Green Tea Outperforms Black for Heart Protection

A seemingly slight difference in fermentation processes creates an enormous potential health benefit of green tea over black.

Black and green tea start the same way, as leaves on Camellia sinensis, an evergreen shrub that can grow to the height of a tree but is cultivated as a bush on tea plantations. A few times a year, the buds and the tender, young leaves at the top of the bush are picked and then dried on racks. But those dried tea leaves aren’t ready for the teapot.

The next step is fermentation, as enzymes begin to break down other natural chemicals in the leaf. In black tea, the fermentation is allowed to do its thing, producing a darkly colored, robustly flavored tea. But in green tea, fermentation is brought to a halt by heating: after drying, the leaves are lightly steamed or gently pan-fried in huge woks.

This seemingly slight difference in processing creates an enormous difference in the chemical composition — and the potential impact on your health — of green tea as compared to black. That’s because the natural chemicals persevered in green teas are a group of catechins — an antioxidant more powerful than vitamins A, C, and E in stopping the “free radical” damage to cells that can trigger chronic disease and speed aging. Green tea consists of 30-42% catechins, while black tea has 3-10%.

The latest evidence of the power of catechins: a new study showing that green tea — but not black — protects against coronary artery disease (CAD).

For the study, Chinese researchers analyzed the results of 18 other studies on green and black tea and CAD. They found that people who drank the most black tea had an 8% lower risk of CAD compared to people who drank the least. In other words, hardly any difference at all. But people who drank the most green tea had a 28% lower risk of CAD compared to people who drank the least. They also found that each additional cup of green tea per day lowered risk by 10% (10% for one cup, 20% for two cups, 30% for three cups, etc.).

“Because of the different degrees of fermentation, the content and composition of catechins vary substantially between green and black tea,” wrote the researchers in the American Journal of Clinical Nutrition. “Green tea catechins have been shown to inhibit oxidation, vascular inflammation, atherogenesis, and thrombogenesis and to favorably modulate the plasma lipid profile and vascular reactivity, which suggests a wide spectrum of beneficial effects on CAD.”

And there are more benefits to green tea than reducing the risk of CAD. Green tea is also rich in L-theanine, a unique amino acid that increases mental clarity while calming you down.

So enjoy a cup of green tea today — or two…or three!

References

"Black and green tea consumption and the risk of coronary artery disease: a meta-analysis." Am J Clin Nutr. 2011 Mar;93(3):506-15. Epub 2011 Jan 19. Wang ZM, Zhou B, Wang YS, Gong QY, Wang QM, Yan JJ, Gao W, Wang LS.