Vitamin B12 Foods

Vitamin B12 Foods- This article is about Vitamin B12, sources and foods rich in Vitamin B12. Here I have given details about the list of foods that are commonly available in the community and are rich sources of Vitamin B12.


Vitamin B12 is a water-soluble vitamin known as cobalamin that belongs to the family of B vitamins and comes to a number of eight in vitamin b family. Our body cannot synthesize vitamin B12 so we must take it through our diet (Vitamin B12 Foods) because it plays an important role in the metabolism of every cell of our body. It is a nutrient that is important for its conversion of food into glucose which provides us with the energy needed for many biochemical reactions of our body. It plays an important role in red blood cell formation and DNA synthesis.

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Discovery of vitamin B 12:

Vitamin B12 was firstly discovered by George Richard Minot and William Parry Murphy in 1926. They examined that eating a large quantity of liver helps the patient to recover from pernicious anemia by repairing their disrupted red blood cells. Pernicious anemia is a deficiency disease of vitamin B12 that effects the formation of normal red blood cells of our body.

Types of vitamin B12:

Vitamin B12 has a complex chemical structure and contain cobalt (35%) in the center of its corrin ring. It is the largest and structurally complex vitamin present in four vitamer forms.

  • Cyanocobalamin
  • Hydroxocobalamin
  • Methylcobalamin
  • Adenosylcobalamin

It is the most stable form of vitamin B12 that is chemically synthesized in labs for pharmaceutical purposes because it does not occur naturally in our body. It is mainly used in supplementation form to treat pernicious anemia and many other deficiency diseases of vitamin B12. It is also present in vitamin B12 rich food and used as a dietary supplement. It plays an integral role in blood formation, cell metabolism, reproduction, and growth.


This form of vitamin B12 is mainly produced by the bacteria and also found in Vitamin B12 food sources. It is used as the dietary supplement as well as in the form of intramuscular injections to treat vitamin B12 deficiency. It is more easily converted to the active forms of vitamin B12 in our body. It helps our body in energy production and protein synthesis. It plays an important role in pharmacology as an antidote that is used in the treatment of cyanide poisoning.

Methylcobalamin: It is the most active form of vitamin B12 that occurs naturally in our body. It provides a number of health benefits in our body and easily utilized in the body without any further conversion. It provides protection to the nervous system and supplies essential methyl groups that are important for body detoxification and for the biochemical reaction that takes place in our body. Read here about Sources of Calcium.


It is the active form of vitamin B12 that present naturally in our body i-e mainly stored in the liver. It is the least stable form of vitamin b12 in our body and easily converted to Methylcobalamin in the time of need of the body. They also worked together to provide coenzymes in different parts of our body tissues. It basically plays an important in metabolisms i-e in energy production. Read here about Causes of Obesity.

Sources of Vitamin B12: Vitamin B12 Foods

Vitamin B12 is an essential nutrient for our body. It plays important role in the normal functioning of our body i-e red blood cells formation, healthy brain and nerve functioning, metabolism of every cell, and DNA synthesis. Vitamin B12 is mainly produced by some species of bacteria and archaea because these bacterial species acquire all the genes that are needed for vitamin B12 synthesis. These species of bacteria are present in the soil. Ruminant animals get their vitamin B12 by the symbiotic relationship with their gut bacteria.

Vitamin B12 Foods
Vitamin B12 Foods

This synthesized vitamin B12 are then transferred and stored in animal tissues that are considered to be the richest sources of vitamin B12 like milk and meat products. It is not found naturally in plant foods, fortified cereals are the best alternative source of vitamin B12 for vegetarians that increase the bioavailability of vitamin B12 in their body. The food products of vitamin B12 that are listed below not only increases vitamin B12 levels in the human body and also prevent them from deficiency diseases:

Below is the detailed list of foods that are rich in vitamin B12: Vitamin B12 Foods List

  • Poultry meat like chicken, turkey.
  • Organ meat like liver, kidney.
  • Beef and lamb
  • Eggs
  • Pork
  • Sardines
  • Wild-caught salmon
  • Atlantic mackerel
  • Oysters
  • Crabs
  • Clams
  • Trout
  • Mussels
  • Tuna
  • Shrimps
  • Herrings
  • Milk i-e skim milk, buttermilk, chocolate milk.
  • Cheese i-e cottage cheese, Swiss cheese, cheddar cheese, mozzarella cheese etc.
  • Milk alternative i-e soy beverage

Richest sources of vitaminB12 and their RDI: Vitamin B12 Foods

Here is the list of Vitamin B12 Foods: vitamin b12 benefits are so many that I will suggest all my readers to start using Vitamin B12 on the regular basis.  We all must focus on quality nutrition and most important on Vitamin B12 Foods.

