The body needs vitamin B-12, a water-soluble vitamin, to produce healthy red blood cells. Vitamin B-12 also plays an important role in DNA synthesis, fat and protein metabolism and neurological function. Insufficient intake or absorption of vitamin B-12 can cause vitamin B-12 deficiency anemia, or a low count of red blood cells. In many cases, B-12 deficiency anemia may cause mild or unnoticeable symptoms. In some cases, however, B-12 deficiency may cause severe nervous system or neurological damage.
Low Energy
Megaloblastic anemia caused by vitamin B-12 deficiency can cause a general lack of energy, with symptoms such as fatigue, weakness and shortness of breath, especially when exercising. People with vitamin B-12 deficiency anemia may also experience light-headedness upon standing up.
Digestive Symptoms
Vitamin B-12 deficiency anemia can cause digestive problems, with symptoms such as diarrhea, constipation and loss of appetite. These symptoms may lead to unintended weight loss.
Other Symptoms
Other common symptoms of vitamin B-12 deficiency anemia include pale skin and glossitis, or a sore or inflamed tongue. Vitamin B-12 deficiency during infancy may cause movement disorders, developmental delays and failure to thrive.
Nerve Damage
Prolonged, untreated vitamin B-12 deficiency can cause irreversible damage to the peripheral nervous system, causing peripheral neuropathy, or numbness and tingling in the hands and feet. Nerve damage caused by B-12 deficiency can also cause neurological changes, leading to confusion, depression, memory loss and, in severe cases, dementia. In some cases, neurological symptoms of vitamin B-12 deficiency occur without any common symptoms of anemia, notes the National Institutes of Health Office of Dietary Supplements. For example, a high intake of folic acid can correct the anemia associated with B-12 deficiency, making the deficiency harder to detect.
Causes and Treatment
Vegetarians and vegans who do not eat animal products may not get enough vitamin B-12 without taking supplements or eating fortified foods. Individuals with underlying conditions that hinder vitamin B-12 absorption also have a higher risk of deficiency. Atrophic gastritis, celiac disease, Crohn's disease, gastrointestinal surgery and pernicious anemia can all hinder B-12 absorption. Doctors often treat vitamin B-12 deficiency with intramuscular B-12 shots to bypass absorption problems. High oral doses of the vitamin may also treat deficiencies effectively, notes the National Institutes of Health Office of Dietary Supplements.
