Adequately feeding your immune system boosts its fighting power. Immune boosters work in many ways. They increase the number of white cells in the immune system army, train them to fight better, and help them form an overall better battle plan. Boosters also help to eliminate the deadwood in the army, substances that drag the body down. Here are the top eight nutrients to add to your family's diet to cut down on days missed from work and school because of illness.