vitamin b12 gummies

Vitamin B₁₂, also known as cobalamin, is a water-soluble vitamin involved in metabolism.^[2] It is one of eight B vitamins. It is required by animals, which use it as a cofactor in DNA synthesis, and in both fatty acid and amino acid metabolism.^[3] It is important in the normal functioning of the nervous system via its role in the synthesis of myelin, and in the circulatory system in the maturation of red blood cells in the bone marrow.^[2][4] Plants do not need cobalamin and carry out the reactions with enzymes that are not dependent on it.^[5]

Vitamin B₁₂ is the most chemically complex of all vitamins,^[6] and for humans, the only vitamin that must be sourced from animal-derived foods or from supplements.^[2][7] Only some archaea and bacteria can synthesize vitamin B₁₂.^[8] Most people in developed countries^{[failed verification]} get enough B₁₂ from the consumption of meat or foods with animal sources.^[2] Foods containing vitamin B₁₂ include meat, clams, liver, fish, poultry, eggs, and dairy products.^[2] Many breakfast cereals are fortified with the vitamin.^[2] Supplements and medications are available to treat and prevent vitamin B₁₂ deficiency.^[2] They are taken by mouth, but for the treatment of deficiency may also be given as an intramuscular injection.^[2][6]

The most common cause of vitamin B₁₂ deficiency in developed countries is impaired absorption due to a loss of gastric intrinsic factor (IF) which must be bound to a food-source of B₁₂ in order for absorption to occur.^[9] A second major cause is age-related decline in stomach acid production (achlorhydria), because acid exposure frees protein-bound vitamin.^[10] For the same reason, people on long-term antacid therapy, using proton-pump inhibitors, H₂ blockers or other antacids are at increased risk.^[11] The diets of vegetarians and vegans may not provide sufficient B₁₂ unless a dietary supplement is consumed. A deficiency in vitamin B₁₂ may be characterized by limb neuropathy or a blood disorder called pernicious anemia, a type of megaloblastic anemia, causing a feeling of tiredness and weakness, lightheadedness, headache, breathlessness, loss of appetite, abnormal sensations, changes in mobility, severe joint pain, muscle weakness, memory problems, decreased level of consciousness, brain fog, and many others.^[12] If left untreated in infants, deficiency may lead to neurological damage and anemia.^[2] Folate levels in the individual may affect the course of pathological changes and symptomatology of vitamin B₁₂ deficiency.

Vitamin B₁₂ was discovered as a result of pernicious anemia, an autoimmune disorder in which the blood has a lower than normal number of red blood cells, due to a deficiency in vitamin B₁₂.^[5][13] The ability to absorb the vitamin declines with age, especially in people over 60 years old.^[14]

Vitamin B₁₂ is a coordination complex of cobalt, which occupies the center of a corrin ligand and is further bound to a benzimidazole ligand and adenosyl group.^[15] A number of related species are known and these behave similarly, in particular all function as vitamins. This collection of compounds is sometimes referred to as "cobalamins". These chemical compounds have a similar molecular structure, each of which shows vitamin activity in a vitamin-deficient biological system, they are referred to as vitamers. The vitamin activity is as a coenzyme, meaning that its presence is required for some enzyme-catalyzed reactions.^[10][16]

• adenosylcobalamin
• cyanocobalamin, the adenosyl ligand in vitamin B₁₂ is replaced by cyanide.
• hydroxocobalamin, the adenosyl ligand in vitamin B₁₂ is replaced by hydroxide.
• methylcobalamin, the adenosyl ligand in vitamin B₁₂ is replaced by methyl.

Cyanocobalamin is a manufactured form of B₁₂. Bacterial fermentation creates AdoB₁₂ and MeB₁₂, which are converted to cyanocobalamin by addition of potassium cyanide in the presence of sodium nitrite and heat. Once consumed, cyanocobalamin is converted to the biologically active AdoB₁₂ and MeB₁₂. The two bioactive forms of vitamin B
₁₂ are methylcobalamin in cytosol and adenosylcobalamin in mitochondria.

Cyanocobalamin is the most common form used in dietary supplements and food fortification because cyanide stabilizes the molecule against degradation. Methylcobalamin is also offered as a dietary supplement.^[10] There is no advantage to the use of adenosylcobalamin or methylcobalamin for treatment of vitamin B₁₂ deficiency.^[17][18][4]

Hydroxocobalamin can be injected intramuscularly to treat vitamin B₁₂ deficiency. It can also be injected intravenously for the purpose of treating cyanide poisoning, as the hydroxyl group is displaced by cyanide, creating a non-toxic cyanocobalamin that is excreted in urine.

"Pseudovitamin B₁₂" refers to compounds that are corrinoids with a structure similar to the vitamin but without vitamin activity.^[19] Pseudovitamin B₁₂ is the majority corrinoid in spirulina, an algal health food sometimes erroneously claimed as having this vitamin activity.^[20]

Vitamin B₁₂ deficiency can potentially cause severe and irreversible damage, especially to the brain and nervous system.^[6][21] At levels only slightly lower than normal, a range of symptoms such as feeling tired, weak, feeling like one may faint, dizziness, breathlessness, headaches, mouth ulcers, upset stomach, decreased appetite, difficulty walking (staggering balance problems),^[12][22] muscle weakness, depression, poor memory, poor reflexes, confusion, and pale skin, feeling abnormal sensations, among others, may be experienced, especially in people over age 60.^[6][12][23] Vitamin B₁₂ deficiency can also cause symptoms of mania and psychosis.^[24][25] Among other problems, weakened immunity, reduced fertility and interruption of blood circulation in women may occur.^[26]

The main type of vitamin B12 deficiency anemia is pernicious anemia.^[27] It is characterized by a triad of symptoms:

1. Anemia with bone marrow promegaloblastosis (megaloblastic anemia). This is due to the inhibition of DNA synthesis (specifically purines and thymidine).
2. Gastrointestinal symptoms: alteration in bowel motility, such as mild diarrhea or constipation, and loss of bladder or bowel control.^[28] These are thought to be due to defective DNA synthesis inhibiting replication in tissue sites with a high turnover of cells. This may also be due to the autoimmune attack on the parietal cells of the stomach in pernicious anemia. There is an association with gastric antral vascular ectasia (which can be referred to as watermelon stomach), and pernicious anemia.^[29]
3. Neurological symptoms: sensory or motor deficiencies (absent reflexes, diminished vibration or soft touch sensation) and subacute combined degeneration of the spinal cord.^[30] Deficiency symptoms in children include developmental delay, regression, irritability, involuntary movements and hypotonia.^[31]