Question: what vitamins are essential for immune system?
Answer: Vitamin C. You probably know about vitamin C's connection to the immune system, but did you know you can get it from much more than just citrus fruits? ... 
Vitamin E. Like vitamin C, vitamin E can be a powerful antioxidant that helps your body fight off infection. ... 
Vitamin A. ... 
Vitamin D. ... 
Folate/folic acid. ... 
Iron. ... 
Selenium. ... 
Zinc.