Tahini, a spread made from ground sesame seeds and olive oil, is loaded with magnesium and zinc, two nutrients known to boost immunity. Add tahini to hummus or yogurt with a squeeze of fresh lemon juice and diced garlic for a zesty dip. Or, for a special treat, spread it on nutty whole-grain bread and add a drizzle of honey. Tahini, which contains just 89 calories per tablespoon, is also a great source of healthy fatty acids, thiamin, phosphorus and copper.