Both vegan and non-vegan diets may be deficient in B12, so don't assume you're ok unless you've had your bloods taken.
New vegans will get the inevitable questions such as, "Where do you get your protein?" and "What about iron?".
However, in my experience, many people from both sides still lack a sound understanding of the importance of vitamin B12.
What is vitamin B12?
Vitamin B12, (cobalamin) is one of the B group vitamins responsible for enabling the use of carbohydrates, fats and proteins in the body. It is also accepted that B group vitamins keep the liver, skin, eyes and hair healthy (1).
Additionally, B12 is required in the synthesis of DNA and RNA - the genetic blueprint for every cell in your body and works with B6 and B9 (folic acid) to control homocysteine, an amino acid that often shows elevated levels in those with heart disease. It is uncertain whether homocysteine is a marker or the underlying cause of heart disease (1).
Contrary to what many websites fail to elucidate - including, but not limited to the University of Maryland Medical Center, vitamin B12 undergoes biosynthesis in some bacteria. It is not made by animals, including humans. The only way factory farmed animals receive vitamin B12 is either from the soil particles they eat or from supplementation as is the recommended best practice in Australia which has typically cobalt-poor soils (2), preventing sufficient intake of soil originating B12.
Plant foods don't contain B12. Vegans MUST supplement.
(Non-vegan humans supplement, too. However, it is the animals that receive the B12 first and retain it in their tissues.)
When you're choosing which forms through which to obtain your B12, not all appear equal. I know this only complicates the issue but the best way through this problem is by asking,
"What does the literature tell us?"
There are FOUR variants that can be sold as B12. This video would be a good primer regarding the four types.
- Methylcobalamin
- Adenosylcobalamin
- Cyanocobalamin
- Hydroxycobalamin (also spelled hydroxocobalamin)
A Case for Cyanocobalamin
According to the literature, Gomollon et al. (2017) found successful results in reversing B12 deficiency in patients with Crohn's disease using an oral dose of cyanocobalamin. Crohn's sufferers often have impaired ability to uptake nutrients in the digestive tract - and this is exactly where B12 is absorbed. In fact, it is absorbed in the ileum in a highly specific receptor complex. If those with impaired digestive function are able to obtain B12 orally through supplementation, it would appear reasonable to expect those with normal functioning digestive tracts to do the same.
A case for Methylcobalamin, adenosylcobalamin and hydroxycobalamin as alternatives to cyanocobalamin
In contrast to the Gomollon et al. (2017) study, Paul and Brady (2017) discuss the use of the three natural forms of B12 (methylcobalamin, adenosylcobalamin and hydroxycobalamin) as well as the synthetic B12 compound mentioned above - cyanocobalamin.
Paul and Brady's paper is a review of the literature and evaluated articles published in German, English and French up until June 2016. It should be noted that this cut off date was before the publication date of Gomollon et al. (2017).
In summary, Paul and Brady (2017) conclude that the three natural forms of B12 should be preferred over cyanocobalamin citing 'superior bioavailability and safety'. From what I understand, safety is made in reference to the single atom of cyanide in the B12 molecule. Cyanide is toxic, however it occurs naturally and is present in cyanogenic foods as well as cigarette smoke. The human body is able to excrete cyanide through the primary mechanism in the liver by rhodanese to thiocyanate which is excreted in the urine. The secondary mechanism of expulsion occurs through binding to B12 - you guessed it - cyanocobalamin (3).
Which form should you take?
Paul and Brady (2017) discuss genetic polymorphisms in humans inferring a range of abilities to utilise the various forms of B12. These polymorphisms are thought to hinder the optimisation of B12 in the body to a certain extent. As a result, individuals may benefit from using multiple forms in a trial and error method with blood tests confirming.
Hayley and I currently supplement with cyanocobalamin in a spray form. If you just want a simple method that doesn't require regular blood tests alternate between taking methylcobalamin and cyanocobalamin.
Considering the almost negligible cost, supplementing with additional forms of B12 may be a sound preventative measure.
Disclaimer
This is not medical advice. Consult with your doctor if you're interested in more information.
References and Further Reading
The anaerobic biosynthesis of vitamin b12
Vitamin B12: Biosynthesis of the Corrin Ring
Vitamin B12 Sources and Bioavailability
Spurious Elevations of Vitamin B12 with Pernicious Anemia
Pernicious anemia: New insights from a gastroenterological point of view
Europe PMC: Vitamin B12 deficiency
Vitamin B12 absorption: Mammalian physiology and acquired and inherited disorders
American Journal of Lifestyle Medicine: Understanding Vitamin B12
Nutrition Reviews: How prevalent is vitamin B12 deficiency among vegetarians?
Farm Health Online: Cobalt Deficiency
Flock and Herd: A review of vitamin B12 supplementation in sheep
Vibrancy UK: The vitamin B12 Issue
All content is original.
Disclosure: This article was not a paid promotion and was not self-upvoted. Nor were there any affiliate links.
Thank you so much for your support on my Steemit Space. Please Upvote, Comment and Follow 
I do my best to engage with all thoughtful comments. This space absolutely invigorates me, so shoot me a comment.. even a critical one. I love fans and I love argumentative a-holes. I don’t discriminate.
I’m still looking for an artist to cover my work on my fantasy saga, Adventures in Elowyn Glade. Please make some noise if you’re interested.