
What is the Best Form of B12 for You?
Best way to take B12 for optimal absorption – pill, shot, sublingual?
It’s a well-known fact that B12 does not absorb well. Only approximately 1-4% gets absorbed via the gut, so taking B12 sublingually is the best absorption avenue (holding it under the tongue or between the gums and cheek is most common). Consider some form of liquid or tablet/lozenge that can be sucked on or dissolved in the mouth. Holding the B12 in your mouth for as long as possible is best for maximizing absorption through the sublingual route.
Best tests to determine B12 deficiency & need
- Methylmalonic Acid (MMA)
- Homocysteine
- Active B12 (Holotranscobalamin - holoTC)
If both the MMA and Homocysteine test results are high, then you may not be getting enough B12 intracellularly (even if your blood serum tests show B12 as high)
Unfortunately most medical professionals test for B12 sufficiency using a blood serum test. However a blood serum test merely indicates how much B12 is swimming around in the bloodstream, NOT what is actually getting into the cells where it's needed for use by the body. B12 must be transported and absorbed intracellularly - only there does it benefit health and kick off important downstream processes. So knowing what's in the bloodstream is only indicating how much B12 has not been absorbed or used by the body yet. Blood serum tests assume if B12 is in the bloodstream, then your body can absorb it, but that's not the case with so many regarding B12.
B12 is much more complicated, it requires specialized transportation as well as multiple conversion steps. Many people have genetic mutations or health conditions which can disrupt these processes, making it difficult for the body to utilize B12 effectively. To get a clearer picture of your true B12 status (meaning whether B12 is getting to its needed places and if you have enough of it), testing B12 levels in the spinal fluid would be most accurate. But this test is rarely performed in clinical settings.
If you are low in B12, consider one or all 3 of the active B12 forms to ensure your cells have access to the most bioidentical forms available (hydroxocobalamin, adenosylcobalamin, methylcobalamin). DO NOT TAKE CYANOCOBALAMIN!!
There appears to be a general lack of education available to most healthcare professionals regarding the different forms of B12, how each type is processed in the body, as well as its specific benefits. Additionally, many are unaware of how certain genes or genetic mutations can influence which form of B12 might be most effective for an individual. So do your homework when it comes to B12 to determine which form may be best tolerated and most beneficial for you.
The most widely available form of B12 is cyanocobalamin, but it is not very active or beneficial to the body. Its absorption rate is relatively low, and contains some cyanide which the body must process. Cyanocobalamin is inexpensive, which is why it is commonly found in multivitamins and fortified foods. However, it is not readily absorbed because the body needs to go through several conversion steps before it becomes usable. Cyanocobalamin must first get converted into hydroxocobalamin before the body can actually use it. Hydroxocobalamin can be further converted into the active forms, adenosylcobalamin and methylcobalamin for cellular uptake. If someone has certain genetic mutations, these conversion processes may not function efficiently, making it difficult for cells to absorb and use vitamin B12 effectively.
Research shows that taking B12 in a sublingual oral form is more effective
for treating B12 deficiencies than actually getting B12 intramuscular shots (and it's usually much more convenient and affordable as well).1
NOTE: Different manufacturers use different terms for tablets that are meant to dissolve sublingually in the mouth, but “sublingual” is considered a pharmaceutical term by the FDA, so dietary supplements are not allowed to 'label' using that word. However, it doesn’t really matter what term you use (chewable tablet, lozenge, sublingual tablet, liquid, etc.) for maximum absorption the main idea is to hold the B12 in your mouth for as long as you can.
BE AWARE WITH SHOTS: Doctors typically give shots using cyanocobalamin, and many may not respond well to that form of B12 (especially when given at a high dose), you may have negative side effects. Try to find one of the 3 bioactive B12 forms.
What to do if you have high B12 blood results?
