What are the health risks of Chinese tea?

Chinese tea is loved worldwide for its unique flavors and potential health benefits. However, excessive or improper consumption of tea may also lead to some health risks. Below is a detailed analysis of potential health issues related to long-term tea consumption.

1. Nutrient Absorption Interference

(a) Impairment of Iron Absorption

Tea contains a significant amount of tannins, especially in unfermented green tea. When tannins enter the body, they can bind with iron in food, forming insoluble tannin-iron complexes that block iron absorption. For individuals with iron-deficiency anemia or inadequate iron intake, consuming large amounts of tea regularly may worsen the deficiency, leading to symptoms like dizziness, fatigue, and pale skin. For example, drinking tea immediately after meals increases the likelihood of iron binding with tannins, further hindering iron absorption.

(b) Disruption of Calcium Absorption

Long-term tea drinking may also impact calcium absorption. Caffeine in tea has a diuretic effect, leading to the loss of calcium through urine. Additionally, tannins can combine with calcium to form insoluble calcium salts, decreasing its absorption. For older adults or growing children, reduced calcium absorption could increase the risk of osteoporosis or poor bone development. If calcium intake is already insufficient, excessive tea consumption may exacerbate calcium deficiency.

2. Adverse Effects on the Gastrointestinal System

(a) Stomach Irritation

The caffeine and polyphenols in tea can irritate the stomach lining, especially when consumed on an empty stomach or in concentrated forms. Drinking strong tea on an empty stomach for prolonged periods can lead to excessive stomach acid secretion, resulting in discomfort such as stomach pain, bloating, and acid reflux. For individuals with pre-existing conditions like ulcers or gastritis, improper tea consumption can worsen these issues and hinder the healing process.

(b) Impact on Digestion

Caffeine in tea stimulates gastric acid secretion and enhances bowel movement. In moderation, this can aid digestion, but excessive tea consumption, particularly after meals, may dilute gastric juices and disrupt normal digestion. Overindulging in tea may cause gastrointestinal disorders like indigestion and diarrhea. For instance, while pu-erh tea (普洱茶) has some digestive benefits, excessive intake can lead to stomach discomfort.

3. Effects on Sleep Quality

(a) Caffeine Stimulation

Tea generally contains caffeine, a central nervous system stimulant. Drinking tea before bed, especially strong tea or tea with higher caffeine content (e.g., black tea (红茶), oolong tea (乌龙茶)), can make it difficult to relax and fall asleep. The stimulating effect of caffeine on the brain leads to sleep disturbances, such as insomnia, shallow sleep, and frequent dreams. People with poor sleep quality or insomnia may find that drinking tea before bed worsens these symptoms, affecting their energy levels and productivity the next day.

(b) Disruption of the Biological Clock

Irregular tea-drinking habits, such as frequent tea consumption at night, can disrupt the body’s natural biological clock. This can lead to sleep disorders, and even after stopping night-time tea drinking, it may take time for the body’s sleep rhythm to normalize. This not only affects sleep quality but may also have negative long-term health impacts.

4. Other Potential Risks

(a) Increased Risk of Tooth Discoloration

Tea contains polyphenols and pigments that can stain teeth over time. Drinking large quantities of tea, especially without proper oral hygiene, can cause these compounds to adhere to the surface of teeth, leading to yellow or black discoloration. People who regularly drink strong tea, such as black tea (红茶) or dark tea (黑茶), are at a higher risk of this. Without proper dental care, the accumulation of tea stains may also lead to tooth decay.

(b) Tea Intoxication (“Drunken Tea” Phenomenon)

“Drunken tea” refers to the symptoms of dizziness, fatigue, nausea, and tremors that occur after consuming large amounts of strong tea in a short period. This is primarily due to an overdose of caffeine and theobromine in tea, which overstimulate the central nervous system and can lower blood sugar. While “drunken tea” usually does not cause long-term harm, it can cause discomfort and affect one’s health and daily life.

5. Other Risks of Excessive Tea Consumption

(a) Caffeine Overload

Tea contains caffeine, and excessive intake can lead to symptoms like insomnia, anxiety, palpitations, and gastrointestinal discomfort. Individuals vary in their tolerance to caffeine, so some people may be more sensitive to it.

(b) Oral Health Issues

Tannins and pigments in tea can cause tooth staining, forming tea stains. The acidic compounds in tea may also negatively impact oral health, potentially leading to tooth sensitivity.

(c) Herbal Interactions

If tea is consumed alongside herbal medicines or supplements, the compounds in tea may interact with these substances, affecting their absorption, metabolism, or elimination from the body.

(d) Risk of Anemia

The tannins in tea may interfere with the absorption of non-animal-based iron. Regular and excessive tea consumption can increase the risk of iron-deficiency anemia, especially in individuals prone to low iron levels.

(e) Osteoporosis

Excessive tea consumption may affect calcium absorption, which negatively impacts bone health. The polyphenols and oxalates in tea may interfere with calcium uptake, increasing the risk of osteoporosis.

Moderate tea consumption is generally safe and can even be associated with health benefits. However, individual differences, health conditions, and factors such as the type of tea and brewing time can all influence the potential risks. To enjoy tea safely, it is important to avoid excessive consumption, particularly on an empty stomach, and to maintain good oral hygiene. If you have any health concerns or special circumstances, it is advisable to consult with a healthcare professional.