Green tea is often touted as one of the healthiest drink options. As with other types of tea, green tea comes from Camellia sinensis plant leaves. However, compared with black tea, green tea is lower in caffeine and has a high epigallocatechin gallate content. Green tea is certainly healthier than sugary soft drinks, but you still risk side effects from this beverage. Such risks may even include elevated blood pressure, also called hypertension.
Caffeine in Green Tea
The Center for Science in the Public Interest estimates that 8 ounces of green tea contains between 35 and 60 milligrams of caffeine. This is a fraction of the average cup of coffee. The precise amount of caffeine varies between brands and depending on how long you steep the tea. Caffeine acts as a stimulant, boosting mood and increasing alertness. While rare with green tea, too much caffeine can lead to anxiety, tremors and increased heart rate. You may also be more prone to adverse effects if you have caffeine sensitivity, which varies between individuals. This occurs when the body metabolizes caffeine at a below average rate. According to the European Food Information Council, it takes between two and 10 hours to metabolize caffeine, with four hours being the average.
Blood Pressure Effects
Proponents of green tea often suggest that flavonoids in tea leaves may promote heart health and even lower blood pressure. Still, the caffeine content may actually cause a temporary rise in blood pressure because of the rapid rate the body absorbs the substance. A study published in the August 1999 issue of "Journal of Hypertension" reported that tea consumption caused slight increases in blood pressure among study participants. However, the increases were not considered significant enough to raise serious health concerns. What can be garnered from this study is that green tea may not be the most dependable or safest method of blood pressure regulation.
Determine Proper Tea Consumption
Moderate consumption of green tea is unlikely to cause a significant increase in blood pressure. When it comes to green tea, MedlinePlus defines moderate consumption of the beverage as an average of five cups per day, or a total of between 200 and 300 milligrams of caffeine. The caffeine content of green tea makes this drink a better choice for increasing mental alertness if you're worried about higher caffeine sources such as black tea and coffee. There is also the added benefit of the antioxidant epigallocatechin gallate, a catechin that may help prevent free radicals from destroying cells that can lead to chronic diseases. If you're worried about overall caffeine intake and blood pressure, it's important to consume green tea in moderation.
Special Considerations for Caffeine
While the caffeine content of green tea alone may not lead to high blood pressure, you may want to avoid the beverage if you already have this health concern. Children, pregnant women and nursing mothers should refrain from green tea because of the potential for adverse health effects. During pregnancy, the body metabolizes caffeine at a slower rate, so it stays in the body longer. Caffeine has the possibility of leading to birth defects and may be passed through breast milk. Anxiety and hyperactivity can occur in some children from caffeine. To avoid these concerns, consider decaffeinated green tea instead.
- National Center for Complementary and Integrative Health: Green Tea
- MedlinePlus: Caffeine in the Diet
- Journal of Hypertension: Effects on Blood Pressure of Drinking Green and Black Tea
- MedlinePlus: Green Tea
- Center for Science in the Public Interest: Caffeine Content of Food and Drugs
- National Cancer Institute: Tea and Cancer Prevention
- European Food Information Council: Caffeine and Health