A study was recently published in the Journal of the American College of Cardiology. The report mainly compared the effects of coffee and green tea in people with high blood pressure. For people with high blood pressure, coffee or green tea? Today we will come to this topic. Hello everyone, I am nutritionist Wang Yan, health is our greatest wealth, let's manage it together. 
First, let's understand what high blood pressure is and what severe high blood pressure is. High blood pressure is the pressure on the walls of blood vessels as blood circulates through them. The pressure generated when the heart contracts is called systolic blood pressure, which is often referred to as high pressure; When the heart expands, the pressure of blood on the walls of blood vessels is called diastolic pressure, and as you can imagine, the pressure during contraction is high, so it is called high pressure. Under normal circumstances, our systolic blood pressure (high pressure) should not exceed 130 mm Hg and diastolic blood pressure (low pressure) should not exceed 80 mm Hg. If your blood pressure is above 90 mm Hg, it's severe hypertension. 
The reason why we want to distinguish between general hypertension and severe hypertension is related to the research that will be presented next. Because the study was done in more detail, it classified hypertension into five levels: 130-140 mmHg, 85-90 mmHg, which is high to normal; When is high blood pressure? 140-90 mmHg, known as Grade 1; 160-100 mmHg, known as secondary; 180-110 mmHg, that's it**. In other words, a high pressure of 160 mm Hg and a low pressure of more than 100 mm Hg are considered severe hypertension.
The results of the study found that people with high pressures of 160 mm Hg and low pressures of 100 mm Hg or more had twice the risk of dying from heart disease if they drank coffee. This tells us a clear conclusion: if you have severe high blood pressure, don't drink or drink less coffee. Some people will ask, is there a problem with people with blood pressure below 160 mm Hg? Judging by the research report, the impact is not significant.
Theoretically, coffee stimulates our sympathetic nerves, causing a higher heart rate and higher blood pressure, which is really a matter of degree. In conclusion, if you have severe high blood pressure, high blood pressure above 160 mm Hg and low pressure above 100 mm Hg, probably don't drink coffee or no more than one cup.
So, does green tea have any effect? The results of the study found that these people with high blood pressure, even if the high blood pressure was above 160 mm Hg and the low blood pressure was above 100 mm Hg, drinking the same amount of green tea did not affect the mortality rate due to heart disease. In other words, it's safer to drink green tea. Why is this so?
Both coffee and green tea contain caffeine, why does coffee increase the risk of heart disease while green tea does not? This may be related to many other factors contained in green tea, such as the polyphenols it contains, which have anti-inflammatory and antioxidant effects, one of which is called catechins, which make up more than 75% of the polyphenols in tea.
Why is tea a bit bitter? It is the role of catechins. In animal studies, catechins have been found to lower blood pressure, protect vascular endothelial cells, reduce oxidative stress, reduce inflammation, and improve blood lipid distribution. So, the catechins in tea are a good thing. Of course, the caffeine content in green tea is much lower than coffee, an 8-ounce cup of green tea only has 25 mg of caffeine, while an 8-ounce cup of coffee contains 95-165 mg of caffeine, so a cup of coffee contains 3-6 times more caffeine than a cup of green tea.
Why drink green tea? For people with high blood pressure, drinking green tea is safer. In general, a person should not exceed 400 mg of caffeine a day, which is actually a lot of money. For people with high blood pressure, whether it is generally high or severely high, I would never recommend drinking coffee. Because this will only increase the risk of death, and this is a process of quantitative change to qualitative change, why bother with yourself?
From the perspective of Chinese medicine, how do you look at coffee and green tea? From a TCM perspective, they are even more different. Because coffee is not a part of traditional Chinese medicine, people don't know how to judge it. But by its effect on the human body, it can be roughly classified. For example, drinking coffee will increase the heart rate and blood pressure, which are both thermal and positive, so it can be said that coffee is hot. Whereas, green tea itself is cold, so they have different properties.
In addition, caffeine acts as a diuretic and obviously has an effect on our kidneys, depleting kidney essence. In addition, high blood pressure is a function problem of the liver from the perspective of traditional Chinese medicine, and coffee can cause people to be irritable, etc., which are related to our liver, so to speak, it enters the liver meridian and kidney essence.
So, from the perspective of Chinese medicine, who is not suitable for coffee? It is a person who has a prosperous liver, a deficiency of yin in the liver and kidney, and an hyperactivity of the liver yang. Hyperactivity of liver yang is a very common TCM syndrome differentiation result in hypertension in Western medicine. A large part of the hypertension mentioned in Western medicine is the hyperactivity of liver yang mentioned in traditional Chinese medicine. Therefore, people with hyperactive liver should drink less coffee.
Okay, let's wrap up today's content. For people with severe high blood pressure, try to drink as little coffee as possible, and choose green tea instead, which will reduce the risk of death from heart disease. If you have any experiences and insights in this area, please share them with me in the comment area. I'm nutritionist Wang Yan, concerned about health, we'll see you in the next episode.