Vitamin B12 Some edits by User Mrt3366 lack proper references and are factually incorrect The claim that Bacteria are the only sources of vitamin B12 vitamin B12 is false it is produced by a unicelular alga by example Pleurochrysis Carterae Fortified breakfast cereals don t offer vitamin B12 vitamin B12 from plants they have it added as a supplement It is recommended for vegans to take supplements as such as a minimum dosage can be reliably maintained The human gut also contains B12 synthesizing bacteria living from the mouth to the anus looks false The old 1980 reffered study only reffered to small bowels and it was falsified since Claims of intestinal B 12 production may be based on insufficient evidence Albert et al 1980 is sometimes cited as evidence that B 12 producing bacteria can exist in the small intestine Sometimes explicit claims are made e g that intestinal bacteria allegedly can produce adequate B 12 Baker 1981 and Nutrition Reviews 1980 are related citations that comment on Albert et al 1980 However a careful reading of Albert et al 1980 shows that it used bacteriological assays which are of lower reliability to measure B 12 levels Specifically the most accurate bacteriological assay they used is Ochromonas malhamensis Note that Ochromonas is the most accurate bacterial assay method for B 12 however even it may report values for some analogues as part of its B 12 results Schneider and Stroinski 1987 Tables 3 2 5 3 to 5 5 pp 56 57 119 123 Herbert and Das 1994 p 405 apparently regard all the bacterial assay methods as being less reliable than differential radioassay also see Herbert et al 1984 and Herbert 1988 for related information Additionally the data obtained in Albert et al 1980 comes from isolated bacterial cultures Therefore it is unclear whether the bacteria would produce similar amounts of B 12 under the conditions present in the intestines This point is discussed in Albert et al 1980 but is sometimes ignored by dietary advocates with an ideological interest in minimizing the requirement for B 12 in the diet The bottom line in the paper of Albert et al 1980 is that it shows certain intestinal bacteria might produce B 12 but it is unclear whether how much might be produced and absorbed under actual conditions in the small intestine The last paragraph contain only straight propaganda from 2 MD personal pages contradicting the necesity of the vitamin without any reference to reliable sources The editor was also part of a dispute on the Vitamin B12 article Preceding unsigned comment added by talk contribs Algae acquire vitamin B12 through a symbiotic relationship with bacteria Individually algae and bacteria make interesting organisms to study Bacteria are organisms that can be found living in a range of different environments Besides being organisms capable of causing disease in humans they are also vital to the cycling of nutrients within the environment Algae are organisms capable of fixing carbon through photosynthesis within aquatic systems At the same time they are important to study because with increased nutrient loads to bodies of water can cause algal blooms which can lead to eutrophication This reduces the amount of dissolved oxygen available for use by fish and other aquatic organisms Bacteria and algae can coexist within biofilms Biofilms can help reduce the effects of external factors to produce areas that can allow for growth of specific bacterial populations and make conditions favorable for certain bacterially mediated processes such as denitrification your source however didn t exactly say that B12 is produced by a unicelular alga It said Talk