Vitamins unlikely to revitalize the mind
There is little proof that taking supplements prevents cognitive decline or dementia.
As people age, they tend to suffer from vitamin deficiencies. The elderly are commonly deficient in vitamin B12, for example, because they produce less stomach acid than younger people, and therefore are not as able to metabolize this vitamin from food sources. Age-related changes also make older adults less efficient at producing vitamin D following sun exposure.
Certain vitamin deficiencies can impair brain functioning. Probably the best known example is vitamin B12 deficiency, which can mimic symptoms of Alzheimer's disease and other types of dementia by causing disorientation and confusion. People can prevent or treat a vitamin B12 deficiency by taking supplements or eating fortified foods — which do not require stomach acid for absorption.