Coffee is causing people to be more violent. The reason coffee does this is because of the caffeine. The caffeine blocks diamine oxidase. With the diamine oxidase blocked, the histamine levels rise and accumulate. With the higher histamine levels, the individual then becomes irritated, aggressive, have bad temper.
One reason it does this, is because their zinc levels go down, and the copper rises. Mostly because of the higher level of histamine. They need to stop with the caffeine, they are drinking too much of it. One sign of high levels of histamine, are allergies.
If the histamine levels get high enough, the individual will develop schizophrenia, and also depression.