Doing a vitamin needs test takes about 20 minutes and you then find out which vitamins are most effective for you to eat to your body should be able to function optimally. When you have the correct nutritional status, the immune system handle what you are exposed to in everyday life.
There are lots of vitamins, minerals and other preparations on the market that may not suit you, others who are neither good nor bad and then there are those who are good and your body needs.
Do you eat vitamins you need in the right amount and as yours body can pick up and handle you will build yourself up and avoid adding energy and money on what doesn't work for you.