Harmful effects of excessive tea intake

Despite the benefits of tea, despite the lack of severity compared with coffee in terms of the percentage difference of caffeine, the tea becomes harmful in the following cases: -

1 - excessive Intake: -
Which causes ulcers in the stomach and duodenum.

2 - if boiled so much that it turns its color to dark brown: -
Which causes the heart muscle disorder, constipation and laziness of the digestive system.

3 - If taken immediately after having meal: -
Which causes difficulty in digestion, so I prefer to take tea an hour after having meal.

4 - If you take tea on an empty stomach (empty stomach ): -
Which may destroy mucosa of stomach and duodenum with follow up complications.

5 - Patients with kidney stones and patients with gastric ulcers or duodenal ulcers should be careful about taking tea. Excessive intake may be harmful for them.