11. Vitamin B12 is produced by the fermentation of bacteria and microorganisms.12. _Vitamin B12 : RDA, 2.4 micrograms, the amount in 3 ounces of beef. 13. Vitamin B12 and folate may be important for cognitive function in old age.14. This can be one of the causes of vitamin B12 deficiency. 15. A doctor injected Williams with two shots of vitamin B12 that contained morphine. 16. The illness was later determined to be a vitamin B12 deficiency. 17. They are also a good source of vitamin D, calcium, vitamin B12 , and protein. 18. Years later it was discovered that the required factor was vitamin B12 , or cyanocobalamin. 19. Deficiencies in zinc, iron and vitamin B12 are, however, common nutritional deficiencies in vegetarians. 20. Vitamin B12 is depleted by recreational use of nitrous oxide, and is thereby useful.
