The B12 issue

  • Vitamin B12 is made by bacteria that live in soil and water, and are ingested by animals.
  • Deficiency causes serious consequences including anaemia, depression and elevated homocysteine.
  • Vegans, older people and those taking acid-suppressing medication should either take B12 supplements routinely or get a blood test for serum B12 every year.
  • Vitamin B12 injections are unnecessary; oral supplementation, especially with sublingual sprays or lozenges, is as effective, and possibly more effective, than injections.

However, vitamin B12 deficiency is very common in the general population; the Framingham Offspring Study found that, of the almost 3000 people tested, 39% had vitamin B12 levels below the desirable range. Interestingly, meat intake was not found to correlate with higher B12 levels in this study.

The prevalence of deficient or suboptimal B12 levels is highest in the elderly (very few of whom are vegetarian or vegan!!!), so it is clearly not a problem confined to those eating plant-based diets.

The fact is, vitamin B12 is made by bacteria – either living on the roots of plants, in the guts of animals or in water – and it only occurs in animal-derived foods as a product of bacterial activity.

If we drank water out of ponds, pulled vegetables out of the ground and ate them dirt and all, and generally weren’t so scrupulous with our food hygiene, we would all receive a perfectly adequate amount of vitamin B12 each day (along with a hefty dose of intestinal parasites, which our ancient ancestors were plagued with, and pathogenic bacteria). But chlorination of town water supplies kills B12-producing bacteria along with the nasty ones, and our vegies reach us in a scrubbed state, so we have very little exposure to these natural sources of B12.

Anyone adopting a plant-based diet should ask their GP for a serum B12 test every year unless they’re taking a supplement on a regular basis. Up until recently, the serum vitamin B12 test (which has a reference range so wide you can drive a Mack through it) was the only one you could get from most doctors unless you offered to sleep with them ;-). This resulted in many people with serum levels in the lower end of the reference range being reassured that their vitamin B12 level was ‘normal’, when in fact they were showing early signs of B12 deficiency such as increased red blood cell size.


Fortunately, recent changes to testing procedures mean that if your serum B12 is in the lower end of the reference range, your blood sample will automatically be tested for ‘active’ B12 (holotranscobalamin), which is a much more accurate indicator of your B12 status.

If you’re over 50, you should also have an annual B12 blood test regardless of your dietary practices, because our ability to absorb B12 declines with age due to a condition called ‘atrophic gastritis’, which reduces stomach acid production.

You should also get tested each year if you’re on acid-suppressing medications such as Nexium, Prilosec, Zantac or Tagamet, which increase the risk of B12 deficiency. Better yet, make the right changes to your diet and get off acid suppressing medication, which also increases the risk of Streptococcus pneumoniae-associated pneumonia, hip fracture and other non-fragility fractures and polyps in the stomach that can turn cancerous.

I’m often asked by my clients whether supplemental vitamin B12 is derived from animal products, and whether the supplements are ‘natural’.

Here are the facts: All B12 supplements are made by bacteria which are purpose-grown on a cobalt-enriched medium in a laboratory. The B12 produced from this process is just as natural as the bacterial B12 found in flesh, dairy and eggs – that is, it’s made in the same way (i.e. by bacteria), and has exactly the same chemical structure, as vitamin B12 that you would get by eating the flesh or eggs from an animal.

The best B12 supplement is a sublingual (under the tongue) spray or lozenge. The vitamin B12 in these preparations is absorbed through the mucous membranes under the tongue, by passive diffusion. This sublingual absorption bypasses the numerous biochemical processes that take place in the gastrointestinal tract, which is a huge advantage for people with impaired absorption due to advancing age or gastrointestinal problems.

Oral vitamin B12 supplements, in sufficient doses, have been shown to be just as effective as B12 injections, even for people suffering from pernicious anaemia (a condition in which secretion of intrinsic factor, which is necessary for B12 absorption in the gut, is impaired). So there’s no need for B12 injections, which can be painful, are potentially dangerous in patients who are taking anticoagulants such as warfarin, and require a visit to a doctor or nurse, which adds inconvenience and extra cost.

A dose of 500 mcg of B12 2-3 times per week is sufficient for most adults to maintain good levels of vitamin B12; children require proportionately less depending on body weight. If a blood test has established that you have a B12 deficiency, take 500 mcg daily for 2 months, then repeat the blood test.

Although the science is not 100% clear on this, I lean toward using a methylcobalamin spray rather than cyanocobalamin, as cyanocobalamin has to be converted into methylcobalamin in your body anyway in order to be used, and methylcobalamin may be better retained in the body once absorbed than cyanocobalamin. Methylcobalamin is available in Australia in injection or patch form, or you can order methylcobalamin sprays for personal use only (i.e not for retail sale) from overseas.

I get mine from iHerb, which has a huge range of products, and fast, cheap shipping. If you haven’t already set up an account with iHerb, you can do so in seconds flat, and then use the discount code UTE208 at checkout to get $5-10 off your first order.

Just one word of warning: high dose vitamin B12 supplements have been reported to cause or aggravate cystic acne. I recommend choosing a supplement that contains 500 mcg or less of vitamin B12 to minimise this risk.

The bottom line: ensure your B12 level is sitting pretty by using a B12 supplement, then relax and enjoy your yummy, healthy plant-based food. (Or eat dirt if you’d rather get intestinal parasites along with your B12…)