There could be several reasons for this. Many people fail to get the right amount of nutrients every day. In addition, our soil is depleted and our food no longer contains the amount of vitamins and minerals that it used to. In certain circumstances, such as pregnancy, sports, aging or chronic illness, your body needs extra nutrients. In addition, people choose a supplement for its specific effect, such as for a good night's sleep, to support strong bones or as a natural sedative in stressful situations.