Garlic, in all its bad breath-inducing, but oh-so-flavorful glory, has been long-revered for its natural bacteria-fighting capabilities. In fact, it was even dubbed "Russian penicillin" during World War II because physicians fell back on garlic to treat illness when they ran out of prescription antibiotics [source: NYU Langone Medical Center].
Garlic also possesses an impressive ability to know when to say "when." Research has shown that the herb is adept at managing the level of Heliobacter pylori bacterium in the digestive tract, without completely eliminating it. Too much H. pylori can result in stomach ulcers, with too little causing other strain to the gut. Stomach cancer is one of the top two cancers worldwide, and the researchers found that populations that ate a lot of Allium vegetables (like onions, scallions but particularly garlic) had a lower incidence of stomach cancers [source: Sivam et al.]. Although the topic is still being studied, there is evidence that fresh garlic packs enough punch to kill nasty bugs like MRSA, Escherichia coli and Salmonella enteritidis [source: MedlinePlus].