Vitamin B12 can be an important nutrient for people suffering from environmental illnesses, both because deficiency is common and because of the metabolic functions it performs in the body.
The absorption of vitamin B12 is complex. Adequate stomach acid and protein-digesting (proteolytic) enzymes are required to liberate it from the high protein foods in which it is found. Once in its free form it is Bound to special proteins secreted in the stomach called R-proteins. At the same time another substance called intrinsic factor (IF) is also secreted. In the duodenum (upper small intestine) proteolytic enzymes secreted by the pancreas release vitamin B12 from the R-proteins and it then binds to IF. Vitamin B12 is finally absorbed in the final section of the small intestine (the ileum) and this can only take place if it is bound to IF. IF also protects B12 from being metabolised by bacteria in the small intestine.
So, you can see that common problems in those with environmental illnesses could interfere with vitamin B12 absorption and lead to deficiency. Low stomach acid (hypochlohydria) is common and could reduce the release of B12 from food and the secretion of R-proteins and IF. Equally inadequate production of enzymes by the pancreas can be a problem and prevent the splitting of B12 from R-proteins, preventing it from binding to IF. Then there is the common problem of gut dysbiosis. Overgrowth of bacteria and yeast in the small intestine can result in these microorganisms "stealing" the B12 that is consumed. Gut dysbiosis and other factors can also result in leaky gut syndrome and impaired absorption of B12.
The liver maintains a store of B12 that can last anywhere up to three or four years so it can take some time for symptoms to show up and a deficiency may also be masked by high folic acid intake due to an overlap in functions.
Vitamin B12 is required by the body for a variety of reasons. It is needed for the production of red blood cells (due to its role in DNA synthesis) and deficiency can result in megaloblastic anaemia, the production of large and dysfunctional red blood cells. This impacts oxygen delivery to cells and causes symptoms such as fatigue. Problems with oxygen delivery to cells and tissue oxygenation are known to be common in illnesses such as chronic fatigue syndrome (ME/CFS) so B12 deficiency can further exacerbate this. In addition, B12 is directly involved in fatty acid synthesis and energy production. The predominant reason why B12 injections have traditionally been used as treatments for ME/CFS and other fatiguing conditions.
Vitamin B12 is also required to maintain the health of the nervous system. Through its role in fatty acid synthesis it plays a vital role in the production of a fatty substance called myelin that insulates and protects nerve cells. Deficiency can result in numerous neurological symptoms including loss of coordination and less of the sense of touch. There is also an association between low levels of B12 and depression.
Finally B12 is involved in the methylation cycle and the recycling of folic acid in the body. Methylation is a chemical reaction vital to the production of many important chemicals in the body including neurotransmitters that regulate mood and mental functioning as well as the production of the important antioxidant glutathione. Methylation itself is a process used to detoxify toxins, enabling them to be excreted from the body.
Vitamin B12 is found predominantly in animal foods including fish and shellfish, meat (particularly liver), poultry, eggs, and dairy products. Plant sources such as fermented soya products (tempeh, miso etc), seaweed, and algae have been proposed as sources suitable for vegans but testing has shown no plant foods can be relied upon for vitamin B12.
Beneficial bacteria present in the colon including Lactobacilli and Bfidobacteria produce vitamin B12 but B12 is not absorbed from the colon. Vegans therefore need to consume adequate amounts of fortidied foods and/or take supplements (containing B12 produced by bacteria or yeast).
Supplements of vitamin B12 are available in a variety of forms. Cyanocobalamin is the most widely available and cheapest form but not the most active in the body. Methylcobalamin is one of the biologically active forms of B12, is normally produced from cyanocobalamin in the liver, and is now available in supplemental form at a slightly higher price.
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