The human immune system can be weakened by poor diet, alcohol, smoking, processed foods, foods and drinks high in sugar and refined carbohydrate soda. Micronutrient deficiencies (eg vitamin A, B6, C, folic acid) may alter the immune responses. For immunity enhancement food is very important.
Citric fruits, almonds, green vegetables, ginger, garlic, seeds, turmeric are some immunity boosters. Another factor affecting the immune system is age. As we age, immune reabsorption capability becomes reduced.

Illnesses and disease take a toll on the Immune system as reactions can be underactive or overly active (as in asthma, allergic reactive), deficient (as in HIV), or against our own body autoimmune (as in rheumatoid arthritis).
SO WHAT CAN BE DONE?
Effective homeopathic treatment plans need to be made and followed for immunity enhancement for the body to achieve stability and well being. Healthy lifestyle boosts the immune system.