Foods that contain below elements will help boosting immune system:
Vitamin A, B, C, E
Vitamin A prevents bacteria and viruses invading our bodies, it can be taken from orange/red plants, such as pumpkin, carrot, tomatoes etc.
Vitamin B can promote metabolism and produce antibodies. It is contained in whole grain carbohydrates, including oats, whole wheat bread, red rice / brown rice, etc.
Vitamin C boosts the activity of immune cells, boosts immunity, and antioxidants help remove free radicals that age the body.
Vitamin E is a powerful antioxidant that helps the body fight off infection. Foods rich in vitamin E include nuts, seeds and spinach.
Omega 3 fatty acids
It has anti-inflammatory and can reduce cell inflammation. It is in eggs, salmon, walnuts.
Protein
It is composed of different amino acids, which help the body to make antibodies, enzymes, etc. You can found it in meat, beans, eggs, milk, etc.