Vitamin B12 Supplements


Vitamin B12 Supplements

Vitamin B12 Supplements: different doses and active ingredients. B12 injections or B12 pills? High dosage vitamin B12. What is the RDA of vitamin B12?


  • What does an ideal vitamin B12 supplement look like? Where should you be careful?
  • Which active ingredient is the best?
  • What is the correct dosage for a vitamin B12 supplement?
  • Which additives can be found? Are they vegan?
  • Pills, drops or capsules?

Vitamin B12 Supplements: a Wide Range

While a balanced diet can ensure a good intake of vitamin B12, those following a vegan diet or those suffering from absorption disorders, might find they need to supplement their diets to ensure their body’s are not lacking in B12.

At the moment there are a lot of different supplementary products on the market and it can be confusing when trying to make sense of them all, so it makes sense to do some research beforehand to make sure you buy the most appropriate product. This page aims to provide a comprehensive overview of vitamin B12 supplements and to convey the most important information to consider when selecting products.

Vitamin B12 Supplements Differentiated

The vitamin B12 supplements currently available mainly differ in the following four ways:

1. Active ingredient 
Vitamin B12 comes in several forms, each with different advantages and disadvantages that the body utilizes in different ways (see below). The most well known forms are: methylcobalamin, hydroxocobalamin, adenosylcobalamin and cyanocobalamin.

Consider: Opt for the naturally occurring forms hydroxocobalamin and methylcobalamin as much as possible here.

2. Dosage
The dosages of different supplements can differ greatly, varying from 10μg to 5000μg per dose – the equivalent of 3 times to 1600 times the daily recommended intake. Both doses are suitable in different circumstances (see below).

Consider: Neither very low, nor very high doses are really worthwhile in most cases. A good dosage for prevention and maintenance therapy lies in the range of 250-500 µg.

3. Administration form
Vitamin B12 is available in capsule, pilldrop, sirup, toothpaste, cream and injection form. Each differs slightly in its impact.

Consider: Capsules are the purest supplement. Injections are only really necessary for cases of severe deficiency.

4. Supplement composition
Vitamin B12 is available as part of a B12-complex or even a multivitamin complex or simply in its own. Supplements that state vitamin B12 as the only active ingredient often contain additives such as sweetener, artificial color or flavoring, which can in some circumstances adversely affect our health. We recommend products that don’t contain additives and that are known for their purity (see below).

Consider: If possible, select capsules as there are hardly any additives used in these. Always be sure to check the ingredients list carefully.

Summary: The Ideal B12 Supplement

  • Active Ingredient
    Oral – methylcobalamin and/or hydroxocobalamin
    Injection – hydroxocobalamin
  • Dosage:
    Oral (typical cases): 250-500 µg/day
    Injection: 1000-1500 µg/week
  • Form
    Capsules, in cases of swallowing difficulties drops or sprays
  • Composition
    As pure as possible, as natural as possible

The rest of the article will explore these points further and provide tips on choosing the correct supplement for the right scenario.

Different Active Ingredients in Vitamin B12 Supplements

Vitamin B12 is available in different forms in supplements. In each different form a second chemical component is bound to the actual chemical component. All good quality supplements will provide the information of which B12 form it contains. Cyanocobalamin, hydroxocobalamin, adenosylcobalamin (5-deoxyadenosylcobalamin) and methylcobalamin are the most commonly used forms.

‘the synthetic B12’
nono4average to poorNo specific effect
the depot B12
yesno3strong Detoxification of cyanide and NO
the B12 for DNA and nerves
yesyes0averageDNA, brain, nerves, blood, detox
the energy B12
yesyes0averageenergy, muscles, brain, DNA

B12 Supplements and Their Active Ingredients

The various differences between vitamin B12 active ingredients in supplements are outlined clearly in the table above. In order to better understand the differences, we will examine each individual B12 type in further detail below.


