GARLIC
People have been using garlic to ward of disease for thousands of years. And, more and more research suggest, it’s more than just folk medicine. One prominent study (PDF) found that people who took garlic supplements got few cold symptoms, and, if they did get sick, they were ill for less time than the placebo group.
If you can handle it, try eating a clove of garlic every day. But it does not just have to be the hard way — adding some minced garlic, fresh or cooked, is beneficial.