Does anyone know of any studies on diet vs. violence in American, especially on serial or mass murder?

OK, all this "blame guns", "blame the media", "blame music/TV", "blame race", etc, talk on mass murder and mass shootings got my family talking at home on random violence in America.

We narrowed the violence to common factors: young American men. You don't see women mass shooters.

This got us thinking, is it a hormone imbalance? Too much testosterone, or too little? Instability in young men's brain chemistry? Etc.

We breed and raise fish, and often look to them for insight into natural instinct and group behavior. It is well known to us that you take a group of fish, and feed them a high protein diet, and you can increase aggression and mating desire. Give the fish enough space and females, and aggression can be lower and they exist peacefully. Reduce space, limit females, etc, and suddenly you have a bunch of male fish warring with all other fish in the tank, killing baby fish, and just generally going on a rampage. Further,it is known that America is a heavy beef and milk consuming country and we also pump the cows full of hormones, steroids, antibiotics, etc. Take the two observations in combination, and one wonders if the diet is a factor in the violence in these young men.

We were wondering if any studies have been done on the killers' diets. Any vegetarian mass killers? Are they heavy meat eaters? Any blood tests and blood chemistry data?

Could the violence trend have a link to diet? If we as Americans adjusted our food culture, could the violence be reduced?

Sure things like gun control can limit access to the weapon, but the cause of the violence is not address and people can find alternative ways to mass murder (poison, bombs, etc). But why not look at why random young men snap and want to murder.