Vitamin B12: Methylcobalamin Vs Cyanocobalamin

Vitamin B12: Methylcobalamin Vs Cyanocobalamin

Vitamin B12 is a water soluble vitamin essential in the human diet. There are 12 different types of B-Vitamin, some of which share function. Vitamin B12 exists in 4 forms but there is much debate about which of the 4 is most beneficial to human health.

These are:

  • Methylcobalamin. This the most bio-available form of Vitamin B12. It differentiates from the rest because it has Methyl- group (CH3).
  • Cyanocobalamin. This is the form most used in supplements because it’s the cheapest. It differentiates from the rest as it has a Cyano- group (CN), this is the artificial form.
  • Hydroxycobalamin. It differentiates from the rest because it has a Hydroxy- group (OH). This form is created by bacteria and is found in foods sources.
  • Adenosylcobalamin. It is also known as Coenzyme B12. This is the form used in the energy cycle and is not typically used in tablet form [1].

Vitamin B12 is not absorbed like most other vitamins, it requires another factor to help it bind. Firstly, it must be separated from its food compound. Vitamin B12 is unstable on its own so usually attaches to a protein. In the acidic stomach conditions these bonds break and release Vitamin B12. It then binds to a protein called Intrinsic factor (If) which is recognised by the cells of the small intestine and is absorbed into the blood stream[2].

Methylcobalamin vs Cyanocobalamin

There is crucial debate about which form of B12 to use in supplements. Many people are put off using Cyanocobalamin because it contains the precursor to Cyanide. However, Vitamin B12 is consumed in such small quantities(1-5mcg) that this would never be an issue. The body has no nutritional or chemical use for the Cyano- group, therefore any Cyanocobalamin consumed will be instantly converted to Methylcobalamin. Additionally, the Methyl- form is better absorbed by the body, it also maintains its function for longer in the biological system. This doesn’t mean to say one form should be favoured over the other, they are both excellent at providing nutritionally valuable quantities of Vitamin B12 to the body[3].

The History of Vitamin B12

In 1824 the first glimpses of B12 deficiency named ‘Pernicious Anaemia’ were found. Scientist Thomas Addison concluded that it was caused by a lack of stomach acid, and not a vitamin deficiency. In 1926 scientists Minot and Murphy worked off a study conducted by G.Whipple who fed liver to anaemic dogs only to find that their haemoglobin levels (a symptom of anaemia) were restored. Finally, in 1948 the chemical form was isolated, then in 1955 British scientist and chemistry expert D. Hodgkins discovered the complicated structure of the aforementioned Vitamin B12. Hodgkins’ discovery led to mass production of Vitamin B12 as a treatment for Pernicious Anaemia [4].

Deficiency and Symptoms

Deficiency is surprisingly common, even in the western world. Those most at risk of deficiency are Vegans, Vegetarians and the elderly. Deficiency is likely to occur in Vegans and Vegetarians because the only sources of B12 are animal derived sources. Deficiency can also occur due to inadequate absorption, such as with Inflammatory Bowel Disease, Celiac disease, or decreased stomach acidity, that is common in the elderly.

Symptoms of Vitamin B12 deficiency include the following:

  • Lethargy- tiredness and fatigue.
  • Lack of appetite
  • Pallor- Reduced haemoglobin leads to pale red blood causing the membranes of the eyes and lips to appear pale.
  • Feeling faint
  • Mouth Ulcers and Sore tongue. [5]

Why is B12 Important to health?

B12 and Energy Yield

According to the European Food Standards Agency (EFSA) B12 possesses the ability to promote energy yield, leading to reduced feelings of fatigue, improved neurological and psychological function. One study found an overall improvement in all areas, including mood and fatigue when Vitamin B12 was taken daily [6].

B12 and Cell Health

The EFSA also approved the claim that Vitamin B12 is responsible for healthy cell division and production of red blood cells. There has been a long associated link between Vitamin B12 and the symptoms of anaemia. Vitamin B12 deficiency has been clinically proven to cause macrocytosis, an enlargement of red blood cells. This is thought to be caused by incorrect cell division called dyplastic erythropoiesis which creates abnormally sized and misshapen cells. This abnormal shape causes them to lose their ability to carry oxygen inducing symptoms of anaemia[7].

B12 and the Immune System

Lastly, EFSA claims that adequate Vitamin B12 intake can promote a healthy immune system. One 2016 study found that in HIV patients the T-Immune cell CD4+ was highest after an administering a shot of Vitamin B12[8].

B12 and Cognition

There is strong evidence to suggest that Vitamin B12 can aid the longevity of our brains. A study by Morris et-al found that the combination of low B12 and high Folate (B9) levels led to impaired cognitive decline. Whereas high B12 and Folate levels were protective against cognitive decline [9].

B12 and Foetal Neural Tube Defects (NTDs)

Lastly, Vitamin B12 has strong correlation with the reduction of NTDs in unborn children. A recent study found that deficient mothers had a significantly increased risk for foetal NTDs compared to mothers with adequate B12. Pregnancy Vitamin B12 blood concentrations below 250 nanograms/litre were associated with the greatest risk[10].

What are the best ways to consume Vitamin B12?

The daily recommended intake for Vitamin B12 is 1.5mcg-2.0mcg/day. However supplements can pack a punch by containing as much as 300mcg without toxic effect.

As previously mentioned Vitamin B12 is only naturally found in animal products such as organ meats, oily fish, beef and dairy products. Many of these foods are not eaten due to ‘health scare’ or dislike Very few people consume dairy products and red meat due to claims of cancer and pesticide use. Additionally, fish and shellfish consumption in the UK is considerably below the worldwide average. Lastly, organ meats have gone out of fashion and are not favoured by the modern palate.

Therefore, a Vitamin B12 supplement is recommended to almost all people, and most certainly for Vegans, Vegetarians, the Elderly and people who suffer from bowel disorders. For those that consume some sources you are advised to take 1mcg of Vitamin B12. However for those who consume none of the food sources, you are advised to take 5mcg for optimal health.

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  1. Group.E. (205). Vitamin B12 Benefits: 4 Types and Their Health Benefits. Available:
  2. Axis. (2012). Vitamin B12 Absorption. Available:
  3. Coppard.S. (2013). Methylcobalamin vs Cyanocobalamin. Available:
  4. Betrinac. (2012). History of the Discovery of Vitamin B12. Available:
  5. Hicks.R. (2015). Vitamin B12 Deficiency. Available:
  6. Ellis.F, Nasser.S. (1973). A pilot study of vitamin B,, in the treatment of tiredness . Journal of Nutrition. 30 (2), Pg.277-283.
  7. Aslinia.F, et-al. (2006). Megaloblastic Anemia and Other Causes of Macrocytosis. Clinical Medical Research. 2 (3), Pg. 236-241.
  8. Adhikari.P, et-al. (2016). Effect of Vitamin B12 and folic acid supplementation on neuropsychiatric symptoms and immune response in HIV-positive patients.. Journal of Neurosciences in Rural Practice. 7 (3), Pg. 362-367.
  9. Morris.M, et-al. (2007). Folate and vitamin B-12 status in relation to anemia, macrocytosis, and cognitive impairment in older Americans in the age of folic acid fortification.. The American Journal of clinical nutrition . 85 (1), Pg.193-200.
  10. Molloy.A, et-al. (2009). Maternal vitamin B12 status and risk of neural tube defects in a population with high neural tube defect prevalence and no folic Acid fortification.. Pediatrics. 123 (3), Pg. 917-923.