In general, is eating a daily 4 oz. can of tuna fish packed in oil any better than tuna packed in water to try to lower chloresterol? differences?

Great question: That's a very interesting question! it hasn't been studied to my knowledge. On the one hand, fish oil will raise total cholesterol but preferentially raises HDL (good) cholesterol. The adkins diet showed (to everyone's surprise) that eating low carbs (high fat) diet doesn't actually raise cholesterol as was expected. So we don't know! one thing we do know: tuna in oil has more calories than water.