High B12 blood serum levels can often mean:
- The body is having trouble converting, transporting and absorbing vitamin B12 into the cells where it's needed for intracellular and downstream processes
- The vitamin B12 in your serum is inactive and not able to be utilized
- You could also have contributing deficiencies in iodine, selenium, molybdenum, and/or B21
- And it can also mean that you’re getting a form of B12 in your diet (or vitamins) that is not converting well in your body for absorption (likely cyanocobalamin)
Ironically, this is called a “paradoxical B12 deficiency”. And it can refer to a lack of iodine, selenium, and molybdenum which are the main reasons for not being able to activate B2. And B2 is highly correlated with B12 ... meaning if you are functionally deficient in B2, it is highly likely you will also have a B12 functional deficiency.2
A few suggestions below are based on opinions from Research Studies, Naturopathic Doctors and Nutritionists ... Methyl-Life®'s Non-Methylated Multivitamin product satisfies the top 3 suggestions below and our Methylated Multivitamin 3-product pack covers 4 of the 6.
How to supplement when B12 tests are high
I know my specific COMT & VDR Taq gene details. Display the best suggested B12 form(s) for me based on that information.
Are B12 intramuscular injections best?

4 forms of B12 explained
HYDROXOCOBALAMIN is a lesser-used bioactive form of B12 that is tolerated by many and understood to help the body promote neurotransmitters (for healthy brain function), protect against anemia (sometimes used for pernicious anemia), detoxify, manufacture myelin sheath, and much more. Hydroxocobalamin can also act as a scavenger of peroxynitrites that may build up in the body (particularly for those who may have COMT & other such mutations), converting the reactive oxidant back into methionine. This kind of "mopping up" activity can be beneficial for those dealing with headaches and/or migraines, inflammation, cold hands and feet, sore muscles and joints, fatigue, lack of motivation, memory challenges, feeling lightheaded when standing, brain fog, as well as symptoms of Chronic Fatigue and/or Fibromyalgia. Hydroxocobalamin also gets converted into methylcobalamin as well as adenosylcobalamin (or cobamamide) in the body - both are also bioidentical forms of B12 that can increase B12 sufficiency.
METHYLCOBALAMIN is probably the most well-known bioidentical form of B12 that is becoming much more available in vitamins and supplements. Methylcobalamin is known to promote methylation, reduce homocysteine, support brain & nerve health, and positively affect anemia as well as the circulatory & immune systems. While all forms of B12 are well-tolerated by many, methylcobalamin is the form of B12 that is most known for causing some mild side effects related to methylation. For some it can cause the heart to race or the body to become overstimulated, agitated or even anxious in some cases. Some may have trouble sleeping if they take it too late in the day, as it can overexcite the body via the methylation pathway.
ADENOSYLCOBALAMIN (also sometimes labeled as Cobamamide) is probably the most expensive and least-known bioidentical form of B12 to consumers. And while all forms of B12 are generally well-tolerated, clinically, doctors may find cobamamide to be the most well-tolerated of the three bioactive forms. Adenosylcobalamin helps in muscle recovery, myelin sheath repair, supporting mitochondria, and similarly to the other active forms, it also helps with anemia. According to research and clinical studies, B12 has a connection to Parkinson's and the adenosylcobalamin form particularly may be thought of as a valuable aid due to its action upon the muscles.
CYANOCOBALAMIN Cyanocobalamin is a synthetic form of vitamin B12 made in a lab. It is inactive, which means it must undergo a conversion process in the body before it can be absorbed and used. Cyanocobalamin is often used in supplements or prescribed by doctors as it is cheap to produce. It’s worth noting that the name "cyanocobalamin" refers to its cyanide molecule.1
Unlike bioavailable forms of B12 like methylcobalamin, cyanocobalamin occurs only in trace amounts in the body, usually from cigarette smoking or other sources of cyanide.2 When ingested, the body must break it down into its active form before it can be used, which may be difficult for people with SNPs (genetic mutations) on B12 metabolic pathways.3
The body excretes three times more cyanocobalamin in urine than methylcobalamin. This is because not all of the cyanocobalamin can be properly converted to the active form, and the leftover must be flushed out of the body.4 Researchers have expressed concern about cyanide accumulation in the body following long-term intake of cyanocobalamin from supplements and/or fortified foods.
