The importance of vitamin B12 in your diet

During our 7-week vegan challenge, for one of my clinic subject I happened to do a report on the importance of vitamin B12.  It is one of the first vitamin that comes to mind when thinking about a vegan diet as this vitamin is mainly found in animal sources. I thought it could be a good idea to share my findings with you.

So here we go …

What is Vitamin B12? Why is it so important for your health?

Vitamin B12 in brief


  • Made by bacteria. Animals eat foods containing these bacteria resulting in the animals becoming sources of vitamin B12
  • Derived from animals only: Meat (liver), Fish, Shellfish, Eggs, Milk
  • Fortified foods: Soy, Milk, Cereals, nutritional yeast grown on B12 enriched medium
  • Non active & unavailable forms that can interfere with B12 metabolism and absorption:  fermented soy products (miso), Sea algae (spirulina)

Foods rich in vitamin B12

Preserve, Support or Increase B12 levels

  • Cooking method Oven or stovetop
  • Substance Calcium, R protein, Intrinsic factor (IF), Proteases
  • Drugs Choral hydrate

Destroy, Interfere or Decrease B12 levels

  • Cooking method Microwave
  • Substance Vitamin C, Iron
  • Drugs Alcohol, Aminoglycosides, Lithium, Aminosalicylic acid, Anticonvulsants, Colchine and Oral contraceptives

Healthy eating B12

Chief functions of vitamin B12

  • Make healthy red blood and nerve cells,
  • Helps synthesize DNA for new cell growth
  • Activates folate

Good levels of B12 are associated with good

  • Cardiovascular health
  • Cognitive functions
  • Stronger immune system
  • Energy levels and endurance.


None reported

Vitamin B12 in healthy ranges

  • It takes about 2 to 3 years to develop any sign of deficiency after lack of absorption in the body and 7 years to deplete B12 stores.
  • Vitamin B12 is stored in the liver
  • As most of vitamin B12 is reabsorbed, healthy people rarely develop a deficiency even with minimal intake.

AI Adequate intake

EAR Estimated Average Requirement

RDI Recommended Daily Intake

Recommendations B12''

What are the symptoms associated with deficiency of vitamin B12?

  • Pernicious anaemia Fatigue, Breathlessness, Poor resistance to infection
  • Nerve damage Numbness, Sore tongue, Tingling in the hands and feet, Paralysis
  • In infants Delayed growth and development, Movement disorders, Anaemia
  • Other signs and symptoms Constipation, Loss of appetite, Weight loss, Depression, Confusion, Dementia, Poor memory, Difficulty to keep balance, Folate deficiency, Large immature red blood cells, Lack of intrinsic factor or hydrochloric acid

Who is at risk of developing B12 deficiency?

  • Strict vegan over an extended period of time
  • Pregnant, lactating women who follow a strict vegetarian/vegan diet and their infants Vitamin B12 crosses the placenta during pregnancy and can be found in breast milk. Within months of birth, an infant can develop severe deficiency due to limited B12 reserves of the mother. If the deficiency is not treated, the neurological damage in the infant can be severe and permanent.
  • Patients suffering from malnutrition or malabsorptive conditions (such as IBD, Crohn’s disease or Atrophic Gastritis). These patients cannot absorb the vitamin B12 they are consuming. Normal function of the stomach, pancreas and small intestine is required for optimal absorption
  • Patients over 50 years old might also have decreased absorbing functions.

mcg = microgram

B12 recommendations

Are your B12 levels in a healthy range?

Ask your practitioner to test the following levels: Full Blood CountHomocysteine, Serum B12, MMA or Folate.

Investigations B12

What can you do to correct your B12 levels?

  • Adequate daily amount in diet Adults should include at least 3 good sources. Nutrients should preferably come from food sources.
  • Supplements Sublingual tablets, spray. Cyanocobalamin is the main form found in supplements as it is easily converted to methylcobalamin and 5-deoxyadenosyl, the active forms of vitamin B12 in the human body.
  • Injection Speak to your GP or health practitioner about this option.

B12 and Folate

Folate can mask B12 deficiency

Devastating neurological symptoms can occur if folate is prescribed instead of vitamin B12. Folate will help with the blood symptoms not the nerve ones.

There is so much more to say… So always read the labels and discuss your options with your health practitioner! 

Do you wish to read more healthy vegan articles? Click here then: How to be a healthy vegan?

vitamin B12 healthy eating


Lab Tests Online Australasia 2011, Vitamin B12 deficiency, viewed 15 May 2014,

Linus Pauling Institute 2007, Vitamin B12, viewed 16 March 2014,

Mądry, E, Lisowska, A, Grebowiec, P & Walkowiak, J 2012, ‘The impact of vegan diet on B-12 status in healthy omnivores: five-year prospective study’, ACTA Scientiarum Polonorum Technologia Alimentaria, vol. 11, no. 2, pp. 209-213, viewed 16 March 2014,

National Institute of Health – Office of Dietary supplements 2011, Vitamin B12 Dietary supplement fact sheet, viewed 16 March 2014,

NHMRC Nutrient References Values for Australia and New Zealand 2006, Vitamin B12, viewed 16 March 2014, 

Pagana, K & Pagana, T 2014, Mosby’s Manual of Diagnostic and Laboratory Tests, 5th edn, Elsevier, St Louis

Whitney, E, Rolfes, S, Cameron-Smith, D & Walsh, A 2011, Understanding Nutrition, Australia and New Zealand Edition, Cengage Learning, Melbourne.


4 thoughts on “The importance of vitamin B12 in your diet

  1. Super complet cet article! On entend souvent 2 idées différentes “les vegans n’ont besoin d’aucun complément même en B12” et son contraire.
    Je prends de la B12 dans un mix de vitamines chaque jour, du yeast enrichi, quelques produits au soja…


    • C’est difficile effectivement de s’y retrouver des fois. Je pars souvent du principe que le corps a besoin d’un peu de tout mais avec modération et qu’il est important d’écouter son corps. Perso, je ne suis pas une grande mangeuse de protéines animales mais je me suis rendue compte que je ‘fonctionnais’ moins bien en ne consommant que des protéines végétales. Si des signes et symptômes commencent à se manifester il faut alors regarder si le niveau de vitamine B12 est adéquat, bien absorbé ou s’il s’agit d’autre chose 😉


      • Et justement en regardant ton alimentaire végétalienne, il n’y a pas des ajustements pour que tu sentes aussi bien qu’en consommant des protéines animales?
        J’ai souvent des checks-up sanguins à faire pour un autre soucis et aucune carences depuis des années.
        Il faut écouter son corps avant tout, surtout si il exprime une carence…
        Comme tu dis, la modération est importante. “Balance is the key of life”! 🙂


      • Il y’a des nutriments que tu ne peux trouver que dans des produits d’origine animale. D’autres aliments peuvent aider bien entendu ainsi que les suppléments mais après il faut bien savoir ce qu’ils contiennent! Beaucoup de personnes fonctionnent très bien avec une alimentation végé. Si tu fais des check-ups réguliers et te sens bien au quotidien physiquement et mentalement alors no worries! L’important c’est de sentir si ça change!


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