As we age, our memory and mental functions deteriorate. While a sudden decline in cognitive function should be examined by a physician, a gradual decline is normal. Deficiencies in vitamins contribute to decreased mental function. Dietary and vitamin supplements may also improve memory and thinking, and subsequently delay the onset of age-related mental decline.

Dietary supplements that have been proven to be useful in increasing mental functions, and delaying mental decline or progression in Alzheimer's are acetyl L-carnitine and phosphatidylserine. All have roles in the production of neurotransmitters, which deliver information from neurons to other cells. The herb ginkgo is also known to improve cognitive abilities.In addition, antioxidants such as vitamin E, which stabilizes cell-damaging free radicals, can improve brain function and may actually decrease the risk of developing Alzheimer's.

Vitamin B deficiencies, particularly vitamins B12 and B6, can contribute to poor mental performance; a deficiency in vitamin B1, which plays a part in transmitting information in the brain, is commonly seen in individuals who suffer from Alzheimer's. Low levels of the mineral zinc can also decrease memory and alertness. These can be addressed by taking a regular dose of vitamin B complex and zinc daily.