There are acids in them that are not good for the enamel on your teeth. Small amounts are ok but 6 a day could show your teeth some wear and tear. There are a lot of sugars in them that are bad for your teeth as well. The amount of sugar that you are talking about will be bad for your liver but drinking plenty of water will help with that. Since you drink them a lot you probably dont get the rush (faster heart beat) anymore, but if you do then keeping your heart at a fast rate like that will be hard on it. If you are just looking for the energy and dont really care for the taste I know that Rockstar has a Rockstar Zero, that would be better for you. It comes in a blue can. Even if you drink them for the taste, it might be worth it to try it. I like that taste myself.