Srila Prabhupäda: The Vaisñava philosophy teaches that we should not even kill plants unnecessarily. In the Bhagavad-gitä (9.26) Krsna says:
patram puñpam phalam toyam
yo me bhaktyä prayacchati
tad aham bhakty-upahåtam
“If someone offers Me with love and devotion a leaf, a flower, a fruit, or a little water, I will accept it.” We offer Krsna only the kind of food He demands, and then we eat the remnants. If offering vegetarian food to Krsna were sinful, then it would be Krsna’s sin, not ours. But God is apäpa-viddha—sinful reactions are not applicable to Him. He is like the sun, which is so powerful that it can purify even urine—something impossible for us to do. Krsna is also like a king, who may order a murderer to be hanged but who himself is beyond punishment because he is very powerful. Eating food first offered to the Lord is also something like a soldier’s killing during wartime. In a war, when the commander orders a man to attack, the obedient soldier who kills the enemy will get a medal. But if the same soldier kills someone on his own, he will be punished. Similarly, when we eat only prasäda [the remnants of food offered to Krsna], we do not commit any sin. This is confirmed in the Bhagavad-gitä (3.13):...