Fructans, a complex carbohydrate found in onions, help those “good” bacteria in your gut grow. This may help keep the stomach bug at bay while at the same time preventing carcinogens from being activated in the colon.
A 2001 British study involving 146 healthy adults revealed that people who were given a garlic supplement were less likely to get sick — and more likely to recover faster if they did get sick — than those who were given placebos. Scientists say this is because garlic contains the active compound allicin. They also say more research is needed to confirm the exact role garlic plays in fending off disease. However, all eggheads agree on one thing: Raw garlic will make your breath reek. So maybe opt for pills instead.