Vitamin B12, Average Intakes And RDAs


“Methylcobalamin (shown) is a form of vitamin B12. Physically it resembles the other forms of vitamin B12, occurring as dark red crystals that freely form cherry-colored transparent solutions in water.”  – Wikipedia

Here’s a collection of average intakes and RDAs for vitamin B12. If you know of any more, please comment and I’ll update this:

Okinawa intake 1949: 0.6 mcg
Japan intake 1950: 4.0 mcg
Japan RDA 2.2 mcg
UK NHS recommendation: 1.5 mcg
US RDA: 2.4 mcg
US intake: 4.3 mcg
Proposed US RDA: 4 to 7 mcg

The intakes don’t represent daily doses, especially for people like the Okinawans who didn’t eat animal food every day. They’re just averages.

It’s clear that we don’t need very much vitamin B12 …  mcg stands for microgram which is 1/1000th of a milligram, and a milligram is 1/1000th of a gram. But we do need some.

I’ve found a good way to get enough but not too much is by using drops.* One drop contains about 40 mcg, a relatively small amount but difficult to find in high-dose pills.

* Liquid vitamin B12, methylcobalamin, serving size: 1 ml (25 drops) provides 1000 mcg B12. This is a 2 fluid ounce bottle I bought for about $8.

One thought on “Vitamin B12, Average Intakes And RDAs

  1. RB

    Dr. T. Collin Campbell has some interesting info on this blog about B12 including this on B12 supplementation and B12 absorption:
    “For the general adult population, a daily dose of the smallest available tablet of B12 (usually 100 mcg) should be sufficient. You require just a few micrograms a day. Your body will absorb only a very small part of that pill. The reason for this low absorption is that there is only enough intrinsic factor (the body’s chemical that shuttles B12 into your gut cells) excreted per meal to absorb 2-4 micrograms of B12. ” Entire blog is at:

    It is interesting that the body can only absorb its daily need in B12 no matter the dosage of B12 supplement taken. More isn’t better. It is just a waste. Why the mega-doses?


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