Green tea, green tea extract and its derivatives have become a popular health food. Epidemiological studies (1, 2, 3) show an association of populations that drink green tea and improved health. They have less hypertension and heart disease, and fewer strokes. And they live longer. Because of these studies, laboratory research has been done on green tea, green tea extract, and various polyphenols found in green tea.
Green tea has a high potassium to sodium ratio. As we've discussed in previous posts the foods with the most beneficial effects on hypertension, strokes and heart disease have a high potassium to sodium ratio. Many of the accompanying substances in these foods boost the benefits provided by the favorable potassium sodium ratio. This is one of the reasons it is important to get your potassium in foods instead of pills. The pills don't include the accompanying substances.
Green Tea And EGCG
One substance in green tea that has been extensively studied is EGCG, an active polyphenol. A recent study showed that EGCG, has among its other beneficial effects, an effect on the mitochondrial potassium channels. The mitochondria are the power plants of the cell. They provide energy for all the work the cell does. When the power plants shut down, the cell dies.
How EGCG Helps
A recent study (4) looked the effect of EGCG on a simulated heart attack. It showed that EGCG helps protect the heart muscle cell from dying during a heart attack. The study found that EGCG acted on a potassium channel in the mitochondria of the heart muscle cells. It opened the channel to let more potassium into the mitochondria.
This blocked calcium from getting into the mitochondria. When calcium builds up in the mitochondria, the mitochondria shut down. When they shut down, the cell dies. In the heart this results in an area of dead muscle cells medically known as an infarct. In this study, EGCG reduced the size of the infarct.
Of course, a high ratio of potassium to sodium in your diet helps prevent the heart attack in the first place. And like many of the other high potassium foods, green tea brings additional warriors to the battle against heart disease. Like resveratrol and the polyphenols in wine, EGCG in green tea is one of the warriors.
Tables Of High Potassium Foods
To find tables of high potassium foods, and the potassium and sodium content of the food, go to the List of Posts page on the tab at the top of the page. It lists the posts by type of post. Look for a food group your food of interest would be in. Then look for the word “table” in the link.
1. The impact of green tea and coffee consumption on the reduced risk of stroke incidence in Japanese population: the Japan public health center-based study cohort. Kokubo Y, Iso H, Saito I, Yamagishi K, Yatsuya H, Ishihara J, Inoue M, Tsugane S. Stroke. 2013 May;44(5):1369-74. doi: 10.1161/STROKEAHA.111.677500. Epub 2013 Mar 14.
2. The protective effect of habitual tea consumption on hypertension. Yang YC, Lu FH, Wu JS, Wu CH, Chang CJ. Arch Intern Med. 2004 Jul 26;164(14):1534-40.
3. Green tea consumption and mortality due to cardiovascular disease, cancer, and all causes in Japan: the Ohsaki study. Kuriyama S, Shimazu T, Ohmori K, Kikuchi N, Nakaya N, Nishino Y, Tsubono Y, Tsuji I. JAMA. 2006 Sep 13;296(10):1255-65.
4. Polyphenol (-)-epigallocatechin gallate during ischemia limits infarct size via mitochondrial K(ATP) channel activation in isolated rat hearts. Song DK, Jang Y, Kim JH, Chun KJ, Lee D, Xu Z. J Korean Med Sci. 2010 Mar;25(3):380-6. doi: 10.3346/jkms.2010.25.3.380. Epub 2010 Feb 17.