The vitamin B - 12 , or what is known Eopalaman , a soluble vitamins in the water, which is essential for the formation of red blood cells, and also the cell, and enters the nerve function, and the production of nuclear chromosome DNA , and is this vitamin Of the vitamins that the body can store over several years,  It is one of the nutrients that the body cannot produce on its own, so it must be obtained from the diet or nutritional supplements,  and cobalamin is derived exclusively from bacterial sources, which is An essential cofactor of three known enzyme reactions. 
To learn more about this vitamin, you can refer to the article on the benefits of vitamin B12 .
Symptoms of vitamin B12 deficiency
Vitamin B12 deficiency develops slowly, which leads to symptoms gradually appearing, and they worsen over time, and may also appear relatively quickly, and the group of symptoms that this vitamin deficiency can cause may be mixed with symptoms of some other conditions,  and include symptoms of vitamin deficiency B12 What follows: 
- Jaundice or paleness of the skin: Often people with vitamin B12 deficiency appear pale, or have a slight yellow color on the skin, and in the whites of the eyes, and this condition is known as jaundice , which occurs as a result of problems in the production of red blood cells in the body Due to a lack of vitamin B12, due to its role in the production of the chromosomal DNA necessary for the manufacture of red blood cells, and when it is deficient, the basis for building cells is incomplete, and they become unable to divide. Vitamin B12 deficiency causes a type of anemia , known as megaloblastic anemia, as the red blood cells produced in the bone marrow are large and fragile, making them too large to be transmitted from the bone marrow and into the circulatory system. Consequently, the number of red blood cells becomes insufficient in the circulatory system, which causes pallor of the skin.
- Asthenia and fatigue: Fatigue and weakness are common symptoms of vitamin B12 deficiency, and they occur as a result of the body not containing enough vitamin B12 to make red blood cells, which transport oxygen throughout the body, so the body cannot efficiently transfer oxygen to its cells, which It causes these symptoms, and the elderly develop a type of anemia, known as pernicious anemia, which is often caused by autoimmune diseases, and people with pernicious anemia are unable to produce enough protein Which is known as the intrinsic factor, which is necessary to prevent vitamin B12 deficiency, as it binds to this vitamin in the intestine so that the body can absorb it.
- Changes in movement: If not treated, vitamin B12 deficiency causes damage to the nervous system , which can cause changes in the way of walking or movement, and these changes may affect balance and coordination, which increases the risk of falling, and these symptoms often appear in Elderly people in the case of undiagnosed vitamin B12 deficiency, as they are more susceptible to deficiency of this vitamin, and therefore reducing the incidence of this deficiency or treating it may improve their mobility. In addition, these symptoms may occur in young people who suffer from Acute, untreated deficiency.
- Shortness of breath and dizziness: People with anemia due to a lack of vitamin B12 may feel shortness of breath and dizziness, especially when exerting an effort, as the body lacks red blood cells necessary to obtain an adequate amount of oxygen for cells, but these symptoms may be for several reasons, Therefore, you should see a doctor if you are breathing abnormally.
- Vision disturbance: Blurred and blurred vision is a symptom of vitamin B12 deficiency, which can occur as a result of untreated vitamin B12 deficiency, which leads to damage to the nervous system of the optic nerve of the eyes, and this damage can lead to disruption of the nerve signals that travel from the eyes to The brain, which impairs vision, and this condition is known as optic neuropathy.
- Tingling sensation: One of the most serious side effects of long-term vitamin B12 deficiency is nerve damage, and this symptom can occur over time. Vitamin B12 is an important contributor to the metabolic pathway that produces the fatty substance myelin , a substance that surrounds nerves, as a form of protection and insulation, and when vitamin B12 is absent, myelin is produced in a different way, and the nervous system becomes unable to perform its function. correctly.
- One of the signs of this symptom is a disorder, or the sensation of touching pins and needles, which resembles a tingling sensation in the hands and feet. It is worth noting that the neurological symptoms associated with vitamin B12 deficiency usually occur alongside anemia, however, a study published in the journal The The New England Journal of Medicine, conducted on a group of people suffering from neurological and psychological disorders, that these disorders caused by vitamin B12 deficiency most commonly occur in the absence of anemia, as approximately 28% of the participants suffer from neurological symptoms as a result of vitamin B12 deficiency, Without anemia,  it should be noted that tingling is a common symptom that has many causes, so the occurrence of this symptom alone is not an indication of the occurrence of vitamin B12 deficiency in most cases. 
- Glossitis and mouth ulcers: The symptoms of glossitis are a change in the shape of the tongue, and its color, which leads to its swelling, redness, and pain, and a study published in the Journal of the American Academy of Dermatology in 2009 showed that a swollen tongue, or Inflamed and with long, straight lesions can be an early sign of a vitamin B-12 deficiency.  This inflammation can affect the way we speak and eat. In addition, it is possible for people who are deficient in vitamin B12 to suffer from a number of other symptoms, such as: mouth ulcers, a feeling of tingling in the tongue, and a feeling of itching and burning in the mouth. . 
- Mood changes: People with a vitamin B12 deficiency often suffer from mood changes, and low levels of this vitamin in the body are linked to mood and brain disorders, such as: depression, dementiaLow levels of vitamin B12 increases the level of homocysteine, which causes damage to brain tissue, in addition to that it interferes with the signals sent from the brain, causing a change in mood, and it is worth noting that these symptoms can occur for several reasons, so the effect of Vitamin B12 supplements to alleviate these symptoms are still unclear.On the other hand, it was found in a systematic review consisting of a group of studies and published in International Psychogeriatrics in 2015 that the use of vitamin B12 does not reduce the severity of depressive symptoms over a period of time. A short period of time, but it may be useful in the long term to control these symptoms for some individuals, but more studies are needed to prove this relationship. 
