Yerba mate contains vitamins, minerals, polyphenols and is rich in antioxidants. Yerba Mate leaves also contain saponins. Saponins are phytochemicals that have been found to specifically stimulate the immune system and aid the body in protecting against disease.
   Mate contains xanthines, which are alkaloids in the same family as caffeine, theophylline, and theobromine, well-known stimulants also found in coffee and chocolate. Mate also contains the chemical elements Potassium, Magnesium and Manganese.
   Mate products are sometimes marketed as caffeine-free alternatives to coffee and tea, and said to have fewer negative effects. This is often based on a claim that the primary active xanthine in mate is mateine, said to be a stereoisomer of caffeine. However, caffeine has no stereoisomers. "Mateine" is an official synonym of caffeine in the chemical databases. So please no more emails to say we're wrong about this.
   Researchers have found that yerba mate does contain caffeine, but some people seem to tolerate a mate drink better than tea or coffee. This is expected since their chemicals are different - besides the caffeine.
   Yerba mate's physiological effects are similar to - and yet different from - more common caffeinated beverages like coffee and tea. Users report a mental state of wakefulness, focus and alertness reminiscent of most stimulants, but often remark on mate's unique lack of the negative effects typically created by other such compounds, such as anxiety, diarrhea, jitteriness, and heart palpitations.
   Reasons for mate's unique physiological attributes are beginning to emerge in scientific research. Studies of mate, though very limited, have shown preliminary evidence that the yerba mate xanthine cocktail is different from other plants containing caffeine most significantly in its effects on muscle tissue, as opposed to those on the central nervous system, which are similar to those of other natural stimulants. Mate has been shown to have a relaxing effect on smooth muscle tissue, and a stimulating effect on heart tissue.
   Mate's negative effects are claimed to be of a lesser degree than those of caffeine. Many users report that drinking yerba mate does not prevent them from being able to fall asleep, as is often the case with some more common stimulating beverages, while still enhancing their energy and ability to remain awake at will. However, the net amount of caffeine in one preparation of yerba mate is typically quite high, in large part because the repeated filling of the mate with hot water is able to extract the highly-soluble xanthines extremely effectively. It is for this reason that one mate may be shared among several people and yet produce the desired stimulating effect in all of them.