Colds and flu viruses have a way of creeping up on you. One day, you’re feeling great, and the next—well, not so much. There are all sorts of “treatments” out there to make the virus more manageable and you, more comfortable. But what if there was a way to prevent the viruses and bacteria in the first place, and you had to look no further than your kitchen?

Traditional Chinese medicine teaches that certain foods have medicinal properties. Whether taken orally, used topically, or in this case, simply sliced, foods are amazing resources. Understanding the properties of these foods can be very beneficial in your path toward healing.

Using onions to absorb viruses and bacteria dates back to the early 1900s when white onions were used to ward off the plague. Once an onion is cut, the onion begins to absorb bacteria. (Hence the reason cut onions should not be left out or stored for a later date. A better method is to chop a leftover onion and freeze it in a small bag or container.) Although it’s a drag for cooking, the fact that onions can purify the air means that they can be helpful in other areas, too. The next time someone is your house is sick, place a cut onion next to their bed and give it a whirl.

What’s the science behind this? Onions, garlic, shallots and leeks are rich in sulfur—giving them their classic smell—while helping to detox the body. In lieu of sleeping next to a cut onion, try placing a cut onion in the exact center of the bottom of each foot before bedtime. Place a bandage over the onion to keep it in place, or simply wear a sock over the onion. This point on the foot is called “Yongquan” or Kidney 1, which stimulates a key point on the Kidney channel. The idea is for the onion to pull the impurities from the body.