Even if you don't need prescription, these pills aren't harmless. It can creates unwanted effects like diarrhea, constipation, itching, urticaria and other symptoms. More than 48% of the canadian population believe that taking supplements is necessary for a good alimentation, but it is not. In fact, it doens't constitute a necessity if you are healthy.
Sometime, for divers reasons, a food or foods group is excluded or not eaten enough. Consequently, this can cause an insufficient intake of vitamins and minerals. Then, it's important to meet with an health professional like a nutritionist dietitian to get evaluated. After, this person will be able to determine necessity to take supplements and to know the best quantity to help your lack.
Therefore, there is two particular context where population groups are generally asked to get supplements. In fact, Health Canada ask to people of 50 and more to take each day vitamin D supplements (15 µg or 600 UI). And this, plus following recommendation of the new canadian food guideline.
In addition, all women which could be pregnant, pregnant women and ones breast-feeding should take each day a multivitamin which has 400 micrograms (0,4 m) of folic acid.
If not, it's better to take count foods as the best supplement. In fact, food, with great vitamins and minrals, contains phytochemicals compounds which favorise absorbtion and offers interesting benefits for health.