There are also a number of rare hereditary disorders which may respond to large doses of a particular vitamin or mineral. It is important that these individuals be under the care of a physician rather than being treated by self-medication. This notion is not true. Vitamins and minerals are potentially toxic when ingested in large amounts. When physiological mechanisms become saturated there is no improvement of any body function with additional intake of vitamins or minerals.
Vitamin D is the most toxic of the fat-soluble vitamins.
Persons who consume an ample supply of foods that are rich in beta-carotene have lower rates of cancer. However, some water-soluble vitamins are in fact toxic. Such amounts can produce toxic effects on the peripheral nervous system that may not be reversible. Many people consume large amounts of vitamin C on a regular basis in an attempt to protect themselves against the common cold, cancer, heart disease, and countless other disorders. Actually, it requires less than 100 mg daily to saturate body tissues.