If you're feeling weak, tired and depressed, it would be wise to take a look at your diet. When you're not receiving an adequate supply of the essential nutrients your body needs, that dietary shortfall can influence the balance of chemicals that keep your nervous system active and efficient. Vitamin B-12 is a vitamin that is especially crucial to the functioning of your nervous system, which includes your brain and its ability to perform cognitive functions.
Dietary B12
Most people in the United States receive enough B-12 through the foods they eat. B-12 rich food sources, such as red meat, poultry, fish, eggs, milk and other dairy products, are plentiful in the typical American diet. In fact, as the Office of Dietary Supplements explains, it's so plentiful that in most cases B-12 deficiencies are not caused by a lack of B-12 in the foods you eat, but rather by an inability of your gastrointestinal system to properly absorb B-12 due to some underlying disorder. One group that can experience a dietary lack of B-12 is strict vegans. The lack of B-12 in plant-based diets can cause B-12 deficiencies in vegans unless they eat foods that are fortified with the nutrient, or take a B-12 supplement.
Gastrointestinal Absorption
Your body needs hydrochloric acid to detach B-12 from the protein based foods that supply it. Elderly people sometimes experience a decrease in their body's ability to produce hydrochloric acid, thus B-12 deficiencies are more common in elderly populations. Pernicious anemia can also cause B-12 deficiency, as those with this disorder lack intrinsic factor, an enzyme that enables the intestines to absorb B-12. Celiac disease, Crohn's disease, chronic alcoholism and a history of prior gastrointestinal surgery can also decrease your ability to absorb B-12.
Deficiency and Mental Function
Vitamin B-12 is necessary for your nervous system to function properly. Your nervous system consists of your brain, spinal cord and the nerves that serve your entire body. When B-12 deficiency occurs, the outer layer of your nerves, called the myelin sheath, can be damaged according to the Linus Pauling Institute. When the nerves in your brain are not functioning properly due to B-12 deficiency, cognitive symptoms and mood disorders can result. These can include depression, dementia, confusion and memory loss.
Treatment
If you're concerned about possible B-12 deficiency, consult your doctor. She can assess your B-12 levels, and administer B-12 injections if necessary. If you have pernicious anemia, B-12 supplementation will be required for the rest of your life, but that's far better than a lifetime of depression. The recommended daily allowance of B-12 for most adults is 2.4 mcg, but you may require more depending on your doctor's recommendation.
