Based on two biomarkers of functional vitamin B12 (cobalamin) status, B12 recommendations formulated more than a half century ago may need to be updated.
Vitamin B12 Recommendation Change
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How much B12 do we need? Well, the recommended dietary allowance is 2.4 micrograms; 2.4 millionths of a gram every day. That number, I was surprised to learn, was based on a study of just seven people, performed so long ago that four were described as, capital “N” “Negroes.” Both society and science have moved on a bit since then, and the new numbers were recently published, and it appears “4 to 7” is the new 2.4.
How did they come up with that? Well, two reactions B12 facilitates are the metabolism of methylmalonic acid and homocysteine. And so, if we’re B12-deficient, these two compounds can build up in our bloodstream, because there isn’t enough B12 to run these reactions. So, low levels of MMA and homocysteine can be a sign of good B12 status.
And as you can see, 2.4 micrograms is good in terms of lowering methylmalonic acid levels and homocysteine, but 4 appears to be better. These biomarkers of functional B12 status hadn’t even been discovered when quote/unquote “Negroes” walked the earth. And once you hit 7 a day, you basically max out, so there’s no need to get more—though there appears to be no danger in doing so; you just pee the excess out.
So that’s where they got the new 4 to 7 a day recommendation, though, as we’ll see, we may need to take much more than that to absorb that amount.
To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video. This is transcript contributed by Bruce A. Hamilton.
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- Dietary Reference Intakes for Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline: A Report of the Standing Committee on the Scientific Evaluation of Dietary Reference Intakes and its Panel on Folate, Other B Vitamins, and Choline and Subcommittee on Upper Reference Levels of Nutrients, Food and Nutrition Board, Institute of Medicine. ISBN: 0-309-59725-0 (1998).
- Darby WJ, Bridgforth EB, Le Brocquy J, Clark SL Jr, De Oliveira JD, Kevany J, Mcganity WJ, Perez C. Vitamin B12 requirement of adult man. Am J Med. 1958 Nov;25(5):726-32.
- Bor MV, von Castel-Roberts KM, Kauwell GP, Stabler SP, Allen RH, Maneval DR, Bailey LB, Nexo E. Daily intake of 4 to 7 microg dietary vitamin B-12 is associated with steady concentrations of vitamin B-12-related biomarkers in a healthy young population. Am J Clin Nutr. 2010 Mar;91(3):571-7. Epub 2010 Jan 13.
How much B12 do we need? Well, the recommended dietary allowance is 2.4 micrograms; 2.4 millionths of a gram every day. That number, I was surprised to learn, was based on a study of just seven people, performed so long ago that four were described as, capital “N” “Negroes.” Both society and science have moved on a bit since then, and the new numbers were recently published, and it appears “4 to 7” is the new 2.4.
How did they come up with that? Well, two reactions B12 facilitates are the metabolism of methylmalonic acid and homocysteine. And so, if we’re B12-deficient, these two compounds can build up in our bloodstream, because there isn’t enough B12 to run these reactions. So, low levels of MMA and homocysteine can be a sign of good B12 status.
And as you can see, 2.4 micrograms is good in terms of lowering methylmalonic acid levels and homocysteine, but 4 appears to be better. These biomarkers of functional B12 status hadn’t even been discovered when quote/unquote “Negroes” walked the earth. And once you hit 7 a day, you basically max out, so there’s no need to get more—though there appears to be no danger in doing so; you just pee the excess out.
So that’s where they got the new 4 to 7 a day recommendation, though, as we’ll see, we may need to take much more than that to absorb that amount.
To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video. This is transcript contributed by Bruce A. Hamilton.
Please consider volunteering to help out on the site.
- Dietary Reference Intakes for Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline: A Report of the Standing Committee on the Scientific Evaluation of Dietary Reference Intakes and its Panel on Folate, Other B Vitamins, and Choline and Subcommittee on Upper Reference Levels of Nutrients, Food and Nutrition Board, Institute of Medicine. ISBN: 0-309-59725-0 (1998).
- Darby WJ, Bridgforth EB, Le Brocquy J, Clark SL Jr, De Oliveira JD, Kevany J, Mcganity WJ, Perez C. Vitamin B12 requirement of adult man. Am J Med. 1958 Nov;25(5):726-32.
- Bor MV, von Castel-Roberts KM, Kauwell GP, Stabler SP, Allen RH, Maneval DR, Bailey LB, Nexo E. Daily intake of 4 to 7 microg dietary vitamin B-12 is associated with steady concentrations of vitamin B-12-related biomarkers in a healthy young population. Am J Clin Nutr. 2010 Mar;91(3):571-7. Epub 2010 Jan 13.
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Vitamin B12 Recommendation Change
LicenseCreative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)
Content URLDoctor's Note
This is the first of a five-part video series on B12, similar to my series on vitamin D, where I delved into the derivation of my recommendations, found for B12 in Vitamin B12: how much, how often? and in general in Optimum Nutrition Recommendations. For more context, check out Vegan B12 Deficiency: Putting It into Perspective and The Safest Source of B12.
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