Doctors sometimes prescribe vitamin E to treat Alzheimer’s disease. One large federally funded study showed that vitamin E slightly delayed loss of ability to carry out daily activities and placement in residential care.

Scientists think vitamin E may help because it is an antioxidant, a substance that may protect nerve cells from certain kinds of chemical wear and tear.

No one should use vitamin E to treat Alzheimer’s disease except under the supervision of a physician. The doses used in the federal study were relatively high, and vitamin E can negatively interact with other medications, including those prescribed to keep blood from clotting.