In this article, we’re going to cover the difference between the total and active B12 test reference range and why you might be deficient even if your total B12 levels are in range.

What is vitamin B12?

Supplements are important for vegans

B12 is a water-soluble vitamin essential for the maintenance of blood, nerve, and DNA cells. (1)

B12 isn’t naturally found in any plant-based foods so those following a plant-based or vegan diet are often deficient. (2)

We’ve written a great blog article about the symptoms of vitamin B12 deficiency that you need to be aware of to catch it early.

We’ve also written blog articles about plant-based sources of B12 and different types of vitamin B12 supplementation.

? B12 is an essential vitamin that isn’t naturally found in plant-based foods.

What’s the difference between total and active B12?

B12 binds to two different proteins in your body; haptocorrin and transcobalamin.

B12 bound to haptocorrin cannot be utilized by your cells and is known as inactive B12. (3)

B12 bound to transcobalamin, however, can be utilized and helps keep your blood, nerves, and DNA cells healthy. (4,5)

Total B12 is the measure of BOTH active and inactive B12 in your body.

Active B12 is the measure of ONLY active B12.

? Active B12 is B12 that your body can use, inactive B12 is B12 that your body cannot use and total B12 is the measure of all B12 in your body.

What’s wrong with testing total B12?

The normal total B12 test reference range is between 200-1100 ng/L (nanograms per litre) and the normal active B12 test reference range is between 20-134 ng/L. (6)

So what’s the big problem?

Only testing for total B12 (as the NHS does) isn’t helpful as it doesn’t show how much active B12 you have.

You could be within a normal total B12 range but still be deficient if the majority of that B12 is inactive. (7)

To know how much B12 is actually being used you need to get your active B12 levels tested instead. (8,9)

? It’s important to test for active B12 instead of total.

Active B12 Test Reference Range: The Bottom Line

Are you dealing with symptoms of vitamin B12 deficiency even though your total B12 is within range? Get your active B12 levels tested!

We recommend a vegan blood test alongside our DNA test kit so you have all the information you need to meet your health goals.

References:

  1. https://pubmed.ncbi.nlm.nih.gov/28722952/
  2. https://pubmed.ncbi.nlm.nih.gov/23356638/
  3. https://pubmed.ncbi.nlm.nih.gov/17990953/
  4. https://pubmed.ncbi.nlm.nih.gov/27350907/
  5. https://pubmed.ncbi.nlm.nih.gov/16384893/
  6. https://pubmed.ncbi.nlm.nih.gov/19623286/
  7. https://pubmed.ncbi.nlm.nih.gov/32647416/
  8. https://pubmed.ncbi.nlm.nih.gov/22125690/
  9. https://pubmed.ncbi.nlm.nih.gov/16384886/