One cup of regular green tea contains up to 150 mg of catechins, so to reach the levels of the catechin-enriched study beverage, you’ll need to drink 4 to 5 cups per day. (Keep in mind that many coffee mugs contain close to 2 cups, which translates to about 2 1/2 mugs per day.) To best enjoy green tea, and to maximize its health benefits, keep the following in mind:
• The caffeine in 5 cups of green tea is similar to amounts found in about 2 cups of coffee. To avoid the jitters, coffee drinkers should replace some coffee with green tea instead of simply adding green tea to their coffee quota.
• To maximize the catechin content of your brew, let the tea steep for at least two or three minutes.
• To avoid a bitter brew, make green tea with water that is not quite boiling.
• In general, loose leaf green tea will yield more catechins than similar sized leaves in tea bags. However, if you dunk the tea bag up and down and squeeze it when removing from the cup, you’ll get nearly as many healthful catechins as you would from loose leaves.
• The more finely ground the tea leaves, whether in a bag or loose leaf, the more catechins you’ll have in the resulting brew.
• Simply drinking more calorie-free fluids may help with your weight loss goals, so if you find 5 cups of green tea to be too much, replace a couple with plain water.
Finally, remember that the study participants seriously ramped up exercise levels. Green tea is no miracle cure. All the green tea in the world is unlikely to do the trick on its own, so be sure to add some movement and healthful foods.
(J Nutr 2009;139:264-70)
Suzanne Dixon, MPH, MS, RD
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