Green tea can be considered a "national drink" in Vietnam, enjoyed by almost everyone. It is one of the healthiest beverages, packed with antioxidants that help prevent cellular damage, reduce the risk of heart disease, cancer, and slow down aging. In particular, green tea contains caffeine, which keeps the mind alert and fights stress. Additionally, the phenolic compounds in green tea aid in detoxifying the liver and improving digestion.
However, green tea is not a drink that can be consumed casually. If used incorrectly, it can become a health risk and even pose life-threatening dangers. Below are three types of green tea consumption that have been warned against by health experts, yet many Vietnamese continue to make these mistakes.
According to Dr. Le Thi Hai (Former Director of the Nutrition Consultation Center at the National Institute of Nutrition), it is best to consume green tea within the same day. If there is leftover tea, it should be discarded rather than consumed the next day, as it may produce harmful substances for the body.
Additionally, Dr. Le Thi Hai advises against drinking green tea too close to bedtime since the caffeine can make it harder to fall asleep. Green tea should also not be used to take medications, as its active compounds can reduce the effectiveness of the medicine.
Furthermore, it's recommended to limit green tea consumption to 1-2 cups per day.
- Harmful to the Kidneys
According to the Chinese publication Abloluowang, strong tea contains high levels of fluoride, which can be harmful to the kidneys if consumed regularly. The kidneys are the primary organs responsible for excreting fluoride, and when fluoride intake exceeds the kidneys' capacity to expel it, it accumulates in the body and impairs kidney function.
Additionally, strong tea contains high levels of theophylline, which can be particularly harmful when consumed after drinking alcohol. The diuretic effect of theophylline can cause tea and alcohol to be processed simultaneously by the kidneys, potentially leading to organ damage.
- Harmful to the Stomach
Strong tea is high in caffeine and theophylline, which can irritate the stomach lining and increase acid production. Over time, this can damage the stomach lining, leading to conditions such as gastric ulcers. Surveys in China indicate that about 70% of gastric ulcer patients tend to drink strong tea.
- Causes Insomnia
While green tea is effective in managing high blood pressure, strong tea can overstimulate the brain, causing restlessness and insomnia. Additionally, caffeine can accelerate the heart rate, potentially leading to arrhythmias, a condition particularly dangerous for the elderly and those with coronary heart disease.
- Causes Nutritional Deficienc
Strong tea is rich in tannic acid, which interferes with iron absorption, potentially leading to iron-deficiency anemia. It can also interact with proteins and vitamin B1 in food, causing constipation. Nutritional experts have found that excessive tea consumption can increase urination frequency, leading to a loss of important nutrients like magnesium and potassium.
The International Agency for Research on Cancer (IARC) under WHO has classified beverages above 65°C as Group 2A carcinogens. According to IARC, consuming overly hot beverages like tea or coffee increases the risk of esophageal, oral cavity, and throat cancer because the high temperature can damage these organs. Additionally, hot food can harm the digestive system and intestines.
CNN once reported a study conducted on more than 50,000 people, showing that drinking over 700ml of tea at 60°C daily increases the risk of esophageal cancer by 90%.
In reality, many Vietnamese people have the habit of brewing tea with boiling water at 100°C. The mucous lining of the esophagus is very sensitive and easily damaged. Although consuming hot beverages over 65°C occasionally might not cause harm, repeated damage over time can lead to esophageal cancer.
