From Reactions:
Garlic is good for your body, great for your taste buds, but terrible for your breath. This episode looks at the plant beloved by chefs and feared by vampires. Once again we teamed up with the Compound Interest blog to break down the chemistry of garlic, and how to beat the bad breath it causes.
There are four main volatile organic compounds that contribute to garlic breath. None of them are actually present until garlic is crushed or chopped. These compounds also contain sulfur, which can penetrate bacteria cell membranes, making garlic an antibacterial assassin.