Vitamin B-12 helps maintain healthy nerve cells and red blood cells. A vitamin B-12 deficiency — most common in older adults and vegetarians — can cause various signs and symptoms, including memory loss. In such cases, vitamin B-12 supplements can help improve memory.
In the absence of a vitamin B-12 deficiency, there's no evidence that vitamin B-12 supplements enhance memory for people who have Alzheimer's disease. Still, vitamin B-12 remains an important part of a healthy diet.
Vitamin B-12 is found naturally in foods that come from animals, including fish, meat and poultry. Many breakfast cereals are fortified with vitamin B-12 as well. If you're concerned that you're not getting enough vitamin B-12 or other specific nutrients, consult your doctor — especially if you're an older adult or a vegetarian.