Vitamin E Requirements in Parenteral Nutrition

Patients with parenteral nutrition depend on an adequate supply of micronutrients, in particular, antioxidant vitamins and cofactors such as selenium. In cases of oxidative stress (eg, chronic inflammation, sepsis, lung distress syndrome, and organ failure), there is a higher need for antioxidants. One of the most important antioxidant vitamins is vitamin E. For very low birth weight infants the plasma level is an indicator for adequate supply and for safety. Safe and effective blood levels are between 23 and 46 μmol/L, maintained with a dose of 2.8 IU/kg body weight (1–2 mg/day). For safety reasons a plasma level of 80 μmol/L should not be exceeded. For adults, 10 IU/day (9.1 mg/day) are recommended. Whether this dose is sufficient to ensure body stores and sufficient antioxidant activity is controversial. If parenteral lipid emulsions are supplied there is an additional need for vitamin E to protect the lipids (polyunsaturated fatty acids) from lipid peroxidation and to deliver additional vitamin E. Dietary guidelines for healthy adults recommend an intake of polyunsaturated fatty acids equal to 10% of total energy and an intake of α-tocopherol greater than 0.4 mg/g of polyunsaturated fatty acids. Randomized clinical trials are performed using special formulations of vitamin E solutions because vitamin E is available only in lipid emulsions to protect lipids, but not in an isolated solution for parenteral supply.