Cyanocobalamin is synthetically produced and is almost never found naturally. In the body it is broken down into cobalamin and the toxin cyanide (hydrogen cyanide/prussic acid). People can react badly to cyanide, sometimes with severe reactions, although the amount absorbed from vitamin B12 supplements is very small. As long as the renal function is working well then the cyanide will largely be excreted. Those with renal function problems should avoid cyanocobalamin in general. Smokers should also seek an alternative active ingredient, as they are already exposed to higher levels of cyanide.1

Cyanocobalamin is still commonly found on the market due to how easily it can be synthetically manufactured and its stability. Particularly in the US, it has been the most widely used vitamin B12 supplement and in most cases has shown good results. However, due to the aforementioned disadvantages of cyanocobalamin, it is identified increasingly less frequently as a good supplement option and has even been replaced by hydroxocobalamin in WHO recommendations. Some researchers have even asked that cyanocobalamin be taken of the market completely, because it is so inferior to the other available forms.2,3


Hydroxocobalamin is the form of vitamin B12 that is naturally produced by most bacteria. To be biologically usable in the body it must first be converted into methylcobalamin and adenosylcobalamin. Unlike cyanocobalamin, it has the advantages of producing no toxins, not being excreted so quickly, being more readily available for use in the body and due to its superior protein binding qualities can be stored better.

Today, hydroxocobalamin is accepted as the international standard active ingredient for use in vitamin B12 shots and is also recommended by WHO on its essential medicines list.4 Apart from being used as vitamin B12 for medicinal purposes, hydroxocobalamin can used for its detoxification qualities, as it binds to cyanide and nitride and can then be transported out of the body. Interestingly, this product is actually cyanocobalamin.

Methylcobalamin und Adenosylcobalamin

Methylcobalamin and adenosylcobalamin are active forms of vitamin B12 that can be directly utilized by the body. Both cyanocobalamin and hydroxocobalamin must be converted into coenzymes methylcobalamin or adenosylcobalamin before they are biologically available in the body. Methylcobalamin is therefore often referred to as the ‘bioidentical’ form of vitamin B12. Medicinally, methylcobalamin and adenosylcobalamin are advantageous because they are able to take immediate effect, apart from this advantage they are both stored well in the liver.

We consider methylcobalamin to be the best form of vitamin B12 due to its immediate effectivity and fortunately it is now becoming increasingly available on the market. In Germany, adenosylcobalamin is not approved in dietary supplements but is known to possess similarly good qualities.

Absorption from Vitamin B12 Supplements

Considering the RDA is around 3 µg, the dosage levels of many vitamin B12 supplements can appear at first to be overdosed. However, the body is not capable of absorbing all the vitamin B12 within the dose.

With oral supplements, the body can absorb around 1.5 µg per dose via the intrinsic factor, regardless of how high the overall dosage level is. A further 1% of the dose can be absorbed. So in order to cover the minimum RDA of 2.4 – 3 µg with one dosage, a minimum of 100 – 150 µg needs to be taken. Alternatively, three small doses can be taken if spread apart of the course of a day, in order to optimize the use of the intrinsic factor. Three small dosages of 5 µg would be a potential sensible dosage for covering the daily allowance.

In cases of malabsorption, often the intrinsic factor fails to absorb any of its optimal 1.5 µg and passive diffusion can be the only method of absorption. Here, around 300 µg would be the lower limit for a single dosage to cover the body’s daily requirement – in order to afford a buffer, 500 µg would be a sensible dosage level to select.

High dosage vitamin B12 of more than 1000 µg is worthwhile if the body’s B12 store is exhausted and severe deficiency symptoms are present, as it not only has to cover the body’s daily requirement, but also must refill the body’s depleted storage.

Vitamin B12 Doses for Tablets and Capsules

Below is a table detailing the approximate amounts of vitamin B12 that will be absorbed when taken orally (i.e. tablets and capsules) and further one off doses. The table indicates that dosages of 100 µg will sufficiently provide for the body’s daily needs. If absorption is impaired, however, then the 1.5 µg absorbed via intrinsic factor becomes redundant and the only relevant figure is that calculated for passive diffusion.


Vitamin B12 Supplements in Prevention and Treatment

The following is a description of which dosages should be used in different situations for prevention and treatment.

