Vitamin & mineral supplements should never replace a well balanced, healthy diet.
Most dietitians advocate a “food first” approach. Individual dietary requirements for both macro & micro nutrients can (in most cases) be achieved by consuming a well balanced & varied diet, mostly consisting of unprocessed foods.
Research indicates that vitamins & minerals from the food you eat are better absorbed & utilised by the body, compared to those contained in a pill.
Food is a complex source of a variety of nutrients, all working in harmony together, which is why whole foods are always better nutritionally than those nutrients taken in isolation (as a supplement).
Obviously, there will be certain conditions where taking a vitamin & mineral supplement may be required (for example, during pregnancy or breastfeeding, medical conditions causing malabsorption, some vegans or vegetarians or other medical conditions with a diagnosed nutritional deficiency).
Always consult with a GP or accredited practising dietitian (APD) under these circumstances for guidance.
For the most part, companies are making a lot of money out of consumers taking supplements unnecessarily !!