Tonia Reinhard, senior lecturer in nutrition and food science at Wayne State University, offers tips on immune-boosting, nutrient-dense "superfoods" that will help improve your body's ability to fight off disease, particularly during the current cold and flu season. "Nutrient-density refers to the amount of essential nutrients or health-promoting phytochemicals provided per calorie," says Reinhard. She recommends five superfoods during cold and flu season: Salmon, Greek yogurt, eggs, nuts, bell peppers and dark leafy greens. While Reinhard says vitamin C can't make a cold or flu go away, it can reduce the time you're affected by it.

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