To best protect your body from harm, every component of your immune system needs to perform exactly according to plan. The best way you can ensure that happens is to practice the good-for-you behaviors every day that your immune system runs on. When it comes to a diet that supports good immune health, focus on incorporating more plants and plant-based foods. Add fruits and veggies to soups and stews, smoothies, and salads, or eat them as snacks, Lin says. Carrots, broccoli, spinach, red bell peppers, apricots, citrus fruits.