Vitamin B12 – Which method is better, Sublingual, tablet or Intramuscular?

Currently there is a lot of discussion regarding what Vitamin B12 is superior in improving optimum Vitamin B12 levels, whether that is tablet/oral form, spray/sublingual, or Intramuscular Injections.

I wish I could give you a definite answer, but I feel like the options I have are:

  1. Intramuscular
  2. Oral
  3. Sublingual
  4. Depends on your particular circumstances.

Firstly, it is not yet clear if sublingual Vitamin B12 is superior to encapsulated/tablet Vitamin B12, but studies suggest that high oral doses (1000 mcg to 2000mcg) of either may be as effective as intramuscular injections in improving Vitamin B12 to optimum levels.

I say may for a very particular reason. The only time in which oral doses are not effective in improving Vitamin B12 levels is when an individual has an issue with Vitamin B12 intake from the GI tract.

If you are experiencing these types of problems, the best is Intramuscular injections. This is because when Vitamin B12 is injected into the blood stream it completely bypasses any issues you may have from getting the Vitamin B12 from gut to blood.

So, for people with gut issues, Intramuscular injections is defiantly the way to go. Talk to your trusted GP and they can get that sorted for you. Obviously, this method is costlier, both money and time wise. But, to that I say, you can’t put a price tag on health.

The next discussion we need to have is regarding sublingual and tablet/capsule forms.

There are suggestions that the sublingual method of Vitamin B12 absorption is superior for 2 reasons:

  1. Part of the Vitamin B12 may be bound immediately to an R protein in the saliva and then carried down for further processing in the stomach.
  2. Absorption may start immediately in the mouth by diffusion.

Unfortunately, right now, we don’t know.

What we do know is:

  1. There is an R protein available in the saliva. R protein is a special protein that binds to Vitamin B12 to protect it from the high acidic levels that are experienced in the stomach. If the R protein did not bind to the Vitamin B12 the Vitamin breaks down and becomes unusable.
  2. This is the issue for me for Theory Number One: Vitamin B12 has one of the most complicated absorption processes out of all the vitamins and minerals. Because Vitamin B12 interacts with so many different binder proteins, each binder protein will act and have a stronger bond with Vitamin B12 depending on the acidity or basic levels within the body.
  3. R protein is also excreted from Parietal cells in the Stomach and binds to free Vitamin B12 at the high acidic levels experienced in the stomach, a pH of 1.5-3.5! This is quite different to the pH experienced in the saliva of the mouth at 6.2-7.6, which makes me doubt that the R protein of the saliva would bind immediately to the Vitamin B12 in the mouth.
  4. But until further studies are made available…

A study in 2006 which tested the sublingual/pill method concluded that there was no difference between the two methods.

But then another study conducted in 2017 involving Vegans and fortified Vitamin B12 toothpaste did show an improvement (although I think that the study design on this particular study was flawed).

So really, the jury is still out on which is better between these two methods and I shall leave the decision up to you.

I personally use the pill form. It is easy, I add it to my morning smoothie and I find it to be cheaper than sublingual options.

So, until next time!







Cochrane Reviews. Vidal-Alaball J, Butler C, Cannings-John R, Goringe A, Hood K, McCaddon A, McDowell I, Papaioannou A (2005). Oral Vitamin B12 versus intramuscular vitamin B12 for vitamin B12 deficiency. DOI: 10.1002/14651858.CD004655.pub2. Available from

Paul, C., & Brady, D. M. (2017). Comparative Bioavailability and Utilization of Particular Forms of B12 Supplements with Potential to Mitigate B12-related Genetic Polymorphisms. Integrative Medicine: A Clinician’s Journal, 19(1), 42-49.

Siebert, A., Obeid, R., Weder, S., Awward, H. Sputtek, A., Geisel, J, & Keller, M. (2017). Vitamin B-12-fortified toothpaste improves vitamin status in vegans: a 12-wk randomized placebo-controlled study. American Journal Clinical Nutrition, 105(3): 618-625. doi: 10.3945/ajcn.116.141978. Available from

Yazaki Y, Chow G, Mattie M. (2006) A single-center, double-blinded, randomized controlled study to evaluate the relative efficacy of sublingual and oral vitamin b-complex administration in reducing total serum homocysteine levels. Journal Of Alternative & Complementary Medicine, 12(9):881-885. Available from:



Essentials of Human Nutrition (4th ed.) (2012) by Jim Mann and Stewart Truswell.

Biochemistry: A short Course (2nd ed.) (2013) by John Tymoczko, Jeremy Berg and Lubert Stryer


One thought on “Vitamin B12 – Which method is better, Sublingual, tablet or Intramuscular?

Leave a Reply

Your email address will not be published. Required fields are marked *