animals hear the screaming and crying of other animals being slaughtered. these emotions - fear, grief, and rage - produce chemical changes in their bodies. when you eat animal products you are directly consuming all of this negative energy.
Whoever said one person can't make a difference have never met a vegan. EVERYDAY a vegan saves: gallons of water, 45 pounds of grain, 30 square foot of forest land, 20 lbs equivalent and one animal's life.