Elements of Nutrition- Spotlight on B12

Spotlight on B12

Our resident naturopath and nutritionist, Buffy Ellen from Be Good Organics, tackles the important issue of B12 intake.

This issue we’re talking about all things B12. Vitamin B12 is one of the most important nutrients to consider when you’re embarking on a plant-based diet, as it’s quite hard to find naturally in plant-based foods.

This isn’t just a “vegan” issue however — B12 deficiency is relatively common amongst omnivores too, with between 8% and 39% of the overall population affected.

B12 is actually produced by bacteria, in combination with cobalt in the soil.  As much of our soils are now becoming depleted, even some livestock are now being supplemented with B12. In addition, our hyper-sterile food environment means that B12 is virtually non-existent in plant-foods, other than some tempeh, miso, mushrooms, and seaweed (and even then these have often not been tested, and therefore can’t be universally relied upon).

I therefore recommend getting your B12 from a combination of sources — from certain natural organic unsprayed whole foods, to fortified foods, then to supplements if your blood tests show you’re low. I recommend getting a full array of baseline blood tests done if you’re embarking on a plant-based diet, and then get them done again in 6 months time to see where your levels have moved. It’s the relative movement that’s most important, as opposed to just the absolute levels. 

If you’re a long-standing vegan eater, I’d do the same now — baseline bloods now, again in 6 months to make sure everything is stable / moving in the right direction, then annually once you’re in good range.

What is B12?

B12 is one of the most important nutrients for humans, as it’s needed for red blood cell formation and energy production, our nervous system (to synthesise myelin, the insulation around our nerves), and for DNA replication (to help our body grow and repair). There are four key forms:

  • Cyanocobalamin: Most common form found in supplements, fortified foods, and naturally occurring in foods. 
  • Hydroxocobalamin: Main storage form in the body, and a biological intermediate (converts from this form to the below).
  •  Adenosylcobalamin: Biologically active coenzyme form, used in the body’s reactions. 
  • Methylcobalamin: Also a biologically active coenzyme form. 

B12 is one of the water-soluble vitamins from the micronutrients group (those we need in small amounts). 

How much do you need per day?

Infants (less than one year)     0.4–0.5mcg

Children (1–8 years)    0.9–1.2mcg

Teenagers (9–18 years)   1.8–2.4mcg

Adults (19–50 years)  2.4mcg

Adults (more than 50 years)   more than 2.4mcg

When pregnant     2.6mcg

When breastfeeding    2.8mcg

Note: These figures are based on average intakes in the general population, as opposed to intakes required for optimal health. Higher intakes do not necessarily equate to better health outcomes. 

Symptoms of B12 deficiency

Short term: Fatigue, dizziness, muscle weakness, paleness, shortness of breath, and cognitive dysfunction.

Long term: Nervous system damage, numbness and tingling in the hands and feet, visual disturbances, memory loss, dementia, impaired vision, and infertility.

What can cause deficiency?

B12 deficiency is relatively common, especially in women, with anywhere between 8% and 39% of the population affected.


  1. Insufficient cobalt in the soil: Animals require cobalt to make B12, and with our modern farming practices, is increasingly deficient in our soils. Some livestock are now supplemented with B12 as a result. 
  2. Insufficient dietary intake: Not enough B12-containing foods, fortified foods, or raw foods (bear in mind B12 levels degrade during cooking and storage). 
  3. Malabsorption: Due to age, impaired gastric function, a lack of other nutrients/co-enzymes that help with absorption, deficiencies in iron/folic acid/vitamin E, co-consumption of high levels of vitamin C, drugs and alcohol, and animal sources (harder to cleave off the B12 from animal protein). 
  4. Greater requirements: During pregnancy and lactation, and if you’re trying to get pregnant; older age (deficiency more common >50 years due to reduced stomach acid); and athletes (greater cell turnover).
Can you find it naturally in food?

Some plant foods have been shown to contain substantial amounts of naturally occurring B12, thought to be due to exposure to bacteria, soil, or insect contamination. This has been proven by numerous studies: 

  • Korean centenarians: Plant-predominant but consume high levels of these foods — similar B12 levels to the general population. 
  • Pregnant women: B12 levels similar between vegans, vegetarians, pescatarians, and omnivores. 
  • Breastfeeding women: B12 levels in breast milk similar between omnivores, vegetarians, and vegans.
Things to watch out for
  • Inactive/analogue/pseudovitamin forms: A significant portion of natural B12 is this type and not as bioavailable. 
  • Levels: vary depending on soil / season /processing. 
How to Ensure Adequate Intake

Natural foods: Seaweeds (nori, karengo, chlorella, spirulina), mushrooms, tempeh, miso > Choose organic

Fortified foods: Plant milks, nutritional yeast > Many plant-based foods are now fortified, check the label

Supplements: Cyano, hydroxo, methyl-cobalamin > Hydroxocobalamin preferred, liposomal enhances absorption, methyl only if you’re an undermethylator

Injections: Last resort

Buffy is one of Australasia’s leading plant-based nutritionists and naturopaths and is also the founder of the New Zealand food blog, Be Good Organics. For more plant-based recipes, follow Buffy on Instagram and Facebook (@begoodorganics), or find her at begoodorganics.com.

Aotearoa Vegan and Plant Based Living Magazine
This article was sourced from the Spring 2021 edition of The Vegan Society magazine.
Order your own current copy in print or pdf or browse past editions.

The articles we present in our magazine and blog have been written by many authors and are are not necessarily the views and policies of the Vegan Society.

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