Negative Effects of Drinking Tea
Tea comes in various forms, with the most popular being black tea, green tea, white tea, and oolong tea (Chinese black tea). This article outlines the potential harms associated with the consumption of each type, as well as the general risks linked to excessive tea intake.
Negative Effects of Black Tea
Safety Profile of Black Tea
Moderate consumption of black tea is generally considered safe for most adults. During pregnancy and breastfeeding, it is advisable for mothers to limit their intake to no more than two cups per day, as this amount contains approximately 200 milligrams of caffeine. Higher caffeine consumption during pregnancy could be associated with an increased risk of miscarriage, sudden infant death syndrome, and several other adverse effects, including withdrawal symptoms in newborns and lower birth weight.
For breastfeeding mothers, drinking more than three cups of black tea daily may irritate the baby and increase bowel movements. In contrast, moderate consumption of black tea is likely safe for children when mixed with food.
Warnings Associated with Black Tea
There are several risks and precautions related to the use of black tea, including:
- Potential Contaminants: All brewed teas may contain harmful heavy metals like lead and aluminum, which can be toxic in large quantities. Some teas might also contain trace amounts of arsenic and cadmium, though these levels are typically not harmful. Black tea is known to contain high levels of manganese, which is beneficial in moderate amounts but can be toxic in excess. The risk of these contaminants increases with longer steeping times; thus, limiting steeping to three minutes can reduce these hazards.
- Increased Risk of Iron Deficiency: Black tea contains tannins, which can impair iron absorption. A 2017 review published in Current Developments in Nutrition indicated that continuous consumption of tannic acid may decrease the bioavailability of iron. Individuals with a history of iron deficiency should avoid consuming black tea along with iron supplements or high-iron meals and should allow a one-hour interval between eating and drinking black tea.
- Hormone-Sensitive Conditions: Those with conditions such as breast cancer, uterine cancer, ovarian cancer, endometrial cancer, and fibroids may want to avoid black tea, as it may have estrogen-like properties that could exacerbate these health issues.
Negative Effects of Green Tea
Safety Profile of Green Tea
Green tea is generally safe for most healthy adults when consumed in moderate amounts, approximately eight cups per day. Moderate green tea consumption is likely safe for children within the common amounts found in food and beverages. However, there is limited information regarding the safety of green tea extracts for children, and some reports link them to liver damage in adults. Thus, experts recommend against green tea extract consumption by individuals under 18. Pregnant and breastfeeding women should adhere to the precautions outlined for black tea.
Warnings Associated with Green Tea
The following warnings are related to green tea consumption:
- Anemia: Drinking green tea may worsen anemia symptoms.
- Glaucoma: Green tea consumption could increase intraocular pressure, peaking within 30 minutes and lasting at least 90 minutes.
- Liver Conditions: Green tea extracts have been linked to instances of liver damage and may worsen conditions in individuals with liver diseases.
- Osteoporosis: Green tea could enhance calcium excretion in urine; hence, individuals should limit caffeine intake to less than 300 milligrams daily, equivalent to 2-3 cups of green tea. Calcium supplements can help counterbalance the calcium loss caused by caffeine.
Negative Effects of White Tea
Safety Profile of White Tea
Some commercially available white teas in tea bags may contain lead. Studies indicate that certain retail teas have unsafe lead levels for pregnant and breastfeeding women.
Warnings Associated with White Tea
White tea generally has lower caffeine levels compared to other types such as green and black tea. However, caffeine content can vary based on tea plant type and cultivation location. All caffeinated beverages can lead to a range of side effects in some individuals.
Negative Effects of Chinese Tea
Safety Profile of Chinese Tea
Chinese tea is generally safe for most healthy adults when consumed in moderate amounts, about four cups a day. For pregnant and nursing women, consuming up to three cups or fewer is likely safe. Higher amounts may have negative effects on both the mother and the fetus due to caffeine content. Additionally, consumption of Chinese tea in food portions is deemed safe for children.
