Black tea/milk tea can be unhealthy on some occasions.

 

Side effects vary from gastric problems to severe complications like Anaemia and Alzheimer's disease in some people.
 

Black tea and milk tea are essential beverages in our daily life. The reality of their health benefits is valid and scientifically proven. Tea has numerous disease-fighting capabilities, like anticancer, neuroprotective, cholesterol-lowering, and prevention of cardiovascular diseases due to specific compounds it contains, especially polyphenols, which are antioxidants.

Likewise, the presence of L-theanine in tea also provides antidepressant and mind relaxation properties (1). Although the number of tea benefits is uncountable, it tends to be harmful on specific occasions when taken at an inappropriate time.
 

Iron absorption problem: Causing Anaemia

On certain occasions, tea intervenes in our normal body functions. For example, tea consumption with a meal or just after the meal-eating reduces the absorption of non-heme iron into our body due to tannins, organic substances, in black tea (2).

Remember, the non-heme iron, a plant-based iron, makes 85-90 % of our iron intake while 10-15 % of it is heme iron, an animal-based iron (3). Don't forget that our body uses iron to synthesize a protein called haemoglobin, a part of our Red Blood Cells (RBCs), which helps transport oxygen in our body.

 Unfortunately, black tea decreases the non-heme iron absorption by 79-94%, which is non-acceptable in any way as this can lead to Anaemia (4). 

Causing neurological diseases in People suffering from Kidney defects

Unfortunately, the tea plant has a high capacity to accumulate Aluminium (Al), a neurotoxin, from the soil, which causes many neurological diseases like Alzheimer's disease.

 People with Kidney problems can get Aluminium in their bodies due to their weakened or impaired blood filtration system, leading to neurological disorders (5). 

Interruption of calcium absorption and weakness of bones

High Aluminium content in the body also interferes with other essential metal absorption and metabolism such as Calcium (Ca). It interrupts mineralization and bone growth, leading to impaired body metabolism and fragile bones (6, 7).

Excessive use of tea may cause heartburn and stomach acidity

Caffeine is the crucial ingredient of black tea, which can cause heartburn and stomach acidity. Some research indicated that caffeine relaxes the sphincter that separates the oesophagus from the stomach, permitting stomach acid content into the oesophagus, causing a sensation of heartburn(8).

Affecting sleep cycle

Due to caffeine in tea, excessive intake may disturb your sleep. According to some research, caffeine may inhibit melatonin production, resulting in poor sleep quality, where melatonin is a hormone that helps in sleeping (9).

Toxic metals Risk

Some research suggests that tea contains certain elements, e.g., aluminium, arsenic, cobalt, barium, cadmium, strontium, and nickel, which could harm the human body. Another study showed that excessive tea intake could increase the arsenic concentrations in the body at a level corresponding to moderately high carcinogenic risk (10).

Gastrointestinal Tract Cancer Risk

Cancers of the upper gastrointestinal tract, primarily oral and pharyngeal cancers, are serious health threats to humans and account for nearly 18% of the total worldwide cancer disease (11). Research suggests that consuming hot tea in large amounts directly relates to upper digestive tract cancer. (12).

During a study, people were found more vulnerable to pharyngeal cancer when individuals drank over 3-5 cups of tea in a day than those who consumed two or fewer cups of hot tea per day ( 13, 14 ).

Anticoagulant drugs can't work with tea

Sometimes black tea or even green tea can be harmful. For example, green tea is a significant vitamin K source, which can negatively affect anticoagulant drugs such as warfarin in patients where the medication is urgently needed.

Unfortunately, vitamin K limits the impact of warfarin and reduces anticoagulation in patients (15).

Research suggests that adding lemon to the meal can alleviate tea's negative effect on iron absorption. In this way, lemon may increase iron absorption no matter one may use tea after that.

 

How Can You Avoid The Adverse Effects Of Black tea/Milk tea?

• Research suggests that adding lemon to the meal can alleviate tea's negative effect on iron absorption. In this way, lemon may increase iron absorption no matter one may use tea after that.
• The second way to avoid tea's adverse effects on iron absorption is to consume tea between meals, not just after the meal (16). It will help the digestive system digest the meal properly, and then the body will absorb all the nutrients, including iron.
• Patients with kidney diseases should reduce their intake of black tea to protect themselves from neurological disorders and bone diseases.
• Excessive use of black tea means a high intake of caffeine, which upset the digestive system in the form of stomach discomfort and heartburn and can also disturb the sleeping cycle. The best thing to prevent these issues is to reduce tea consumption.
• Usually, just before going to bed, it is unhealthy to take tea because it can affect your sleep.
• Some people are habitual to taking hot tea, which can cause upper digestive tract cancer, as proved by the research. The healthy way is to let the tea cool down for a while, then take it.
• Tea can negatively affect anticoagulant drugs and be dangerous for patients who have some blood clot issues. These patients should wait for a while after taking pills or even reduce tea consumption.