Ordinary healthy people can drink tea properly, but avoid drinking strong tea on an empty stomach or drinking tea before going to bed. Drinking strong tea on an empty stomach can easily lead to palpitation, dizziness, weakness of limbs and other drunken tea phenomena. Drinking tea before going to bed can easily lead to insomnia. These are all due to caffeine's functions of exciting the nerve center of the brain and promoting cardiac hyperfunction.
Patients with certain diseases should not drink tea. Tannic acid in tea affects the body's perspiration and hinders the body's normal heat dissipation. It is not recommended for patients with fever to drink tea. Theophylline, tea polyphenols and other substances in tea have certain irritation to the gastrointestinal tract, which is easy to aggravate gastrointestinal symptoms, such as nausea, vomiting and diarrhea. Caffeine in tea has the function of exciting the nerve center, and it is easy for neurasthenia patients to lose sleep when drinking tea. The combination of tannic acid and iron in tea will form insoluble substances, which will hinder the absorption of iron in the body and is not good for anemia patients. Urinary calculi are usually calcium oxalate stones, and tea contains oxalic acid, which will combine with calcium during metabolism and aggravate stones. Caffeine can promote cardiac hyperfunction, and patients with coronary heart disease will increase the probability of heart attack.
Breast-feeding new mothers should not drink tea, caffeine is easy to cause insomnia, and it is easy to cause intestinal spasm and crying for no reason after being secreted to the baby through milk.