Product Recommendations
Sublingual B12: well-tolerated, bioavailable Hydroxy B12 Tablets
$29.00
- Supports Healthy Red Blood Cells & Myelin
- Promotes Healthy Brain Function & Detoxification
- 3rd-Party Tested for Purity, Potency & Safety
- 90 Vegan, Non-GMO, Chewable Mint Tablets
Product Recommendations
Methylcobalamin B12 Complete - Vitamin B12 5000 mcg
$32.00
- All 3 Bioactive Forms of B12 for Full-Spectrum Absorption
- Methylcobalamin B12, Hydroxy B12 & Adenosylcobalamin
- 3rd-Party Tested for Purity, Potency & Safety
- 90 Vegan, Non-GMO, Chewable Mint Tablets
Product Recommendations
Methylated B12 3.75mg + L-Methylfolate 3mg as Methyl-Life®'s B-Methylated-II
$39.00
- Bioactive L-Methylfolate 3 Mg & Methylated B12
- Great for Bypassing MTHFR Mutations
- 3rd-Party Tested for Purity, Potency & Safety
- 90 Vegan, Non-GMO, Chewable Mint Tablets

Written By:
Jamie Hope - Founder of Methyl-Life
Medical Reviewer:
Kari Asadorian - Bachelor of Science in Nursing
Edited By:
Kari Asadorian - Bachelor of Science in NursingReferences
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Advait Vasavada, Preeti Patel, Devang K. Sanghavi; "Cyanocobalamin"; StatPearls [Internet]; 2024 Jan
https://www.ncbi.nlm.nih.gov/books/NBK555964/
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Cristiana Paul, David M Brady; "Comparative Bioavailability and Utilization of Particular Forms of B12 Supplements With Potential to Mitigate B12-related Genetic Polymorphisms"; Integrative medicine; 2017 Feb
https://pmc.ncbi.nlm.nih.gov/articles/PMC5312744/
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Cristiana Paul, David M Brady; "Comparative Bioavailability and Utilization of Particular Forms of B12 Supplements With Potential to Mitigate B12-related Genetic Polymorphisms"; Integrative medicine; 2017 Feb
https://pmc.ncbi.nlm.nih.gov/articles/PMC5312744/
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Cristiana Paul, David M Brady; "Comparative Bioavailability and Utilization of Particular Forms of B12 Supplements With Potential to Mitigate B12-related Genetic Polymorphisms"; Integrative medicine; 2017 Feb
https://pmc.ncbi.nlm.nih.gov/articles/PMC5312744/
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Merav Jacobson Bensky, Irit Ayalon-Dangur, Roi Ayalon-Dangur, Eviatar Naamany, Anat Gafter-Gvili, Gideon Koren, Shachaf Shiber; "Comparison of sublingual vs. intramuscular administration of vitamin B12 for the treatment of patients with vitamin B12 deficiency"; Drug delivery and translational research; 2019 Jun
https://pubmed.ncbi.nlm.nih.gov/30632091
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Gregory Russell-Jones, Mentor Pharmaceutical Consulting Pvt Ltd, Sydney, NSW, Australia; “Paradoxical Vitamin B12 Deficiency: Normal to Elevated Serum B12, With Metabolic Vitamin B12 Deficiency”; IOMC, Journal of Biology and Today’s World; ISSN - 2322-3308; 2022, Volume 11, Issue 3.
https://www.iomcworld.org/articles/paradoxical-vitamin-b12-deficiency-normal-to-elevated-serum-b12-with-metabolic-vitamin-b12-deficiency-91903.html
Table of Contents
Product Recommendations
Sublingual B12: well-tolerated, bioavailable Hydroxy B12 Tablets
$29.00
Methylcobalamin B12 Complete - Vitamin B12 5000 mcg
$32.00
Methylated B12 3.75mg + L-Methylfolate 3mg as Methyl-Life®'s B-Methylated-II
$39.00