1. Vitamin B12 dosages to supplement intake with the diet

For cases where the diet does contain sources of vitamin B12, however not quite enough to meet daily requirements. Often the case for vegetarians and vegans who eat a healthy diet but do not get enough vitamin B12. When optimally absorbed, small doses such as these should be enough to ensure that there is no deficiency.

Oral supplements
(tablets and capsules)
Low dose 3-50 µg/day
Shot/injectionnot necessary

2. Vitamin B12 to cover the daily requirement

In order to meet the body’s daily B12 requirement it is often advised to take a dose much higher than the actual need (3μg), when taking oral supplements. If taking three doses spread throughout the day then absorption via intrinsic factor will be optimised, so a lower dosage may be administered.

With oral supplements the average dose used to meet the body’s daily needs is between 150-250 μg. This dose will usually provide enough B12 to meet average needs. An increased dose of 300-500 μg is recommended when the body’s need is higher, for example impaired absorption, stress or illness.

Oral supplement
(tablets and capsules)
3x 3-5µg/day oder
1x 150-250µg/day (normal requirement)
1x 500µg/day (increased requirement)
Shot/injectionHydroxocobalamin: 1000µg every 3-6 months
Cyanocobalamin: 100µg every 2-3 weeks oder 1000µg/month

3. Vitamin B12 dosages for medicinal purposes or with absorption disorders

To treat absorption disorders and certain diseases, as well as to replenish the body’s store of vitamin B12, a high dose of vitamin B12 may be administered.

If there is an existing absorption disorder – which is quite often the case if the gastrointestinal tract is inflamed – then high oral doses of vitamin B12 should be taken for as long as the problem persists (1000-2000 μg/day), because the body will only absorb a small fraction of this amount. Alongside taking the B12 supplement, the cause of the problem must also be identified so that it can be fixed.

With shots, the same dosage would be used as with a maintenance dose, because the process naturally bypasses an absorption issues.

For some illness and disease vitamin B12 in used alongside other treatments. A high dose will usually be used in these instances also.

4. Initial medicinal dose of vitamin B12

When a severe deficiency has been identified or after a long period of malnutrition then an intense initial dose may be administered, often for a few days, in order to replenish the body’s store quickly. In these scenarios hydroxocobalamin has been particularly effective.

Oral supplements
(tablets and capsules)
1000-2000 µg/day
Shot/injectionHydroxocobalamin: 4 weeks of 1000 µg/week or 1-3 weeks of 2x 1000 µg/week
Cyanocobalamin: 5-8 weeks of 2x 1000 µg/week

Vitamin B12 Supplements: Administration Forms

B12 supplements are available in many forms. Other than tablets there are capsules, powders, drops, sirup, toothpastes and in shot form.Vitamin B12 fortified foods could also be considered as a form of supplement, but these won’t be explored in this article.

Oral B12 supplements like tablets and capsules are absorbed in the intestine. This is the most frequently used supplement to meet daily requirements. Although poor absorption is often the cause of vitamin B12 deficiency, results have shown this form of supplement to be just as effective as an injection when the dosage is high enough (the reasons for this are explained further on).

Vitamin B12 Pills

Pills are the best known form of B12 supplement, which also includes dragees and similar forms. Lozenges are not included in this category, there is a separate section dedicated to these below.

Tablets do have one large disadvantage in that they often contain a number of additives to achieve the desired shape, colour and taste. Some additives are suspected to impede the absorption of B12 in optimal locations like the stomach and intestine.

Additionally, some consumerists have questioned the safety of such additives.

Vitamin B12 Capsules

It is far easier to manufacture B12 capsules that do not contain additives, as usually only cellulose is required. For this reason capsules are often take preference over tablets. Capsules are one of the purest and often highest quality forms of vitamin B12 supplement, which is why they are usually popular with health conscious people who want to avoid synthetic additives.

Vegans should check labels carefully as capsules can often contain gelatine and lactose.

