About vitamin B12
B12 is an essential vitamin and belongs to the water-soluble vitamins. That it is essential means that the body cannot produce it itself and that it must be ingested through the diet.
One of the most important functions of B12 is the production of DNA. If the body cannot produce DNA, the cells cannot divide, which is necessary for broken and malfunctioning cells to be replaced with new ones. B12 is also needed for the myelination of the nerves (formation of special fats that insulate the nerves) and for the breakdown of homocysteine that is formed naturally during protein metabolism.
This vitamin B12 test measures Holotranscobalamin, which is the active form of B12 in the body. Active B12 is a safe marker to detect if there is a B12 deficiency as it has a higher sensitivity than MMA (methyl malonate).
B12 – special absorption capacity
B12 belongs to the water-soluble vitamins but is not really soluble in water or fat-soluble substances. The uptake of B12 into the body requires a special mechanism, the so called Intrinsic Factor (IF). Intrinsic factor is produced by oxygen-forming cells in the wall of the stomach and acts as a carrier for B12 into the blood. Intrinsic Factor attaches to B12 and is transported up through the intestinal wall, through the blood and to the liver where it’s either stored or transported on to parts of the body that need the vitamin.
B12 is stored in the liver and can be stored there up to 20 years. Unlike other B vitamins, the body does not need a regular supply of B12 if the depot is full due to the liver’s storage capacity. At the same time, it is important to remember that certain groups of people are at high risk for a deficiency of B12. In addition to vegans, alcoholics and people who have undergone gut surgery are also at high risk of developing B12 deficiency. The reason is that these groups may have a reduced production of Intrinsic Factor and without this, the body cannot absorb B12 in the gut.
Vegans and B12 – deficiency
Vitamin B12 is naturally present in foods of animal origin, which means that vegans are at high risk of developing a deficiency. Common symptoms are fatigue, weakness, pale skin, heart palpitations and mental problems like depression and memory loss. Severe deficiency can lead to pernicious anemia (special type of anemia), neurological symptoms that manifest themselves in the form of tingling and muscle weakness and which can also turn into a so called “burning feet syndrome” (this is du to that myelin cannot form and isolate the nerves properly). For vegans, B12 supplements are essential. How low the levels are in the body largely depends on the depots that were stored in the liver at the time of the change to a vegan diet.