Getting your daily caffeine fix from green tea instead of coffee may help keep you healthy due to the antioxidants, called flavonoids, that this type of tea contains. Since green tea isn't fermented like black tea, it has even more of these beneficial compounds. Research into the health benefits of green tea is still preliminary, so it isn't clear exactly how much you need, and you may need to drink different amounts for different health benefits.
Although cancer levels are lower in some places where people regularly drink green tea, evidence is lacking as to whether green tea can help prevent or treat cancer, according to the American Cancer Society. Some studies show reduced risk for cancer when you drink 3 to 5 cups a day of green tea, while others show either no benefit or an increased risk for cancer. The authors of a review published in the "Cochrane Library" in July 2009 concluded that regularly drinking 3 to 5 cups of green tea per day appears to be safe, but that evidence is too conflicting to give firm recommendations on drinking green tea and any potential link to fighting cancer.
Heart Disease and Stroke
Drinking at least 3 cups of tea per day may help you avoid heart disease, although the reason for this isn't totally clear. Green tea may lower your bad cholesterol and triglycerides while raising your good cholesterol levels, which makes it less likely that your arteries will get clogged. Green tea may also help you lower your blood pressure levels, according to MedlinePlus.
Green tea may also help you control your blood sugar and make you less likely to get Type 2 diabetes, although you need to drink quite a lot -- about 6 cups a day -- to get these benefits. If you do drink this much green tea, at least some of what you drink should be decaffeinated, since more than 5 cups in a day of regular green tea may give you unsafe levels of caffeine, according to MedlinePlus. This may cause you to be more irritable, have trouble sleeping or have an upset stomach.
Drinking green tea is safe as long as you watch how much caffeine you are getting, although some people experience headaches or dizziness when they drink green tea, according to Drugs.com. Some people are more sensitive to caffeine than others, but most people can safely drink between 200 and 300 milligrams per day without adverse effects, according to MayoClinic.com. Each cup of green tea has between 24 and 40 milligrams of caffeine. Talk to your doctor before you start drinking green tea, since it can interact with some medications, including antibiotics, blood thinners and blood pressure medications, either making them less effective or making them more effective and potentially causing side effects.
- University of Maryland Medical Center: Green Tea
- MedlinePlus: Green Tea
- American Cancer Society: Green Tea
- Drugs.com: Green Tea
- MayoClinic.com: Caffeine Content for Coffee, Tea, Soda and More
- MayoClinic.com: Caffeine: How Much Is Too Much?
- The Cochrane Library: Green tea (Camellia Sinensis) for the Prevention of Cancer
Based in Massachusetts, Jessica Bruso has been writing since 2008. She holds a master of science degree in food policy and applied nutrition and a bachelor of arts degree in international relations, both from Tufts University.