Cold and flu season is still upon us, and we all want to do everything we can to avoid getting sick. Washing our hands and logging enough sleep are a good start. But when it comes to protecting your immune system, diet counts too. So if you want to lower your chances of turning into a coughing, sniffing mess this month, consider adding some of these immune-boosting superfoods to your diet. Blueberries contain a compound (pterostilbene) which helps the body's first line of defense to combat bacterial infection. They also contain favonoids, which are broken down by a certain type of gut microbe, producing metabolites that may help prevent the flu. Turmeric has been used for centuries to treat infections. A chemical found in turmeric, works its way into cell membranes, improving their ability to ward off infectious microbes. Garlic is a disease-fighting powerhouse. It plays a role in how the body produces antibodies to fight off bad-for-you bugs. Even if you do get sick, aged garlic extract can shorten your cold duration by 61%, according to a study in the Clinical Nutrition Journal. Spinach is packed with antioxidants and nutrients like vitamin E and vitamin C that may be able to help the immune system beat infections. Sweet potatoes have an insane amount of vitamin C, and are packed with vitamin A to boot. Both can help protect and strengthen your immune system so you can more efficiently fight off sickness. Oysters are rich in zinc, a mineral that helps your white blood cells reproduce at a quicker rate. That boost may let you fight off harmful bugs more easily.