Pre-formed vitamin A can be toxic at high levels (>10,000 IU or 3,000 mcg), thus, unless instructed by a qualified doctor, you would never take a daily supplement or combination of supplements containing anything near this amount. But the point is, this level could be achieved using supplements since the supplement(s) would contain pure pre-formed vitamin A. On the other hand, unless you were eating a very unusual high animal protein diet regularly containing red/organ meats, you would never reach a toxic level of vitamin A from foods. Hypervitaminosis A refers to high storage levels of vitamin A in the body that can lead to toxic symptoms. There are four major adverse effects of hypervitaminosis A: birth defects, liver abnormalities, reduced bone mineral density that may result in osteoporosis and central nervous system disorders. The RDA for vitamin A is 2310 IU and 3000 IU for females and males respectively and it’s important you average this amount daily because vitamin A plays roles in bone growth, immune function, reproduction, vision, cell division important to all parts of the body, etc. Your daily multivitamin and mineral formula (MVM) generally contains 1-2000IUs of pre-formed vitamin A leaving plenty of room for food vitamin A. The remainder of your body’s vitamin A needs will be supplied by a pro-vitamin A source such as beta-carotene from your MVM and fruits and vegetables from your diet. Pro-vitamin A will not be converted to vitamin A unless you body needs it, thus no matter how much pro-vitamin A you consume, you will not reach a toxic level of A. Therefore, the combination of a good MVM and a healthy diet assures no toxicity while delivering the right amount of overall vitamin A.