Sublingual B12

Sublingual B12 - Is it More Effective to Take it Under Your Tongue?

Vitamin B12 is a critical nutrient that helps with red blood cell and DNA synthesis and neurological function. Many people believe that the best vitamin B12 is sublingual but have a hard time holding it under their tongue.

We're often asked if our Why Not Natural liquid B12 will still be absorbed if it's taken orally, as many people prefer to stir it into their morning glass of water. The truth is that it depends on a number of factors, but it's likely you won't have any problem!

Keep reading to learn why you might want to supplement with B12, why taking it sublingually might be superior, and how to make sure you're maximizing the benefits.

Vitamin B12

This water-soluble nutrient is the most famous of the suite of 8 B vitamins known as the B Complex. It's found in animal products like meat and seafood, however, deficiencies are common even among meat-eaters.

Deficiencies become especially common with age as we produce less of a protein known as "intrinsic factor" that helps absorb B12. You can read more about signs of a B12 deficiency here.

Do You Need to Take B12 Sublingually?

The spot underneath your tongue (the mouth's mucous membrane) acts like a trap door, bypassing your stomach acid and the liver for direct absorption. Sublingual B12 (in either liquid or pill form) is designed to be held below the tongue for around 30 seconds for fast absorption.

It's often thought that this is a superior method, since digestive problems are strongly tied to B12 deficiency.

However, there's a difference between B12 taken in food and B12 in a carefully-designed supplement. A good supplement, like Why Not Natural B12 liquid, is purified and does not require stomach acid to break it down in order to be absorbed.

Many people who are over 50 or take certain medications (for example, acid blockers or proton pump inhibitors) produce very little stomach acid which puts them at high risk of a deficiency since they may not absorb it from their food, but they shouldn't have a problem absorbing a well-designed supplement.

So what about absorption: does taking B12 sublingually actually lead to a higher absorption rate? It depends on what you're comparing it with, and how much intrinsic factor your body produces.

Sublingual B12 vs B12 Injections

The largest study performed on patients with a B12 deficiency to compare the efficacy of intramuscular B12 injections vs. sublingual B12 supplementation was performed in 2019.. The study found that sublingual B12 was far more effective at reversing a deficiency than injections. (1)

Sublingual B12 vs Oral B12

One study using a mixture of B12 and B complex tablets divided a group of 30 subjects with a deficiency into two groups where one took the tablets sublingually, and one took them orally. Both groups experienced a correction of their deficiencies and there was no significant difference between those who took the supplement orally or sublingually! (2)

Good news for those who don't have the patience to hold B12 under their tongue! However, there are certain groups who won't get what they need from oral supplementation.

When Sublingual B12 is Necessary

There is one factor that makes taking your B12 supplement sublingually a must: having low intrinsic factor production. Intrinsic factor is a protein that helps with B12 absorption. (3)

If you suffer from pernicious anemia (characterized by lack of intrinsic factor production) you'll benefit from taking B12 sublingually. The autoantibodies of those who suffer from pernicious anemia attack the stomach cells that produce intrinsic factor. (4)

Risk factors of pernicious anemia (no intrinsic factor) include:

  • Being over 60 years of age
  • Northern European/Scandinavian ancestry
  • Autoimmune conditions such as Type 1 diabetes
  • Having had surgery to remove part or all of the stomach
  • Family history

You are also more likely to have low intrinsic factor production if you meet any of the following criteria:

  • Inflammation of the stomach lining, aka gastritis
  • Small intestine problems, such as celiac or Crohn's disease, or HIV
  • Chronic antacid usage
  • Infection of the gastrointestinal tract
  • Use of antibiotics (which can disrupt gut flora)

If you meet any of the above criteria, it's a good idea to hold your B12 sublingual below your tongue for 30 seconds before swallowing it. Even without intrinsic factor the body can still absorb about 1-2% through a process called passive diffusion, but it's important to supplement with a much higher dose than the recommended daily value when reversing a deficiency. (5)

Sublingual B12


So can you put your B12 liquid supplement in your drink? If you don't meet any of the risk factors above, go right ahead!  Your absorption rate will likely be the same either way.

If you think you might produce a low amount of intrinsic factor, it's best to stick to the sublingual method.

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(1) Comparison of sublingual vs. intramuscular administration of vitamin B12 for the treatment of patients with vitamin B12 deficiency

Merav Jacobson BenskyIrit Ayalon-DangurRoi Ayalon-DangurEviatar NaamanyAnat Gafter-GviliGideon KorenShachaf Shiber

(2) Replacement therapy for vitamin B12 deficiency: comparison between the sublingual and oral route

Amir Sharabi, Eytan Cohen, Jaqueline Sulkes, and Moshe Garty
(3) Vitamin B12 replacement therapy: how much is enough?
D T Watts
(4) Vitamin B12 Deficiency

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(5) How I treat cobalamin (vitamin B12) deficiency
Ralph Carmel
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