It's okay to take vitamins if you don't eat right. Take care not to overdose on Vitamin A, D, E, K, Calcium, and Iron. You should always run a CMP, vitamin profile, and iron before you start one. The chances of it being stored in the body and causing liver damage are high. Vitamins and supplements help regulate hormones and enzyme reactions. For example low vitamin D have symptoms almost similar to thyroid issues. A low vitamin D level weakens your bones, makes you tired, causes libido problems, hair loss and depression