The Alzheimer's Society commented that "this study adds to previous research that suggests green tea might help to reduce the risk of Alzheimer's disease. However, the researchers used a far higher dose of the active green tea chemical than would ever be found in the human body. More research is needed to see whether green tea is protective at a much lower dose, and to understand the mechanism involved."
Cardiovascular diseases, which lump heart disease, stroke, and other diseases of the heart and blood vessels caused by atherosclerosis and hypertension (high blood pressure) into one category, are the most prevalent causes of death in the world. Studies show that green tea can improve some of the main risk factors for these diseases, which includes helping regulate total cholesterol, LDL cholesterol, and triglycerides. One method by which green tea might help: it significantly increases the antioxidant levels of your blood, protecting LDL cholesterol particles from oxidation—one of the causes of heart disease.
Rooibos tea is anti-inflammatory in nature, which means that it reduces blood pressure and scavenges free radicals like other antioxidants. Quercetin, another powerful antioxidant found in rooibos tea, has been linked to preventing a wide variety of heart conditions. It promotes an increase in HDL cholesterol (good cholesterol) and inhibits the LDL cholesterol (bad cholesterol) from binding to the walls of arteries and blood vessels.