SourcesServing sizeRDI in (%)
Organ meat i-e liver and kidney of lamb3.5 ounces (100g)1500%  in liver

1300%in kidney
Clams20 small clams or

3.5 ounce (100 g)
SardinesOne cup (150g)200%
BeefOne steak (186g)200%
Fortified cereals¾ cups (29 g)137%
Tuna3.5 ounce (100g)

Fortified nutritional yeastTwo tablespoons

Trout3.5 ounce (100g)


SalmonOne-half fillet (178g)

Milk and dairy productsOne cup (240ml)18%
Swiss cheeseOne ounce (30g)


Eggs especially egg-yolkTwo large eggs (100g)


Recommended dietary allowance (RDA) for vitamin B12: vitamin b12 dosage

Vitamin B12 is not produced by the human body so we must take it through our diet or through supplementations to prevent the complications of vitamin B12 deficiency. RDA values of vitamin B12 varies according to age groups. The RDA value for elderly and adults is 2.4 mg. low levels of vitamin b12 are seen more in elderly because of poor dietary habits and malabsorption that are caused due to pernicious anemia and atrophic gastritis. Low levels of vitamin B12 can cause fatigue, weakness, nerve damage, intestinal problems, mood disturbance and even memory loss. The RDA values according to age groups and vitamin b12 dosage are listed below:

AGE GROUPSvitamin b12 dosage (RDA)
Birth to 6 months0.4 mcg
Infants 7 to 12 months0.5 mcg
Children 1-3 years

0.9 mcg

Children 4-8 years1.2 mcg
Children 9-13 years1.8 mcg

Teens 14-18 years

 2.4 mcg

Adults 2.4 mcg
Pregnant women2.6 mcg
Lactating women2.8 mcg

Functions of Vitamin B12- Vitamin B12 Benefits

Vitamin B12 is an essential nutrient that performs many functions in the human body and helps to treat many diseases like fatigue, weakness, high cholesterol levels, anemia, Alzheimer disease.

Here I have listed all the important functions of Vitamin B12 (Vitamin B12 Benefits)

  • Role of vitamin B12 in DNA Methylation:

Folate and vitamin B12 are two coenzymes that play important role in DNA synthesis and provide structural stability to many parts of chromosomes like centromere. They are involved in the synthesis of methionine and S-Adenosyl methionine. They participate in the monocarbonic acid metabolic pathway in which they act as methyl donors. They play important role in DNA methylation, most importantly during the phase of embryogenesis and carcinogenesis. In the process of the methylation of DNA, methyl groups are incorporated in the DNA molecules that modify the activity of DNA but their sequences remain intact. This process of DNA methylation is catalyzed by methyltransferases that transfer methyl groups from S-adenosyl methionine to cytosine. Vitamin B12 with the help of other vitamins like folate, pyridoxal 5 phosphate play a role of coenzyme for methyltransferase that plays its role in remethylation of homocysteine to methionine.

Vitamin b12 is also involved in the conversion of methyl THF to tetrahydrofolate (THF). Vitamin B12 and methyl THF are basically responsible for the conversion of homocysteine to methionine.

Methionine plays important role in the methylation of many biological molecules like DNA.

Low intake of vitamin B12 through diet effect DNA synthesis and lead towards DNA damage. Low serum level of vitamin B12 results in many diseases like Alzheimer disease, Dementia, Cardiovascular diseases (CVD), breast cancer etc.

