Vitamin B12, also known as cobalamin, is a water-soluble vitamin essential for human health.
Vitamin B12 is produced in nature by some bacteria. These bacteria are found in the gut of humans and animals.
Many animals can re-absorb the vitamin B12 synthesised by fermentation in their gut. They store it in the liver and muscles, and some pass the vitamin into their eggs and milk.
In contrary, humans cannot significantly re-absorb the vitamin B12 produced in their gut because that fermentation happens in the colon. Therefore, we must obtain it from our food (1).
Algae and phytoplankton also contain some vitamin B12. They obtain the vitamin from symbiosis with bacteria. Fish is a good source of vitamin B12 and obtain it by eating these phytoplankton.
Fermented plant foods such as tempeh also contain vitamin B12 produced by fermentation.
Vitamin B12 contributes to many bodily functions, including:
Vitamin B12 is required for the development and function of the central nervous system via its role in the synthesis of myelin which is substance that surrounds nerve fibres to insulate them and increase the rate of electrical impulses.
Vitamin B12 is essential for the formation of red blood cells.
Vitamin B12 is involved in DNA synthesis and regulation.
Recommended Daily Allowance for a 44-year-old male moderately active, weighting 70 kg and 175 cm tall is 2.4 µg (2).
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Vitamin B12 deficiency may cause the following (3) :
The FNB (Food and Nutrition Board of the Institute of Medicine) did not establish an upper limit for vitamin B12 because of its low potential for toxicity. Even at large doses, vitamin B12 is generally considered to be safe because the body does not store excess amounts (4).