## Body overview The balance of vitamins and minerals is important for all body systems. For example, vitamin A deficiency can lead to eye disease and loss of vision, B6, B9, and B12 deficiency can lead to anemia, D deficiency can lead to rickets in children and osteoporosis in adults, and E deficiency can lead to problems with the skin, intestines, and nervous system. The principle "the more, the better" doesn't apply here, because an overabundance of certain vitamins and minerals can also cause serious complications. This is why doctors insist on tests and do not recommend buying multivitamins. First, without tests, you'll never know exactly what vitamins and minerals you should take and those you do not need to take. Second, while multivitamins contain many different substances their small dosages mean you may not be getting enough of certain vitamins. ## Warning signs Deficiencies of various vitamins and minerals have many specific symptoms, but some occur most often and should lead you to think about the problem. These include: - Constant fatigue - Depressed mood - Trouble sleeping - Frequent colds - Cramps in the calf muscles - Hair and nail problems - Digestive problems - Cellulite - Dizziness - Bleeding gums and tendency to get skin bruises - Joint pain By choosing the right vitamin complex, you can prevent or even “fix” issues like these. At the initial stage, vitamin imbalances may not manifest themselves in any way. ## What to take first Of course, the decisive word here is your doctor, who will prescribe tests based on your medical history and well-being. Typically the absolute minimum includes [B12](https://ul.orna.me/KOge/librarybiomarker?id=112), B9, and [D](https://ul.orna.me/KOge/librarybiomarker?id=187) vitamins. If tests show you're deficient in a certain area, your doctor will choose supplements and dosages for each. There is no sense in self-treatment, and sometimes it is even dangerous, because, for some conditions, some vitamins and supplements may not be suitable for you. You can find out the optimal values of certain indicators in our appendix.