Everything you need to know about vitamin B12

Vitamin B12 and your body

Vitamin B12 is required for the normal function of the brain and nervous system, the formation of red blood cells, the metabolism of every cell of the human body, and much more.

B12-deficiency is linked to paralysis, psychosis, fatigue, depression, poor memory, blindness, breathlessness, and headaches[1][2].

Natural sources

The only natural source of vitamin B12 are some bacteria which live in the soil and water. In earlier times humans were able to obtain enough such bacteria from the drinking water and from not so well washed fruits and vegetables, but in today’s over-sterilized world this is nearly impossible.

Some foods are artificially fortified with B12. Examples include energy drinks, cereals, soy products, energy bars, nutritional yeast.

Grazing animals collect B12 from the soil at the roots of the plants they eat. Regurgitating animals (cattle, goat, sheep, deer) absorb B12 produced by bacteria in their guts. For meat-eaters, the meat and especially livers of such animals are a rich source of vitamin B12. Also mollusks and clams are quite rich in B12.

Note that while eggs, milk and cheese do contain vitamin B12, the amounts are relatively low. For this reason, people on a vegetarian diet should also take a B12 supplement.

Vitamin B12 supplementation

Warning: Since there are no plant sources of vitamin B12, taking a B12 supplement is crucial for anyone eating plant-based.

People who have switched to a vegan diet in their adulthood usually have enough B12 stored in their bodies for a couple of years.[3] However babies of vegetarian or plant-based mothers must receive a B12 supplement from birth on.[4]

Supplement amounts

The Recommended Dietary Allowance (RDA) vary slightly by country. They also vary by age, from 0.5 microgram (µg or mcg) for newborns to 1.2 µg for children and 2.4–3 µg for adults. Pregnant and breast-feeding women need up to 2.6–4 µg daily. However, our bodies are so bad at absorbing B12 supplements[5], that the recommended supplement amount is much higher: 250 µg daily or 2500 µg weekly.

The absorption of vitamin B12 becomes even less efficient around age 60, so the recommended supplement amount increases to 1000 µg daily[6].

There are two main ways of taking the supplements:

  • a pill is taken with a large glass of water (since this vitamin is water-soluble)
  • a slowly-dissolving pill is placed under the tongue. Despite manufacturer claims, there is no evidence that this method is superior[7].

Methylcobalamin or cyanocobalamin?

B12 supplements come in two different forms: methylcobalamin or cyanocobalamin. Methylcobalamin is more expensive, but is immediately bioavailable. Cyanocobalamin is cheaper, but the body must break it up and convert it to methylcobalamin, before it can absorb it.

B12 supplements are safe (they have been prescribed to pregnant women for decades), effective (people on a vegan diet have been supplementing for decades also), and available without a prescription. A year’s supply costs 15–30 EUR.

If you take too much B12 supplement, probably nothing bad will happen.[8] You will simply produce expensive urine.[9]

Are you deficient in vitamin B12?

There are three main tests for Vitamin B12[10]:

  • Vitamin B12 in blood serum, 15 EUR: tests the total B12 levels in your blood. It sounds like this should be the perfect test, but it’s not. B12 is not directly usable by your body, so this test measures how much B12 “is floating around in your system, but now how much was absorbed.” This test can reliably recognize only severe deficiencies, and it’s recommended.
  • HoloTC blood test, 15 EUR: tests for bio-available B12. Best for detecting the initial stage of B12 undersupply. If the value is as expected, you are fine. But if the value is too low, you don’t know how minor or severe the deficiency is.
  • MMA urine test, 45 EUR: Very sensitive and most reliable for detecting actual cellular deficiency. Can be carried out at home.

Is a plant-based diet really healthy?

Some traditional sources insist that a vegan diet is unhealthy, even dangerous. Without B12 supplementation, this is indeed true. So let’s clarify this once and for all:

Whenever anyone talks about a vegan or a plant-based diet being very healthy, they always mean a vegan or a plant-based diet supplemented with vitamin B12. If done right, a plant-based diet is the healthiest one possible.

Information sources:

  1. Oregon State University, Linus Pauling Institute, Micronutrient Information Center, "Vitamin B12"
  2. Office of Dietary Supplements, National Institutes of Health, "Vitamin B12 / Fact Sheet for Health Professionals"
  3. Madry, Lisowska, Grabowiec, Walkowiak, "The impact of vegan diet on B-12 status in healthy omnivores: five-year prospective study" Acta Sci Pol Technol Aliment , 2012; 11(2): 209–13
  4. Roschitz B, Plecko B, Huemer M, Biebl A, Foerster H, Sperl W, "Nutritional Infantile vitamin B12 deficiency: pathobiochemical considerations in seven patients" , Archives of Disease in Childhood. Fetal and Neonatal Edition, 2005; 90(3):F281-2
  5. Carmel R., "How I treat cobalamin (vitamin B12) deficiency." Blood 2008;112:2214-21
  6. Eussen SJ, de Groot LC, Clarke R, et al, "Oral cyanocobalamin supplementation in older people with vitamin B12 deficiency: a dosefinding trial" Archives of Internal Medicine 2005;165( 10): 1167– 72
  7. Amir Sharabi, Eytan Cohen, Jaqueline Sulkes, Moshe Garty, "Replacement therapy for vitamin B12 deficiency: comparison between the sublingual and oral route" , British Journal of Clinical Pharmacology, Volume 56, Issue 6, December 2003, Pages: 585-706
  8. "Dietary Reference Intakes: Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline1" , Institute of Medicine. Food and Nutrition Board, 1998
  9. Michael Greger M.D., "How Not to Die: Discover the Foods Scientifically Proven to Prevent and Reverse Disease"
  10. http://www.b12-vitamin.com "Vitamin B12 Deficiency Tests"

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