Drinking green tea is beneficial for lowering cholesterol levels and maintaining mental alertness. The antioxidant in green tea, catechin, is responsible for lowering cholesterol, while caffeine improves mental performance. Drinking tea moderately is safe, although some people experience upset stomach and constipation. Drinking too much can cause other side effects.
Research shows that drinking green tea may possibly be beneficial for individuals with cervical dysplasia, clogged arteries, endometrial cancer, ovarian cancer, Parkinson's disease, osteoporosis, low blood pressure and oral leukoplakia. How the polyphenols in green tea work to cause positive effects is still unexplained as of 2015.
Drinking more than five cups of green tea per day can have varying side effects, which may include headache, vomiting, dizziness, irregular heartbeat, tremors and reduced absorption of iron from foods. Pregnant and breastfeeding women are cautioned against drinking more than two cups of green tea per day. It may increase the risk of miscarriage and caffeine may pass into the breast milk. Other individuals with certain conditions, such as anxiety, anemia, bleeding disorders, glaucoma, liver disease, heart condition and irritable bowel syndrome are warned against drinking too much green tea, as it may worsen their conditions. People who are taking medications should also consult their doctors first to ensure there are no unwanted interaction between green tea and their medication.