Warnings Associated with Chinese Tea
Drinking Chinese tea might increase the amount of calcium excreted in urine, potentially weakening bones. Therefore, individuals with osteoporosis should limit their intake to no more than three cups daily.
Side Effects of Excessive Tea Consumption
Most individuals can enjoy 3-4 cups or between 710-950 milliliters of tea daily without experiencing negative side effects. However, some people may face challenges even with lower amounts. Common side effects are primarily attributed to the caffeine and tannin content in tea, which may affect individuals differently. Here are several potential adverse effects of consuming high amounts of tea:
- Caffeine-Related Effects: Excessive tea consumption can adversely affect health due to its caffeine content. Symptoms from high caffeine intake may include dehydration, insomnia, anxiety, hand tremors, elevated body temperature, dizziness, headaches, increased heart rate, irritability, and a cycle of energy followed by fatigue. Additionally, high doses of caffeine may worsen conditions such as diabetes, hypertension, glaucoma, and irritable bowel syndrome.
Some individuals may also experience caffeine withdrawal symptoms, as caffeine is an addictive stimulant. Regular consumption from tea or other sources can lead to dependence, with withdrawal manifestations including headaches, irritability, increased heart rate, and fatigue. The quantity of caffeine and the duration of exposure required to develop dependency can vary significantly across individuals. However, some studies indicate dependency can start after just three continuous days of caffeine consumption, with severity increasing over time.
- Tannin-Related Side Effects: Tannins, responsible for tea’s astringent flavor, may cause nausea, especially when consumed in large amounts or on an empty stomach. This astringent nature may irritate the digestive tract, leading to uncomfortable symptoms like nausea and stomach pain. If nausea occurs after drinking tea, it is advisable to reduce overall consumption. Adding a bit of milk or consuming food alongside tea may alleviate these symptoms.
Are There Risks Associated with Drinking Tea on an Empty Stomach?
Scientific evidence regarding the impact of consuming tea on an empty stomach is limited. However, a systematic review published in Drug Safety in 2008 noted that concentrated green tea extracts taken on an empty stomach could result in more harmful effects compared to consumption with or after meals.
For more detailed information, please refer to the article on the effects of consuming tea on an empty stomach.
Recommended Tea Consumption Levels
Research results regarding the optimal amounts of tea consumption remain inconclusive. Most likely, healthy adults can safely consume up to 400 milligrams of caffeine daily. Although moderate tea consumption is a healthy choice for many, exceeding 3-4 cups daily may lead to adverse side effects. For children, daily caffeine consumption should not surpass 100 milligrams. Pregnant and breastfeeding women are advised to limit daily caffeine intake to 200 milligrams or less and should consult with healthcare professionals regarding caffeine use in light of their health conditions.
Benefits of Drinking Tea
Tea is rich in flavonoids, potent antioxidants that may help mitigate damage caused by harmful free radicals, which are associated with increased risks of cancer and cardiovascular diseases. One of the most powerful antioxidants found in tea is epigallocatechin gallate (EGCG). Additionally, decaffeinated teas and herbal teas contain trace amounts of essential minerals such as potassium, phosphorus, magnesium, sodium, copper, and zinc, although actual concentrations vary based on the tea plant’s age and growth conditions.
For more information on the benefits of tea, feel free to read the article detailing the benefits and risks associated with tea consumption.
Overview of Tea
Tea ranks as one of the most popular beverages globally, consumed by two-thirds of the world’s population. This drink is derived from the leaves of the Chinese camellia plant (scientific name: Camellia sinensis) and is categorized based on the processing of the tea leaves and the timing of the harvest into black (fermented), green (unfermented), and oolong (semi-fermented) teas. These types differ due to the drying and fermentation processes employed, which define their chemical composition. For instance, green tea is produced using young tea leaves, which are consumed without fermentation after withering, steaming, and drying.
As a general recommendation, avoid purchasing expensive packaged teas that may contain added sweeteners. To enjoy the benefits of tea more effectively, it is advisable to prepare it at home, served hot or iced.