There has been clinical evidence that shows that multivitamins do not actually improve health because the body does not absorb those you are not deficient in. People end up excreting the vitamins they are not deficient in which can actually cause some harm to their liver and kidneys while their bodies process the excess. Remember that vitamins are not a natural product, most are processed in some form. A natural food source that contains the vitamin that you should have in your diet is a much better alternative then a pill form, if possible. One of the best ways to determine whether you are deficient in any vitamins is to ask for blood work to be done at the office of your primary care physician. Once you have determined your vitamin deficiencies, it is necessary to know the benefits of the vitamins you need and the easiest sources of said supplements.
Below is some basic information on omega-3 and vitamin C.
*if you are not vitamin deficient, excess vitamin supplementation has not been shown to have benefit
**Always consult your doctor before use of any dietary supplements or change in diet