The most successful ways to help your immune system is through prevention and protection— in other words, practicing tactics like washing your hands properly, avoiding spoiled food, and staying up-to-date on your vaccines. Aside from vaccinations, none of these strategies actually affects your immune system. Instead, they help you fend off pathogens before they get inside.
Although there’s no clear-cut way to beef up your body’s defenses, some simple practices may help.
• Eat a balanced diet. There’s no immune system-boosting super food, but a balanced diet is a good basis for fighting disease. Scientists link deficiencies in folic acid and in vitamins A, B, C, and E, to poor immune-system function.
• Avoid stress. And not just the mental kind. The physical wear and tear of weight loss diets and intense exercise also damps down your immune response. So do injuries, infections, heavy drinking, and pack-a-day smoking.
• Get a proper night’s sleep. It’s obvious, but worth repeating—studies find that 8 hours of nightly sleep boosts the level of immune cells in your body.
• Be optimistic. It sounds a bit foofy, but studies have consistently found that you can get someone’s body to produce more T cells if you force them to meditate, relax, watch funny TV, or hang out with friends.
Source of Information : Oreilly - Your Body Missing Manual