Stomach Problems: The tannins present in the green tea increase the stomach acid which may cause stomach ache, nauseous feeling, or cause constipation. Thus, green tea is not consumed on an empty stomach . It is best to drink green tea after a meal or in-between meals.
Is it bad to have too much green tea?
If you are sensitive to caffeine, or suffer from insomnia, 10 cups of green tea is probably going to be too much for your system, regardless of the benefits. Green tea can also interfere with the absorption of iron, too, so it's recommended that you avoid drinking green tea with meals and just drink it between them.
Is green tea healthy for you?
What's good for the heart is usually good for the brain; your brain needs healthy blood vessels, too. Green tea seems to help keep blood sugar stable in people with diabetes. Because catechins lower cholesterol and blood pressure, they can help protect against the damage a high-fat diet can cause, Ochner says.