At the link, you'll find many, many theories, facts and some medical info concerning the "caffeine bean"....
knowfood.cn/en/coffee/%E5%9...
"... The advantages for heart, liver and lungs
The beneficial action of caffeine extends as far as the heart and can therefore be used in pharmacotherapy as a cardiotonic. Furthermore it improves the one of the arteries without altering blood pressure, and also improves coronary circulation. Remember that the action on the heart is secondary, and is not detectable in usual doses of 2-3 cups a day. This is especially true with regard to those that can be classed as negative actions, such as tachycardia.
The lungs also benefit from the stimulating action of a cup of coffee. The dilatation of the bronchi improves, as does lung ventilation, thus facilitating breathing.
At muscular level, coffee improves the capacity for muscular concentration, reduces tiredness, and improves the co-ordination of movements and sporting performance. This is why coffee is recommended to athletes, as it relieves fatigue, especially in sports which require stamina, when fatigue takes over and movements become heavy.
At everyday level it stimulates the vasomotor nerves and therefore facilitates digestion. This makes coffee ideal not only to wake you up first thing in the morning, but also at lunch and dinner, as it goes to work on the stomach lining, encouraging the secretion of gastric juices, initiating and improving the digestive process.
It activates the production of bile in the liver and the contraction of the gall bladder. It aids movement in the intestine, improving its functions. Other positive effects of a good cup of coffee are felt by the kidneys, in which the renal arteries dilate thus improving diuresis..."