High blood pressure, or hypertension, is a serious health problem that may cause a stroke or heart attack if left untreated. A normal blood pressure reading is 120/80 mmHg; if your blood pressure is consistently 160/100 mmHg or above, your doctor will likely prescribe anti-hypertensive medicines to help get your blood pressure down into the normal range. Losing weight, eating a low-sodium diet and getting plenty of exercise can also help lower your blood pressure. Green tea may also bring your blood pressure down, but scientific evidence to show it works is limited. Do not use it in place of medicines prescribed by your doctor.
Properties
Green tea is a commonly-consumed beverage made from the leaves of the Camellia sinensis that is also used to treat a variety of medical ailments including cancer, cardiovascular disease and hypertension. It contains a number of biologically-active compounds including a polyphenol known as epigallocatechin-3-gallate, or ECGC. According to the Memorial Sloan-Kettering Cancer Research, ECGC may help to lower blood pressure by modulating vascular constriction.
Efficacy
The results of a study by M.A. Potenza and colleagues, published in the May 2007 issue of the "American Journal of Physiology, Endocrinology and Metabolism," show that EGCG lowers systolic blood pressure, although the study was carried out in hypertensive rats, not in people with high blood pressure. However, the results of an earlier study by Y.C. Yang and colleagues, published in the July 2006 issue of the "Archives of Internal Medicine," found that habitual consumption of green tea significantly reduces the risk of developing hypertension. MedlinePlus notes, however, that the caffeine in green tea may actually increase blood pressure but adds this is unlikely to occur in people who regularly drink green tea or other caffeinated drinks.
Side Effects and Contraindications
Green tea is likely safe for most adults, according to MedlinePlus, but drinking more than five cups a day may cause side effects, including headache, sleep problems, vomiting, irritability, heartburn and confusion. It may also inhibit iron absorption. Green tea is contraindicated in many conditions, including diabetes, bleeding disorders, heart conditions, anxiety disorders and anemia. It also interacts with a number of drugs, such as lithium, birth control pills, warfarin and antibiotics.
Other Herbal Options
Other herbs may also help lower high blood pressure, notes the University of Maryland Medical Center. These include reishi mushroom, hibiscus and garlic, although UMMC adds that more research is needed to prove that they are effective. Like green tea, these herbs may not be suitable for everyone and may cause side effects. For example, garlic is not suitable for people suffering from a bleeding disorder or HIV, while reishi mushrooms may cause dizziness and gastrointestinal upset. Ask your doctor for advice before using them.
References
- netdoctor: High Blood Pressure (Hypertension)
- Memorial Sloan Kettering Cancer Center: Green Tea
- PubMed: EGCG, a Green Tea Polyphenol, Improves Endothelial Function and Insulin Sensitivity, Reduces Blood Pressure, and Protects Against Myocardial I/R Injury in SHR
- PubMed: The Protective Effect of Habitual Tea Consumption on Hypertension
- MedlinePlus: Green Tea
- RxList: Garlic
