The Effects of Tea on Cardiovascular Diseases
Cardiovascular diseases involving the vessels that nourish and surround the heart are referred to as coronary heart disease or coronary artery disease (CAD). When stroke is added to coronary heart disease, the condition is classified as cardiovascular diseases (CVD). It is well known that arterial stiffening in the heart shortens lifespan and contributes to heart and vascular diseases.
Tea is a beverage with a history believed to span around 5,000 years and has become deeply embedded in daily life and culture. The beneficial effects of its active compounds on human health are undeniable. Tea contains numerous chemical substances, including alkaloids, volatile organic compounds, polyphenols, and trace elements. The primary polyphenols in tea are flavanols (catechins) and flavonols.
According to the European Journal of Epidemiology, increased tea consumption is associated with reduced risks of coronary heart disease, cardiac death, myocardial infarction, cerebral infarction, intracerebral hemorrhage, and overall mortality. The polyphenolic compounds in tea exhibit protective effects against chronic diseases. Tea consumption protects against CVD by inhibiting LDL oxidation. Flavonoids in tea neutralize free radicals, prevent the progression of atherosclerotic plaques, and exert antithrombotic effects, thereby offering protection against atherosclerosis. Numerous studies have shown that tea has beneficial effects not only on cardiovascular diseases but also on diabetes, obesity, and cancer.
Different processing techniques yield different types of tea. Unfermented leaves produce green tea, partially fermented leaves produce oolong tea, and fully fermented leaves produce black tea. Among these, white tea undergoes the least processing. While green and black tea are known to benefit human health, white tea contains the highest antioxidant content. Antioxidants neutralize free radicals that damage DNA, harm the body, and accelerate aging. White tea is rich in catechins, particularly EGCG (Epigallocatechin Gallate). The abundant antioxidants in tea inhibit cancer cell growth and exert antibacterial and antiviral effects.
According to the Journal of the American College of Nutrition, regular tea consumption—especially in individuals who have consumed more than 10 grams daily for over six years—provides protective effects against arterial stiffness. Many studies have demonstrated the protective impact of flavonoids in tea on CVD. In a study investigating the protective effect of tea on hypertension, individuals who consumed 120 mL of green or oolong tea daily for more than a year had a significantly reduced risk of hypertension. In a study by Mennen et al. (2003) examining the relationship between cardiovascular risk factors and tea consumption in France, higher daily tea intake in women was associated with lower levels of total cholesterol, serum triglycerides, waist-to-hip ratio, and fasting blood glucose. Quercetin and L-theanine—compounds found in tea—have been shown to lower blood pressure in both animals and humans, thus reducing the risk of developing cardiovascular diseases.
How Should Tea Be Consumed and What Should Be Considered?
Tea is an excellent antioxidant source. Adults are recommended to consume 2–3 liters of fluid per day. Although the primary source should be water, consuming 5–7 cups (800–1120 mL) of tea daily is acceptable. However, caution must be exercised in certain cases. In individuals with heart failure or arrhythmias, tea consumption may cause tachycardia. Excessive tea intake may be harmful in heart failure patients who require fluid restriction. These individuals should consult their physicians to determine a safe daily amount of tea.
Tea may impair iron absorption and contribute to anemia; therefore, individuals with heart failure and anemia should take special care. Tea is best consumed at least 30 minutes after meals—preferably 1 hour later. Excessively hot tea may cause esophageal and gastric ulcers and may even increase the risk of cancer in these areas. Individuals with diabetes should avoid adding sugar to tea, and those with obesity should remember that added sugar contributes unnecessary calories.
