From what I can see, the research method is quite flawed. What if drinking more coffee or tea makes you die younger? This would result in the same data they ba

From what I can see, the research method is quite flawed. What if drinking more coffee or tea makes you die younger? This would result in the same data they base their conclusions on. E.g. dementia en strokes correlate with age. If you die young because of high coffee consumption you wouldn't show up in the "drank coffee and subsequently had a stroke" group.