Sources of Vitamin B12

Meat, eggs, fish and shellfish are good sources of vitamin B12. Saturation of vitamin B12 absorption is thought to occur at intakes of around 1.5 to 2.0 micrograms per meal, and this is due to the ability of intrinsic factor, the intestinal absorption transporter, to become saturated with the vitamin. Therefore high intakes of vitamin B12 in a single meal results in a sharp drop off in absorption as levels rise above 1.5 micrograms. In general the absorption of vitamin B12 from fish meat, sheep meat and chicken meat is about 42, 56-89 and 61-66 % respectively. In eggs, vitamin B12 is only absorbed at around 9 % suggesting bioavailability is low. In general around 50 % of ingested vitamin B12 is absorbed from animal foods in a standard mixed diet. A limited number of plants and green and purple lava (Nori) contain bioavailable vitamin B12 but the amount present is low. One good source of vitamin B12 for vegetarians and vegans is fortified breakfast cereals, although other vitamin B12 enriched foods are becoming available. 

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Watanabe, F. 2007. Vitamin B12 sources and bioavailability. Experimental biology and medicine. 232(10): 1266-1274

About Robert Barrington

Robert Barrington is a writer, nutritionist, lecturer and philosopher.
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