What is Vitamin B12 for Nutritional Enrichment?

What is Vitamin B12
Vitamin B12 (Cyanocobalamin) is a water-soluble vitamin also known as cyanocobalamin, also known as animal protein factor, is a general term for a group of vitamins containing active substances similar to cyanocobalamin. It is the only water-soluble vitamin that contains metal ions and is one of the essential vitamins. The synthetic product of vitamin B12 is cyanocobalamin, which is formed during the dissociation of cobalamin. It is a red crystal that is very stable and is used for food fortification and nutritional supplementation. Plant cells cannot synthesize vitamin B12, so most plant foods do not contain vitamin B12, which is concentrated in animal tissues.
Physiological functions of vitamin B12
1. Increase the utilization rate of folic acid and folic acid together with the synthesis of methionine (synthesized from homocysteine) and choline, the production of purines and pyrimidines in the process of the synthesis of cyanocobalamin Schein base precursor substances such as methylcobalamin and coenzyme B12, involved in the methylation process of many important compounds. In vitamin B12 deficiency, the transfer of methyl groups from methyltetrahydrofolate is reduced, turning folic acid into an unavailable form and leading to folate deficiency.
2. Maintenance of nerve myelin metabolism and function When vitamin B12 is deficient, it can cause neurological deficits, spinal cord degeneration, and can cause severe psychiatric symptoms. Vitamin B12 deficiency can lead to peripheral neuritis. Early manifestations of vitamin B 12 deficiency in children are abnormal mood, dull expression, slow response and finally anemia.
3. It promotes the development and maturation of red blood cells by converting methylmalonyl coenzyme A into succinyl coenzyme A, which participates in the tricarboxylic acid cycle, in which succinyl coenzyme A is related to the synthesis of hemoglobin.
4. Vitamin B12 is involved in the synthesis of deoxyribonucleic acid (DNA), the metabolism of fats, carbohydrates and proteins, and increases the synthesis of nucleic acids and proteins.
Vitamin B12 deficiency disease
1. Common causes of vitamin B12 deficiency (1) insufficient intake, such as long-term vegetarians; (2) acquired malabsorption, such as pancreatic, gastric, hepatic or intestinal diseases; (3) increased demand for vitamin B12, such as pregnancy, postnatal period, tapeworms, etc.; (4) congenital obstacles to the metabolism step of vitamin B12, such as inborn deficiency of internal factors. (5) Pharmacogenetic: studies have found that oral metformin leads to lower serum vitamin B12 levels.
2. Common diseases of vitamin B12 deficiency Vitamin B12 deficiency is mainly reflected in the blood, metabolism and nervous system, which can lead to hyperhomocysteinemia (Hhcy), pernicious anemia, subacute combined degeneration, mental depression, methylmalonic acidemia, vascular dementia and Alzheimer’s disease and other diseases.
3. Vitamin B12 toxicity is relatively low according to reports of daily oral up to 100μg, no significant adverse reactions. Note: The nutritional status of vitamin B12 can be determined by testing serum vitamin B12 concentration, serum holotranscobalamin II (holo Tc II), serum holobinding cochineal, serum homocysteine and methylmalonic acid.
Reference Intake and Food Sources
The human body requires very little vitamin B12. The Recommended Dietary Allowance (RDA) for vitamin B12 ranges from 0.9 μg per day in early childhood to 2.4 μg per day in adulthood, which is sufficient to meet the needs of 97.5% of the population. The RDA for pregnant women is 6 μg per day, and although the RDA has not been increased for the elderly, they are prone to vitamin B12 malabsorption and are advised to increase their intake of vitamin B12-fortified foods or supplements. Our proposed AI for vitamin B12 is 2.4 μg/d for adults.
Dietary vitamin B12 is derived from animal foods, with the main food sources being meat, animal offal, fish, poultry, shellfish and eggs, and lesser amounts in milk and dairy products (Table 1). Plant foods are essentially free of vitamin B12.
Table 1 Vitamin B12 content of selected foods (μg/100g)

Note: Cited in Ensminger AH et al. 1989.American Encyclopedia of Food and Nutrition Selected (5) Food Composition.
Vitamin B12 as a nutrient fortifier can be used in which foods