- Other symptoms: We mention the following: 
- Diarrhea or constipation.
- Loss of appetite .
- Feeling irritable.
- Confusion, or change in mental state, such as dementia in severe cases.
- Trouble concentrating.
- Psychosis, which is a loss of contact with reality.
Causes of vitamin B12 deficiency
Vitamin B12 deficiency occurs due to a number of reasons, including the following: 
- Not eating enough vitamin B12: It is possible that vegetarians are more susceptible to vitamin B12 deficiency, and infants of vegetarian mothers may develop a deficiency of vitamin B12 by the age of 4 to 6 months, as most of them have limited stores of vitamin B12 in the liver, and it leads to the growth rate Children rapidly to high need for nutrients.
- Inadequate absorption of vitamin B12: Inadequate absorption of vitamin B12 is one of the most common causes of vitamin B12 deficiency, and the decrease in gastric acid secretion leads to a decrease in the ability to absorb vitamin B12 in the elderly, and in such cases it is recommended to take crystallized vitamin B12, as found in Vitamin supplements, which the body of those suffering from this condition can absorb, as for vitamin B12, which is found in food sources, it is difficult for their body to absorb it naturally, and insufficient absorption may occur in people with a condition called Blind loop syndrome, with Bacterial overgrowth or tapeworm infectionAs a result of eating raw fish, and in these cases bacteria or parasites use digested vitamin B12, which reduces the amounts available for absorption, and the body may not be able to absorb sufficient amounts of vitamin B12 in the event of damage to the sites of absorption in a part of the intestine called the ileum : Ileum), caused by inflammatory bowel disease or by having it surgically removed.
- Less common causes of insufficient absorption of vitamin B12 include a number of health conditions, such as: chronic pancreatitis , stomach surgery, or bariatric surgery, malabsorption syndromes, AIDS , and a genetic disorder that causes malabsorption in the last part of the small intestine, which is known as Imerslund. Graesbeck syndrome.
- Use of certain medications: Taking certain medications such as antacids, metformin, and frequent exposure to nitrous oxide may increase the risk of developing vitamin B12 deficiency.
- Decreased use of vitamin B12 in the body: This is one of the least common causes.
Treating vitamin B12 deficiency
People who suffer from pernicious anemia or problems absorbing vitamin B12 may need to take vitamin B12 injections, and they must continue to take them, and then take high doses of his dietary supplement orally, under the supervision of a doctor, as for people who do not take Animal products, they can change their diet to include cereals fortified with vitamin B12, or take nutritional supplements, or through injection, and a high dose of this vitamin can be taken orally in cases of deficiency, while the elderly who suffer from a deficiency of this vitamin, it is preferred To take vitamin B-12 supplements daily, or take multivitamin supplements that contain vitamin B12, which may help solve the problem, but it should be noted that nerve damage caused by deficiency can be permanent. 
The recommended amount of vitamin B12
The following table shows the daily recommended amounts of vitamin B12 for different age groups: 
|Age group||Daily amount recommended (micrograms)|
|Infants from birth to 6 months||0.4|
|Infants 7 to 12 months||0.5|
|Children 1 to 3 years old||0.9|
|Children 4 to 8 years old||1.2|
|From 9 to 13 years old||1.8|
|From the age of 14 years and over||2.4|
- "Vitamin B-12" , www.mayoclinic.org , 17-10-2017, Retrieved 5-1-2020. Edited.
- Arlene Semeco (3-5-2018), "Top 12 Foods That Are High in Vitamin B12" , www.healthline.com , Retrieved 5-1-2020. Edited.
- H. Markle, D. Greenway (9-27-2008), “Cobalamin” , Critical Reviews in Clinical Laboratory Sciences , Issue 4, Folder 33, Page 247-356. Edited.
- Patrick Skerrett (10-1-2013), “Vitamin B12 deficiency can be sneaky, harmful , ” www.health.harvard.edu , Retrieved 5-1-2019. Edited.
- Helen is the West (7-10-2017), "9 Signs And the Symptoms Of the Vitamin B12 is Deficiency" , Www.healthline.com , Retrieved 5-1-2019. Edited.
- John Lindenbaum, Edward Healton, David Savage And Others (6-30-1988), “Neuropsychiatric Disorders Caused by Cobalamin Deficiency in the Absence of Anemia or Macrocytosis” , The New England Journal Of Medicine , Issue 26, Folder 318, Page 1720 -1728. Edited.
- Jordi Graells, Rosa Ojeda, Cristina Muniesa, And Others (5-2009), "Glossitis with linear lesions: An early sign of vitamin B12 deficiency" , Journal of the American Academy of Dermatology , Issue 3, Folder 60, Page 498- 500. Edited.
- Osvaldo Almeida, Andrew Ford, Leon Flicker (3-2-2015), “Systematic review and meta-analysis of randomized placebo-controlled trials of folate and vitamin B12 for depression” , Cambridge university press , Issue 5, Folder 27, Page 727-737. Edited.
- "Vitamin B12 deficiency anemia" , www.medlineplus.gov , Retrieved 5-1-2020. Edited.
- Larry Johnson (8-2019), "Vitamin B12 Deficiency" , www.msdmanuals.com , Retrieved 5-1-2020. Edited.
- "Vitamin B12: What to Know" , www.webmd.com , Retrieved 5-1-2020. Edited.
- "Vitamin B12" , www.ods.od.nih.gov , Retrieved 5-1-2020. Edited.