Carnivores instinctively eat grass to satisfy their nutritional requirement for vitamin B17. The molecularity of vitamin B17 is 2 parts glucose (sugar), 1 part benzaldehyde, 1 part hydrogen cyanide. B17 is referred to as sugar cyanide. Pure hydrogen cyanide & pure benzaldehyde are deadly poisonous and together (locked in by nature with sugar) become 100 times more deadly poisonous but only to cancer cells as they lack the normal protection that healthy cells possess: the mitochondrial enzyme rhodanese. Benzaldehyde is a natural analgesic (pain reliever) & a natural anti-inflammatory (anti-swelling) agent. So from grass & clover (& other wild greens shoots & seeds) domestic cats & dogs acquire vitamin B17 that anesthetizes pain, reduces swelling & kills cancer cells. The bitterness of the grass is the taste of cyanide. Cyanide doesn't alleviate nausea. No human eats leaf spinach or collard greens to relieve an upset stomach, nor to initiate vomiting.