New tea refers to tea leaves that have been picked for less than a month. Since these teas haven't been stored for a period of time, some substances that may have adverse effects on the body (such as polyphenols, alcohol compounds, and aldehyde compounds) have not been fully oxidized yet. Drinking new tea for a long time may cause reactions such as abdominal distension and diarrhea. Very fresh tea can irritate the stomach lining, causing gastrointestinal discomfort, and may even exacerbate conditions like insufficient gastric acid or chronic gastric ulcers.
The polyphenols in tea have a certain astringent effect on the gastrointestinal mucosa, so drinking tea may worsen constipation in patients who already suffer from it.
The caffeine in tea has a clear stimulating effect on the cerebral cortex. People suffering from neurasthenia or insomnia will find that drinking tea keeps their brain in an extremely excited state, making it impossible to rest.
The tannic acid in tea can react with...