Vitamin B12, also known as cobalamin, is an essential nutrient which the body cannot produce itself (1-2).
Though certain bacteria present in the human colon are able to synthesise vitamin B12, the vitamin cannot normally be absorbed as it produced too far from the body’s main absorption site (the terminal ileum in the small intestine) (3).
Yet vitamin B12 is essential to human health. This water-soluble vitamin actually supports normal energy metabolism, and immune system, nervous system and psychological function. It is also known for helping to reduce fatigue.
It is found primarily in dairy products, meat, fish and eggs, in other words, animal-source foods. That’s why vegetarians and vegans may need to supplement with B12.
The recommended daily intake (RDI) for vitamin B12 is around 2.4 micrograms (µg) for an adult. There are no known risks associated with having too much of this vitamin: any excess B12 is stored in the liver to prevent deficiency.
Here, in reverse order, are the 10 best sources of vitamin B12:
Last place in our top 10 goes to eggs which contain 0.6µg of vitamin B12 per 100g (that’s still a good 25% of the recommended daily intake).
Milk contains 1.2µg of vitamin B12 per 100g (that’s 50% of the RDI). And some studies suggest that the vitamin B12 in dairy products is more easily absorbed by the body than that found in meat, fish or eggs.
Cheese has 1-1.5µg of vitamin B12 per 100g (that’s between 40% and 60% of the RDI).
Salmon contains 3.2µg of vitamin B12 per 100g (that’s 133% of the RDI).
Just ahead of salmon is another fish, trout, with 5.4µg of vitamin B12 per 100g (that’s 225% of the RDI).
Sardines contain 8.9µg of vitamin B12 per 100g (that’s 370% of the RDI).
Crab contains a high level of B12 with 11.5µg of the vitamin per 100g (that’s 479% of the RDI).
Oysters take bronze position with 16µg of vitamin B12 per 100g (that’s 667% of the RDI).
At second place in our top 10 is liver which is extremely rich in B12: beef liver, for example, contains 60-100µg of vitamin B12 per 100g (that’s around 2500%-4000% of the RDI).
And finally, the gold medal goes to clams, which contain 98.9µg of vitamin B12 per 100g (that’s more than 4000% of the RDI). So be sure to include these little shellfish on your menu from time to time…
If you want an easier and faster way of boosting your B12 intake, then dietary supplements can help. But which form should you choose?
In addition to adenosylcobalamin and hydroxocobalamin, there are two main forms of vitamin B12 which are used to produce supplements: cyanocobalamin and methylcobalamin.
Cyanocobalamin is a synthetic form. Its strengths are that it offers good heat stability and is low in cost. However, several animal and human studies have shown it to be less well-absorbed at a cellular level, with lower tissue retention and a higher rate of urinary excretion. The fact that cyanocobalamin has a cyanide group also places a slight question mark over its complete safety.
Methylcobalamin, on the other hand, is a natural form present in our diet. Superior to cyanocobalamin, it is an active form bio-identical to vitamin B12 which acts as a coenzyme in cell cytoplasm. The fact that is very well metabolised makes it a better choice when it comes to supplementing with vitamin B12 (try, for example, the product Methylcobalamine).
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