You want an immune system that works like an offensive line on a football team, ready to tackle viruses, bacteria, and cancer. When you get a cold, break a bone, or suffer any other sickness or harm, your immune system recognizes that you’re unwell and dispatches a team of inflammatory cells to tackle what’s wrong.

Training your immune cells to attack is remarkably simple. The whole team of cells and proteins only need to learn what is “you” …