Vitamin A, beta-carotene, folic acid, vitamin B12, vitamin C, vitamin D, riboflavin, iron, zinc, and selenium may all have immunomodulating functions and could enhance the immune response rates of immunotherapy and even reduce irAEs. They play an important role in reducing oxidative stress in diseases and cancers.

Three pregnant women are sitting in a doctors. Three pregnant women are sitting in a doctors waiting room knitting. Mom 1 checks her watch and takes a pill "Vitamin C, good for mom, good for baby." Mom 2 takes a pill and says, "Vitamin A, good for mom, good for baby."
But the debate over whether all adults need to take vitamin D supplements is contentious. One study estimates that around 20% of the population in the UK has a profound vitamin D deficiency 
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