Vitamin B12 is a water-soluble vitamin, its absorption and metabolism differ greatly from other water-soluble vitamins (B vitamins and vitamin C). Vitamin B12´s name cobalamin comes from its mineral cobalt´s content.
MOST IMPORTANT TASKS OF VITAMIN B12
- normal metabolism of amino acids -> formation of methionine from homocysteine (both are amino acids). Amino acids are the building block for proteins.
- prevention of anemias -> in case of vitamin B12 deficit anemia, red blood cells are bigger in size than normal (also called megaloblastic anemia), vitamin B12 together with folate participates in formation of red blood cells and in case of vitamin B12 deficiency, metabolism of folate is also disturbed
- normal maintenance of nerve tissue -> necessary for the formation of myelin (substance surrounding the nerve tissue). In case of myelin damage (e.g. in case of vitamin B12 deficiency), normal operation of nerve signals is disturbed and a person may have different neurological symptoms (nerve system disorders)  
HOW DOES VITAMIN B12 GET ABSORBED?
- Vitamin B12 is first attached to an intrinsic factor IF glycoprotein in the stomach -> without IF glucoprotein vitamin B12 does not get absorbed in an active way
- After being attached to the glycoprotein, vitamin B12 is absorbed in the final end of the small intestine in ileum (compared to other essential nutrients that are mainly absorbed in the beginning of the small intestine, in duodenum) 
- In case active absorption is disturbed, vitamin B12 still gets absorbed by passive mechanism throughout the whole small intestine area by 1% 
In case of pernicious anemia glycoprotein called intrinsic factor (IF) is not formed in the stomach, thus the absorption of vitamin B12 is disturbed. This leads to pernicious anemia due to lack of vitamin B12. The disease may be hereditary but it can also be associated with different autoimmune endocrine diseases, e.g. type I diabetes and thyroid diseases (diseased linked to hormonal disruption). Such people get vitamin B12 through injections .
Did you know that…
Vitamin B12 is only absorbed within 2 µg by active mechanism. This is due to intrinsic factor glycoprotein receptors´ ability to bind maximum of 2 µg of vitamin B12. All the rest of the vitamin that does not get bind to the glycoprotein gets absorbed in the whole small intestine area by passive mechanism 1%. The main contribution of vitamin B12 in food supplements comes from the passive mechanism. If a food supplement consists of 100 μg of vitamin B12, 2 μg is absorbed by active + 1% of 98 μg is absorbed by passive mechanism, total approximately 2,98 μg gets absorbed. Vitamin B12´s absorption from food is about 50% .
GOOD SOURCES OF VITAMIN B12
Vitamin B12 is found in its active form in foods of animal origin. Certain types of seaweed are an exception, but due to uncertain amount of iodine, consumption of seaweed for vitamin B12 is not suggested. Plant-based food includes B12 analogues that lack the properties of active vitamin B12. However, B12 is added to many plant-based foods.
Daily dosage of vitamin B12 differs within countries. In Estonia, it is 0,5–0,8 μg for children under 6 year, 1,3 μg for children of age 6–9 and starting from 10 year old children and adults, the daily suggested dosage is 3 μg .
|Food||Vitamin B12 content (mcg) for 100 g|
|Boiled beef liver
Animal liver in general
Smoked Baltic herring
Warm smoked salmon
Ovenfish in general
WHAT HAPPENS TO THE VITAMIN B12 THAT GETS ABSORBED?
Already absorbed vitamin B12 is binded with a protein called transcobalamin and holotranscobalamin complex is formed (holotranscobalamin is the active form of vitamin B12 that can be measured from blood). Unlike other B group vitamins, our bodies have good vitamin B12 stores– 2–5 mg, i.e. 2000–5000 μg. Such supplies are enough for many years before vitamin B12 deficit develops. For instance, newborns have vitamin B12 stores of approximately 25 μg that are enough for the first year. The stores are mainly in the liver and kidneys .
HOW MUCH VITAMIN B12 EXITS THE BODY EVERY DAY?
Daily about 0,1–0,2% of our body´s vitamin B12 stores are depleted, i.e. around 2–5 μg. Excretion happens mainly through bile and kidneys. Vitamin B12 that is excreted from bile to the small intestine gets reabsorbed 65–75%, thus stool consists of a very small amount of vitamin B12 .
READ MORE ABOUT B12 DEFICIENCY AND POSSIBLE REASONS FROM HERE.
Nôgel VITAMIN B12 DROPS
- for infants and children 1 drop consists of 100 μg of MecobalActive® methylcobalamin – one of the purest vitamin B12 forms produced in an environmentally friendly way
- for the whole family 1 drop consists of 500 μg of vitamin B12
- only three ingredients: water, B12 and organic lemon juice to guarantee shelf life
- for infants and children – the first pure liquid methylcobalamin product in Estonia that consists of a small amount of vitamin B12 -> it is easier for medical staff to make dosing guidelines and the risk for over- or underdosing (when one drop is given less or more) is small
- methylcobalamin is the safest form of vitamin B12 for infants, toddlers, pregnant and nursing women
- thanks to its pink colour (methylcobalamin´s powder is pink) it is easy to see if a drop is missed
- 1 bottle = 330 drops
- products are meant for oral consumption for absorption through small intestine (drop on the tongue) or to dose below tongue for absorption through mucosa
 A. Aro, M. Mutanen, M. Uusitupa. Nutrition Science, 4.–7.volume, 2017.
 Pernicious anemia. Hematology and Onkology Clinic of University of Tartu.
 Vitamin B12. National Institute for Health Development in Estonia.
 Fineli. Finnish Food Authority´s maintained official database of food content.