 However, don't just eat raw salads because many vegetables release more health-boosting nutrients and antioxidants when they're cooked. So, for example, if mushrooms, carrots, spinach, or peppers are on the menu, boil or steam them until they're slightly firm but mashable, and then add your favorite protein to the meals, but skip processed and packaged foods. So grilled chicken instead of chicken nuggets, that's because processed foods tend to contain preservatives that kill the good bacteria in your gut and will weaken your body's immune response.