Caffeine is a very powerful drug (alkaloid) acting as a stimulant to the nervous system, the heart, the lungs and the kidneys.Most of its effects on the body are produced through its action on the nervous system, but its harmful effect on the heart results directly from its poisonous effect on the heart muscle.
Small doses stimulate and alert the nervous system to activity and increase heart action.But larger doses taken often cause a rapid heartbeat to remain permanently, and later there are irregularity and jumpy contractions, indicating fibrillation - which means permanent heart damage.
Caffeine injures the heart muscle even more than digitalis, and by causing contraction of the blood vessels it makes the blood pressure rise.Large doses taken often have an even more dangerous effect, causing pain and fullness in the head ,restlessness,confusion, insomnia,ringing in the ears,disturbance of vision,tremor and hallucinations.
The caffeine in coffee, the theine in tea, the alkaloids (theobromin) in chocolate and cocoa-all are of the same nature, have the same effect on the heart and nervous system, and should only be used as drugs in emergencies.
Coffee has a volatile oil in it which,when taken in small amounts, acts as a stimulant to the appetite and as a laxative. But taking coffee too often leads to indigestion, heartburn and hyperacidity.
Tea produces chronic constipation and indigestion, because of the tannin (tannin acid ) it contains so that the scant benefit certainly doesn't repay for the irreparable damage perpetrated by these drinks.
Tea, coffee and soft drinks (cola drinks) relying on similar drugs, seem to pep you up, but they are not ultimately conducive to good health and should not be imbibed indiscriminately or frequently, if at all