<unk> , also known as hypovitaminosis<unk> , or cobalamin<unk> , is the medical condition in which the blood and tissue have a lower than normal level of<unk> <unk> . Symptoms may develop slowly and worsen over time. In mild<unk> , a person may feel tired and have anemia, a reduced number of red blood cells. In moderate<unk> , soreness of the tongue, mouth ulcers, breathlessness, feeling faint, rapid heartbeat, low blood pressure, pallor, hair loss and severe joint pain and the beginning of neurological symptoms, including abnormal sensations such as pins and needles, numbness and tinnitus may occur. Severe<unk>  may include symptoms of reduced heart function as well as more severe neurological symptoms, including changes in reflexes, poor muscle function, memory problems, blurred vision, irritability, ataxia, decreased taste, decreased level of consciousness, depression, anxiety, guilt and psychosis. If left untreated, some of these changes can become irreversible. Temporary infertility reversible with treatment, may occur. In infants of vegans, undetected and untreated<unk>  can lead to poor growth, poor development, and difficulties with movement. Causes are usually related to conditions that give rise to malabsorption of<unk> <unk>  particularly autoimmune gastritis in pernicious anemia. Other conditions giving rise to malabsorption include surgical removal of the stomach, chronic inflammation of the pancreas, intestinal parasites, certain medications such as long-term use of proton pump inhibitors, H2-receptor blockers, and metformin, and some genetic disorders.<unk>  can also be caused by inadequate dietary intake such as with the diets of vegetarians, and vegans, and in the malnourished.<unk>  may be caused by increased needs of the body for example in those with HIV/AIDS, and shortened red blood cell lifespan. Diagnosis is typically based on blood levels of<unk> <unk>  below 150–180 pmol/L (200 to 250 pg/mL) in adults. Elevated methylmalonic acid levels may also indicate a<unk> . A type of anemia known as megaloblastic anemia is often but not always present. Individuals with low or marginal values of<unk> <unk>  in the range of 148–221 pmol/L (200–300 pg/mL) may not have classic neurological or hematological signs or symptoms. Treatment consists of oral or injected<unk> <unk>  supplementation; initially in high daily doses, followed by less frequent lower doses as the condition improves. If a reversible cause is found, that cause should be corrected if possible. If no reversible cause is found, or when found it cannot be eliminated, lifelong<unk> <unk>  administration is usually recommended. A nasal spray is also available.<unk>  is preventable with supplements and this is recommended in pregnant vegetarians and vegans, and not harmful in others. Risk of toxicity due to<unk> <unk>  is low.<unk>  in the US and the UK is estimated to occur in about 6 percent of those under the age of 60, and 20 percent of those over the age of 60. In Latin America, about 40 percent are estimated to be affected, and this may be as high as 80 percent in parts of Africa and Asia. Marginal<unk>  is much more common and may occur in up to 40% of Western populations.
Vitamin B12 deficiency
Vitamin A deficiency
Copper deficiency
Biotin deficiency
Megavitamin-B6 syndrome
Vitamin E deficiency
Fluorine deficiency
Zinc deficiency