Drinking the Wrong Tea Can Cause Cancer - How Many Steepings Are Most Dangerous?

Wang Xingguo, Director of the Nutrition Department at Dalian Central Hospital, answers: Tea drinkers can easily feel tea's effect on the stomach and intestines: getting hungry faster. This is because tea leaves contain complex components like caffeine, theophylline, and theobromine, which significantly stimulate gastric acid secretion and promote gastrointestinal motility. Increased gastric acid secretion (and faster gastrointestinal movement) aids food digestion, creating a feeling of "removing fat and relieving greasiness" or getting hungry faster.

However, one must not mistake "removing fat and relieving greasiness" or "hunger" for weight loss. Drinking tea only changes the process and sensation of digestion, not the outcome. The energy you consume from three meals a day—whether carbohydrates, protein, or fat—will not disappear because you drank tea. Clearly, drinking tea does not change your food intake or the composition of your waste; it only alters the digestive process from food to waste. How could this lead to weight loss?

Pu'er tea and black tea have a stronger effect on stimulating gastric acid secretion than green tea, so drinking Pu'er tea更容易 leads to hunger. I have seen people endure stomach pain (related to increased gastric acid secretion damaging the gastric mucosa) while drinking Pu'er for weight loss. Others try to infer tea's weight loss effect from caffeine's stimulant作用. Caffeine increases alertness and basal metabolic energy expenditure, thus aiding weight loss. Caffeine does make one more energetic and enhances athletic ability, but its impact on basal metabolism is minimal. Therefore, tea, coffee, and caffeinated beverages are insufficient for achieving weight loss.

Unfinished Tea Most Likely Forms Tea Scale

Scientific research indicates that drinking water contains minerals and trace amounts of harmful heavy metal ions, such as cadmium, mercury, and arsenic. When water is heated, as the temperature rises, the solubility of certain calcium and magnesium ions decreases, and the concentration of insoluble salts continuously increases. When the water is concentrated to a certain extent, precipitates form. These precipitates can enter the teacup when water is used to brew tea. Tea that is not finished or left exposed to air for a long time allows the tea polyphenols in the leaves to oxidize with the metal elements in the tea stain, producing brown tea scale, commonly known as tea stain, which adheres to the inner wall of the cup. This tea scale contains various harmful metals like cadmium, lead, mercury, and arsenic, making it the chief culprit危害人体健康.

Tea Bags Are Best Steeped Only Once; Loose-Leaf Tea Should Not Exceed 3 Times

Besides tea scale being unclear有害健康, how many times tea should be steeped for maximum nutrition and health is also not clear to many people.

Some people in daily life like to steep tea repeatedly until the flavor is gone. Others steep it only once or twice before changing the leaves. Which method is correct? How many times is best to steep a cup of tea? Yin Junfeng, Associate Researcher at the Tea Research Institute of the Chinese Academy of Agricultural Sciences, says that while the number of steepings is related to personal taste—some prefer weak tea, others strong tea—from a nutrient absorption perspective, tea bags are best steeped only once, and loose-leaf tea should not exceed three times.

He explains that tea contains nutrients such as tea polyphenols (which have cancer-inhibiting effects), tea polysaccharides (which can lower blood sugar), caffeine (which stimulates the central nervous system), and various amino acids and vitamins. How much of these nutrients are released depends greatly on the number of steepings. Generally, the larger the particle size of the tea leaves, the slower the release of nutrients; the smaller the particles, the faster the release.

Compared to loose-leaf tea, the leaves in tea bags are cut and rolled during processing, thoroughly破坏叶细胞. The particle size is relatively small. About 80%-90% of the nutrients in the tea are released during the first 3-5 minute steep. After the second steeping, the remaining roughly 10% of nutrients are also almost全部 released. Therefore, Yin Junfeng suggests that tea bags are best steeped only once. This results in little loss in nutrient absorption and does not affect taste and flavor. Due to their larger particle size, the first steeping of loose-leaf tea should be longer, about 5 minutes, during which 60%-80% of the nutrients are released. After the second steeping, 80%-90% of the nutrients are released. After the third steeping, the leaching rate of nutrients exceeds 95%. Steeping further has little nutritional benefit.

Regarding experts pointing out that multiple steepings can leach harmful substances like pesticides and heavy metals from the tea, Yin Junfeng says this argument has some merit but need not be过分担心. Currently, most pesticides used in tea production in China have extremely low water solubility. Based on每人每天饮茶10克, even steeping tea with a residue of 1 mg/kg, the pesticide intake would be only 0.0001 mg, which is a few thousandths of the daily allowable intake set by the World Health Organization. The leaching rate of heavy metal lead in tea is also relatively low. As long as tea from正规厂家 is purchased, its content will not exceed national standards.

12 Grams Daily Is Most Suitable

Jiang Heyuan, Associate Researcher at the Tea Research Institute of the Chinese Academy of Agricultural Sciences, suggests that for ordinary people, drinking about 12 grams of tea daily, divided into 3-4 steepings, is appropriate. Those who consume more greasy food, smoke, or drink alcohol can适当增加茶叶用量. Pregnant women, children, those with neurasthenia, and those with tachycardia should适当减少饮茶量. Han Chi reminds that with the popularity of Gongfu tea, people are drinking tea "increasingly hotter," which is very wrong. "People drink tea for health, but drinking scalding tea can increase the incidence of cancers like esophageal cancer,得不偿失. The optimal temperature for drinking tea should be around 60°C, not exceeding 70°C."

Additionally, one can drink different teas at different times of the day: a light green tea in the morning to clear the mind; jasmine tea in the morning for fragrance and improved work efficiency; black tea in the afternoon to relieve drowsiness and refresh; and in the evening, when gathering with friends or family, brewing a pot of oolong or Pu'er offers a different情趣 without affecting sleep.