Is black tea good for you? A recent study found that black tea is rich in an antioxidant called Flavonoids: which can help stop LDL’s from oxidizing. This basically means it can prevent bad cholesterol for oxidizing. Flavonoids can also be found in purple grape juice, red wine, and onions. Flavonoids were found to help the vascular endothelium work better. The flavonoids help this inner most layer of blood vessels by controlling the blood vessel’s diameter. Doing this makes it easier for the blood vessel to constrict or dilate. Blood vessels expand when the body needs more blood, such as during exercise. Those with cardiovascular disease have blood vessels that don’t work like they are supposed to. This can lead to strokes and heart attacks. Black tea contains caffeine that can affect heart rate and blood pressure. Those with heart problems should avoid consuming too much caffeine.