Steeping and beneficial effects of tea.

How does steeping tea more than once affect it’s nutritional value? I’m talking in terms of anti oxidants, phenols, etc. I have read that one needs to drink a minimum of 4 cups a day to get the health benefits of tea. Is steeping loose leaf tea more than once costing me the health benefits? I’m a newb to tea, so please bear with me and my ignorance.