Usually prepared tea i.e. preparation through boiling tea leaves, milk and sugar and filteration is harmful. Tanin is released if tea is boiled which harmful to our body.
If you slightly change the method of preparation, then the tea is beneficial. Boil milk, water and sugar in necessary proportions. After the said preparation is boiled, then add tea leaves for 8-10 minutes. Not to boil again with tea. Filter it and drink with some breakfast. Such type of tea preparation is beneficial. You may also use teabags.
You may even add black pepper, cloves, or cardmom to make healthier and tasty.