Cobalamin
Cobalamin, also known as vitamin B12, is a water-soluble vitamin that is essential for various bodily functions. It is involved in the metabolism of every cell of the human body, particularly affecting DNA synthesis and regulation, fatty acid synthesis, and energy production. Cobalamin is also crucial for the formation of red blood cells, the maintenance of the nervous system, and the health of nerve tissue[1][2][3][4][6][12][17].
Vitamin B12 is naturally found in animal products such as fish, meat, poultry, eggs, milk, and milk products. It is not generally present in plant foods, although some fortified breakfast cereals and nutritional yeast products can be good sources, especially for vegetarians and vegans[3][4][13][17][20]. The body can store vitamin B12 for years in the liver, and it is absorbed in the distal half of the ileum after binding to intrinsic factor, a protein secreted by the stomach[6][12][17].
Deficiency in vitamin B12 can lead to a range of symptoms, including fatigue, weakness, anemia, nerve damage with numbness and tingling in the hands and feet, memory loss, confusion, and in severe cases, dementia and depression[1][3][5][7][9][10][11][17]. The deficiency can be caused by various factors, including inadequate dietary intake, poor absorption due to conditions like Crohn's disease or celiac disease, or lack of intrinsic factor, which can lead to pernicious anemia[5][7][9][11][12][14][15][17].
The recommended dietary allowance (RDA) for vitamin B12 varies by age, sex, and life stage, with adults requiring 2.4 micrograms per day[6][17][20]. Pregnant and lactating women have slightly higher needs[6][17]. There is no established toxic level for vitamin B12, and high dosages are not necessarily harmful, but some evidence suggests that supplements of 25 micrograms per day or higher may increase the risk of bone fractures[17].
Vitamin B12 supplements are available in various forms, including oral supplements, injections, and nasal sprays. In cases of severe deficiency, especially when due to inadequate intrinsic factor, doctors may prescribe B12 injections[6][17]. It is important for individuals at risk of deficiency, such as older adults, strict vegetarians, and those with absorption issues, to ensure adequate intake of vitamin B12 through diet or supplementation[3][4][13][14][15][17][20].
Citations:
[1] https://www.nhs.uk/conditions/vitamin-b12-or-folate-deficiency-anaemia/symptoms/
[2] https://www.ncbi.nlm.nih.gov/books/NBK559132/
[3] https://www.healthline.com/nutrition/vitamin-b12-deficiency-symptoms
[4] https://www.netmeds.com/health-library/post/vitamin-b12-functions-food-sources-deficiencies-and-toxicity
[5] https://www.hopkinsmedicine.org/health/conditions-and-diseases/vitamin-b12-deficiency-anemia
[6] https://ods.od.nih.gov/factsheets/VitaminB12-HealthProfessional/
[7] https://www.webmd.com/diet/vitamin-b12-deficiency-symptoms-causes
[8] https://my.clevelandclinic.org/health/diseases/22831-vitamin-b12-deficiency
[9] https://www.ncbi.nlm.nih.gov/books/NBK441923/
[10] https://www.health.harvard.edu/blog/vitamin-b12-deficiency-can-be-sneaky-harmful-201301105780
[11] https://www.nhsinform.scot/illnesses-and-conditions/nutritional/vitamin-b12-or-folate-deficiency-anaemia/
[12] https://en.wikipedia.org/wiki/Vitamin_B12
[13] https://www.webmd.com/diet/what-are-plant-food-sources-vitamin-b12
[14] https://www.medicalnewstoday.com/articles/219822
[15] https://www.mountsinai.org/health-library/supplement/vitamin-b12-cobalamin
[16] https://www.webmd.com/diet/health-benefits-vitamin-b12
[17] https://www.hsph.harvard.edu/nutritionsource/vitamin-b12/
[18] https://www.health.com/vitamin-b12-7252832
[19] https://www.healthline.com/nutrition/vitamin-b12-benefits
[20] https://www.mountsinai.org/health-library/nutrition/vitamin-b12