A main benefit of 400 international units (IUs) of vitamin E can be for vitamin E deficiencies caused by certain disorders or digestive problems. However, vitamin E also has many functions in the body, such as helping in the production of red blood cells and assisting the body maintain its store of vitamin K, as noted by the University of Maryland Medical Center.
Additionally, vitamin E is a fat-soluble antioxidant that can be beneficial for skin health, the eyes and the immune system. In particular, a study indicated that 400 IUs of vitamin E, which was combined with 80 milligrams of zinc, 15 milligrams of beta-carotene and 500 milligrams of vitamin C, may protect the eyes against macular degeneration, notes the University of Maryland Medical Center.
Although rare, a vitamin E deficiency can develop in people with either a fat malabsorption problem or conditions that include pancreatititis and cystic fibrosis. For a vitamin E deficiency caused by fat malabsorption, a treatment option is to use a supplement of 200 to 400 IUs of mixed tocophero (family of vitamin E compounds), notes Merck Manual.