  • Role of Vitamin B12 in red blood cells formation:

RBCs are produced in bone marrow during the process of erythropoiesis that is under the control of hormone erythropoietin (EPO). During the low oxygen distribution in the body and increased level of androgen, kidney cells i-e juxtaglomerular cells also produced EPO. RBCs also needed iron, folate, and vitamin B12 in addition to EPO for its normal production. Erythropoiesis is a process in which red blood cells are produced, during this process, new erythrocytes replaced old, damaged, and phagocytosed erythrocytes. The body needs iron, folate, and vitamin B12 for the proliferation of erythroblasts during the process of differentiation. Deficiency of iron, vitamin B12, and folate causes the impairment of DNA synthesis due to inhibition of purine and thymidylate syntheses result in erythroblast apoptosis that leads the body towards the condition of anemia because of the impairment of the normal process of erythropoiesis.

  • Role of vitamin B12 in energy production and in the proper metabolism of the body that keeps our body energize:

Vitamin B12 is a vital nutrient that is needed by our body to perform many useful functions like red blood cells formation, healthy nerves system, and DNA synthesis. One of the main functions of vitamin B12 is the production of energy and in the proper metabolism of every cell of the body. It helps the body in the breakdown of proteins, carbohydrates, and fats that provide the body with the surplus amount of energy to perform its essential functions. The most common side effect of vitamin B12 deficiency is the lack of energy that leads towards many serious health problems. Read here about Foods Rich in Vitamin E.

Vitamin B12 helps the body in the formation of hemoglobin inside red blood cells that transport oxygen throughout the cells of our body including brain cells, skeletal cells, muscles cells etc. Without vitamin B12 hemoglobin production halts result in the low level of oxygen in the body that results in the condition of fatigue and in problems like pernicious anemia and megaloblastic anemia. Vitamin B12 regulates energy levels of the body by breaking all the food that we ingested into usable forms of energy. Read here about Sources of Vitamin C.

Vitamin B12 is a cofactor of enzyme L-methylmalonyl-COA mutase that converts L-methylmalonyl-COA to succinyl-COA that is used in one of the steps of the Krebs cycle. Krebs cycle is a series of chemical reactions that are used for the chemical breakdown of carbohydrates, fats, and proteins i-e through the oxidation of acetyl-coA that are derived from carbohydrates, fats, and proteins. Krebs cycle takes place in aerobic conditions. Without vitamin B12 our body is unable to produce energy by these series of reaction that takes place in Krebs cycle i-e unable to break sugar molecules that result in high blood glucose level that lead towards other health problems of the body.

  • Role of vitamin b12 in the healthy nervous system:

Vitamin b12 performs a crucial role in the maintenance of healthy nervous system of the body. It is important in the normal functioning and development of nerves in the brain. Its deficiency leads towards many psychological and neurological problems. Neurological problems include myelopathy, neuropathy, gait abnormalities, sensory disturbance and weakness. Psychiatric problems include cognitive and behavioral function disturbance that leads towards dementia. It is important for the synthesis and maintenance of myelin sheath that protects and covers the nerve fibers of both central and peripheral nervous system. The neurological and psychological problems are caused by vitamin B12 deficiency is due to the damage of myelin sheath.

Myelin sheath is a lipid rich substance that covers the nerves especially axons and provide protection and are important for the effective transmission of nerve flow.

“One carbon mechanisms” play important role in the proper functioning of central nervous system. This mechanism consists of many biochemical reactions that takes place in every cell and are important for the synthesis of DNA , RNA, myelin, phospholipids, neurotransmitters i-e acetylcholine, serotonin, dopamine, epinephrine that play essential role in synapses and also important for the maintenance of cognitive functions.

Vitamin b12 play important role in one carbon mechanism because it acts as cofactor in the synthesis of methionine.

  • Methionine is important for DNA methylation process
  • Methionine is also important for the prevention of the accumulation of harmful amino acids in the brain i-e homocysteine that are found in many neurodegenerative diseases.

Vitamin B12 also play important role in the process of myelin synthesis and stabilization because it acts as a coenzyme in the conversion of methyl melonyl CoA into succinyl CoA.

Deficiency of vitamin B12 leads towards the conversion of methyl melonyl CoA to methyl malonic acid (MMA) that acts as myelin destabilizer and involve in the production of abnormal fatty acids instead of myelin. These fatty acids combine with neuronal lipid and form a fragile myelin sheath i-e abnormal myelination occurs.

