Symptoms of a not getting enough vitamin B-12 develop slowly, but they include fatigue, weakness, heart palpitations, shortness of breath and a sore tongue. A doctor can confirm the patient's B-12 deficiency using the results from blood tests and, if necessary, a bone marrow biopsy, according to Drugs.com. Treatment includes replacing the missing vitamin through dietary changes, supplements or injections.
Most people get enough vitamin B-12 from their diet. The vitamin comes from animal sources, so vegans who do not consume enough eggs or dairy products are more likely to develop a deficiency, warns Drugs.com. Since the body stores enough of the vitamin to last for several years, most people develop problems due to nondietary reasons.
Patients who lack the intrinsic factor that binds to the vitamin in the stomach develop a deficiency because the stomach destroys it before its absorption into the intestine. Those who have had a portion of the stomach surgically removed also develop problems with absorption. Health conditions such as diabetes cause an overgrowth of bacteria, which absorb the B-12 before the digestive system can causing a deficiency, reports Drugs.com.
A long-term vitamin B-12 deficiency leads to irreversible damage to the nerve cells. Patients with this type of damage may experience depression, memory loss, difficulty walking and psychosis, according to Drugs.com.