Activated vitamins are vitamins in their most active form, meaning that they are more bioavailable for immediate absorption into your system. When vitamins are taken in their inactive form, they have to be activated by the liver and/or kidneys before the body can absorb and utilize them. (1) Consuming the active form essentially skips this step, particularly important for anyone with liver or kidney issues, but also in the case of a multitude of other conditions requiring more immediate bioavailability. (1)


Table 1 - Vitamins and their active forms (2)

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Some Comparisons Between Inactive and Active Vitamin Supplements

Vitamin B6 versus Pyridoxal 5’ Phosphate (P5P)

Vitamin B6 is naturally occurring in many fruits, vegetables and grains in the less bioavailable glycosylated form. (3) In order to get the most out of this less bioavailable version, the liver must first convert it to P5P, which is the most biologically active form of vitamin B6. (4) This active form, P5P, acts as a cofactor for more than 150 enzymes in the body, particularly in protein metabolism, and transsulfuration and decarboxylation reactions. (3, 5)

Full liver and intestinal function is necessary to successfully convert vitamin B6 to its active form, P5P. In circumstances where there may be problems with the conversion from inactive vitamin B6 to P5P, for example, where there is reduced liver function, it can be beneficial to supplement directly with P5P (active form) to ensure maximum absorption. (7) 

Folic acid and Active Folate's

Folate deficiency is associated with an increase in neural tube defects, cardiovascular disease, and cognitive dysfunction. (8) There are three common forms of folate supplementation; folic acid, folinic acid or 5-methyltetrahydrofolate (5-MTHF), with the two latter forms being the active versions. 

Cobalamin (Vitamin B12) versus Methylcobalamin (active form)

Similarly to the other examples, some studies have shown that using the active form of vitamin B12, methylcobalamin (MeCbl), is superior for its bioavailability and safety. (1) It has been shown that using cobalamin (CNCbl) results in reduced tissue retention of active vitamin B12, and that this may pose problems for those with particular nucleotide polymorphisms affecting their vitamin B12 metabolic pathways. (1) There are also concerns amongst researchers that long-term supplementation with CNCbl may result in a build-up of cyanide in human tissues. (1) For this reason, although MeCbl is typically more expensive, it is considered a superior form to CNCbl.

In conclusion, although many people may achieve adequate levels of individual vitamins through their diet or with the inactive versions of vitamin supplements, it is worth assessing vitamin status to ensure deficiencies are not overlooked. In the case of large deficiencies, certain genetic mutations, intestinal malabsorption, diabetes, or celiac disease, supplementation with the active forms may help to overcome difficulties in absorption and utilisation. 



1. Paul C, Brady DM. Comparative Bioavailability and Utilization of Particular Forms of B(12) Supplements With Potential to Mitigate B(12)-related Genetic Polymorphisms. Integr Med (Encinitas). 2017;16(1):42-9.

2. Amboss. Vitamins. 2020. Available from: 

3.  National Institutes of Health. Vitamin B6 Fact Sheet for Health Professionals [Internet]. 2020 [cited July 16 2020]. Available from:

4. Said HM. Intestinal absorption of water-soluble vitamins in health and disease. Biochem J. 2011;437(3):357-72.

5. Paiardini A, Giardina G, Rossignoli G, et al. New insights emerging from recent investigations on human group II pyridoxal 5’-phosphate decarboxylases. Curr Med Chem. 2017;24(3):226-44. 

6. Ueland PM, McCann A, Midttun O, et al. Inflammation, vitamin B6 and related pathways. Mol Aspects Med 2017;53:10-27.

7. Labadarios D, Rossouw JE, McConnell JB, et al. Vitamin B6 deficiency in chronic liver disease--evidence for increased degradation of pyridoxal-5’-phosphate. Gut 1977;18(1):23-27.

8. Scaglione F, Panzavolta G. Folate, folic acid and 5-methyltetrahydrofolate are not the same thing. Xenobiotica. 2014;44(5):480-488. doi:10.3109/00498254.2013.845705

9. Servy EJ, Jacquesson-Fournols L, Cohen M, Menezo YJR. MTHFR isoform carriers. 5-MTHF (5-methyl tetrahydrofolate) vs folic acid: a key to pregnancy outcome: a case series. Journal of Assisted Reproduction and Genetics. 2018;35(8):1431-5.


Written By Brittany Darling



Brittany Darling