  • Role of vitamin B12 in bone marrow production of red blood cells :

Vitamin b12 is essential for healthy red blood cells production that is formed in bone marrow. Vitamin b12 plays important role in the maturation of erythroblasts and its deficiency leads towards macrocytic anemia that is the reversible cause of bone marrow failure. Anemia is a condition in which our body does not have enough red blood cells due to vitamin B12 and folate deficiency. These red blood cells are needed to transport oxygen throughout our body. Low levels of red blood cells result low levels of oxygen in the body especially in our tissues and bones that results in the change of the shape of new red blood cells. They become oval and large that causes the bone marrow to make low of red blood cells. Read here about Signs of Malnutrition.

  • Role of Vitamin B12 in bone regeneration:

Recently, vitamin b12 and folate are added to the list of bone protecting nutrient because of its role in detoxification of homocysteine. B vitamins play an important role in bone health in human studies. They are influencing bone structure, bone quality, bone mass and fracture risk particularly B2, B6 folate, and B12 plays protecting role in bone health. Read here about Rich Sources of Iron.

Nutrient deficiency increases the process of osteoporosis in elderly due to the increased risk of fall that causes hips fractures. Calcium and vitamin D are the essential nutrient in bone physiology that promotes bone health. Recently several other nutrients have reported that play important role in the physiology of bone health. B vitamins mainly B9(folate), B12 (Cobalamin) are the nutrient that are considered to play important role in bone health and fracture risk because these vitamins are involved in energy-producing metabolic pathways of carbohydrates, protein, and fats, in which they act as cofactors for many biochemical reactions that take place in the process of metabolism.

B12 and B9 are cofactors of the enzymes that are involved in the remethylation of homocysteine metabolism. Homocysteine is considered to increase the risk of fracture mainly hip fractures.in many observational studies, there is the association between B vitamins (B2, B6, folate and B12) and lower risk of osteoporosis that is demonstrated experimentally. Osteoblasts that are bone-forming cells require a sufficient amount of vitamin B12 to perform its function efficiently.

Deficiency of Vitamin B12 and its effect on the human body:

Vitamin B12 is an essential water-soluble vitamin that plays important role in the production of red blood cells, in DNA synthesis and in the maintenance of the healthy nervous system. Vitamin B12 is stored in body mainly in liver for longer time other B vitamins that are excreted out of the body through urine. Deficiency of vitamin B12 is mainly due to low intake of vitamin B12 through diet and due to trouble in the absorption of vitamin B12 from food. Read here about Rich Foods in Vitamin A.

Sign and symptoms of Deficiency of vitamin B12:

These are some signs and symptoms of vitamin B12 deficiency:

  • Fatigue, tiredness, weakness, and lightheadedness
  • Loss of appetite and gas
  • Weight loss
  • Diarrhea, constipation, and nausea
  • Nerve damaging problems like tingling sensations in the limbs, difficulty in walking and balance problems.
  • Weak muscle.
  • Dizziness
  • Headaches
  • Pale skin or jaundice
  • Breathlessness
  • Increased heart rate
  • Irritability
  • Smooth tongue or glossitis and mouth ulcer
  • Vision loss
  • Mood changes

Effects of Vitamin B12 deficiency in the body:

  • Anemia: Anemia mainly pernicious anemia is considered as the clinical manifestation of vitamin B12 deficiency. This type of anemia cause symptoms of fatigue, dizziness, and tachycardia.
  • Peripheral neuropathy: peripheral neuropathy is the condition of nerve damage by itself or due to the deficiency of myelin that is considered as the protecting covering of nerves that control the sensation and movement of the body.
  • Dementia: Dementia is a disease of memory loss and changes in the behavioral pattern. Vitamin B12 deficiency is recently discovered as one of the causes of dementia due to increase level of homocysteine in the blood.
  • Stroke: Vitamin B12 deficiency increases the risk of strokes due to raising levels of homocysteine in the blood.
  • Myelopathy: It is a disease due to the deficiency of vitamin B12  that cause the destruction of the parts of the spinal cord mainly myelin that controls the body’s sensation and balance.
  • Glossitis or tongue swelling: It is a condition of painful swelling of the tongue due to nutrient deficiency.

Who are at risk of Vitamin B12 deficiency

Below is the list of Individuals that are at great risk of Vitamin B12 Deficiency:

  • The Elderly
  • Those people who follow the strict vegan diet
  • Those who take long-term antacids drugs for heartburn and the drugs for diabetes type 2 and polycystic ovary syndrome
  • People who suffer from atrophic gastritis that is a condition of chronic inflammation of the cells of the stomach lining.
  • People who suffer from pernicious anemia in which the stomach cells that make intrinsic factors are destroyed that make it difficult for our body to absorb vitamin B12 i-e loss of parietal cells that are destroyed by body’s own immune system.
  • People who suffer from the condition that mainly affects the small intestine and stomach that include Crohn’s disease,
  • Celiac disease, parasite and bacterial growth, stomach disease and stomach ulcer.
  • People who suffer from immune system disorders like Grave’s disease
  • People who remove the parts of bowel through surgery that absorb vitamin B12
  • Poor dietary intake of vitamin B12 in infants and during pregnancy
  • Alcohol addiction

Diagnosis and treatment of vitamin B12 deficiency:

Different types of blood tests are conducted to check the number and appearance of red blood cells, level of folate, vitamin B12 and vitamin C in the blood.

Other tests include:

  • Schilling test
  • Methyl malonic acid test
  • Antibodies

Vitamin B12 deficiency is treated by ingesting the healthy diet that is rich in vitamin B12, through supplementation and injections of hydrocobalamin, by folic acid and iron supplementation for the treatment of folic acid deficiency

Benefits of Vitamin B12: Benefits for the Human Body

  • Vitamin B12 plays an essential role in energy production and in the proper metabolism of every cells.
  • Vitamin B12 is essential for red blood cells formation and in the synthesis of hemoglobin inside the red blood cells that transport oxygen throughout body.
  • Vitamin B12 is important for the maintenance of healthy nervous system i-e in the formation of myelin that protects the nerves of both central and peripheral nervous system.
  • It is involve in the process of methylation of DNA, in DNA synthesis and in the formation of neurotransmitters that are essential for proper cognitive functions.
  • Vitamin B12 is an important cofactor in the synthesis of methionine that is important for lowering the levels of homocysteine that are the major cause of many neurodegenerative diseases.

Vitamin B12 Overdose: vitamin b12 overdose Signs and Symptoms

Here are the results that you can encounter if vitamin b12 overdose occurs. Always follow RDA.

  • High doses of vitamin B12 can cause many side effects in patients like serious allergic reactions, high blood pressure, diarrhea, headaches, involuntary and uncontrollable movements etc.
  • To avoid the complication of vitamin B12 overdoses recommended values of Vitamin B12 should be taken.
  • Low levels of vitamin b12 increase the level of homocysteine in the blood that are the major factor of many neurodegenerative diseases.
  • Low levels of vitamin B12 results in impairment of red blood cells synthesis.
  • Deficiency of vitamin B12 leads towards fatigue, tiredness, memory loss etc.

I hope this article will help readers of the Nutrition Lab.

About the Author:

I am Zunaira Fazal, a student of Bachelors of Human Nutrition and Dietetics. One day I came across a newsfeed at my Facebook telling me that: “you are what u eat” and all at once an idea popped up at the surface of my mind about telling the world how amazing our life can be with a balanced diet. I got seated in front of my laptop to write down a piece of information, spreading health and fitness awareness in the community. I hope this article will help Individuals who are looking for Benefits of Vitamin B12.

“Prevention is better than cure”

My research about the vitamin B12 is going to blow your mind and you would not be able to resist yourself from jumping to a healthy lifestyle.

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  1. My name is Maryam Gul and I am student of human nutrition..
    Very informative article it is …!!
    I consume milk , meat especially organ meat , almonds and eggs to fulfill my vitamin B12 requirement…
    Thank You..

  2. A.O.A MY name is Rabeea Latif…i am student of human nutrition and dietetics at Bahauddin zakriya university multan…i use milk,eggs,nuts ,meats and vegetables as the good sources of vit B12.

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