Sublingual Administration of Vitamin B12: Lozenges, Drops and Sprays

Vitamin B12 is able to be absorbed sublingual via the oral mucosa, meaning lozenges, drops and sprays are a viable supplement option. Drops and sprays are readily dissolved which allows for easy absorption, but also means they are easily swallowed too. Lozenges remain in contact with the oral mucosa for a much longer period and the vitamin B12 is released more slowly, which may well be advantageous. The disadvantage to lozenges are that they often contain additives like sweeteners, colorings and flavorings, while drops and sprays are more often manufactured without out these extras.

It is still unclear just how advantageous sublingual absorption is compared to absorption of capsules and tablets via the stomach or intestine is, because there are not sufficient studies on the subject. However, what can be said is that sublingual absorption is at least as effective as its alternative, which is why drops, sprays and lozenges are suitable alternative to tablets and capsules. Sublingual supplementary B12 forms are particularly helpful for children and the elderly who might have more difficulty swallowing.

Vitamin B12 Shots

A weekly or monthly injection of around 1000 µg is usually administered to those suffering absorption problems. The active ingredients most commonly used for shots are either cyanocobalamin or hydroxocobalamin, there is currently no adenosylcobalamin injection form and methylcobalamin is rarely used.

When should vitamin B12 be administered in shot form? Mostly in cases where malabsorption comes into play, as absorption via the stomach and intestine can be bypassed, ensuring the vitamin is absorbed. Several recent studies have also shown that high doses of orally administered vitamin B12 (around 2000 µg/day) are particularly effective due to the 1% that will be absorbed via passive diffusion.5 Today highly dosed oral supplements are considered equal to the injection option6. Although a much higher quantity is required, the discomfort of a needle and inconvenience is visiting a doctor are both avoided.

On the other hand however, it can be difficult to take such large amounts of vitamin B12 orally, meaning the shot form may well be the best method to quickly replenish the body’s store. A 700 µg shot of hydroxocobalamin can circulate the body for a long period of time, the same would not be achieved through oral supplements. Some may prefer a needle with longer periods between administration to daily tablets or capsules.

Vitamin B12 Toothpaste

Vitamin B12 enriched toothpastes are fairly new on the market. In cooperation with the Vegetarierbund (Vegetarian Union – VEBU) the company Sante have developed a vitamin B12 toothpaste that has proven to be effective as a result of initial testing from the University of Magdeburg. The active ingredient is cyanocobalamin and the toothpaste contains 100µg of vitamin B12 per gram, which show allow for 3.6 µg to be absorbed when brushing twice a day (this covers the daily requirement). This has been developed for vegans in particular, who might be trying to obtain vitamin B12 from a few different sources to ensure they are getting what they need daily. Alone the toothpaste may not be sufficient, but in conjunction with other supplements and sources it may prove very useful.

Composition of Vitamin B12 Supplements

Ideally supplements only contain the active ingredient and a casing that is as neutral a substance as possible. We advise against choosing supplements that contain additives (particularly aspartame), they might make some supplements more palatable, but their other qualities are questionable. Dyes are also completely unnecessary and should be avoided. Quite often a whole range of additives are used and how they interact with vitamin B12 has either only partially been explored or not at all.

We believe a little research into the product and its manufacturer can usually indicate the purity of the supplement. Reputable providers tend to exclude sweeteners and other useless additives, which we consider preferable.

Vegans should always read the label and check that the supplements doesn’t contain any animal products like gelatin or lactose.

Vitamin B Complex

Vitamins belonging to group B are heavily dependant on each other. They complement and reinforce one another and together are involved in the production of various enzymes and allow for a number of metabolic processes to take place. All B vitamins should therefore be in good supply and an appropriate balance should be maintained.

With this in mind, a vitamin B complex is a sensible option, particularly containing a B12 and folic acid combination as these two are highly interdependent.

Multivitamin supplements are a controversial topic, as it is suspected that synthetically produced vitamins, which are often substituted, do not have the same effect as their natural models(7). As previously mentioned vitamin B12 comes in different forms, some of which are not necessarily natural and each works differently in the body. Naturally occurring B12 in foods is never found in its pure form, it is bound to other molecules and so is complemented by a number of other substances, such as minerals and trace elements. For this reason many nutritional experts claim is much better to get B12 from natural food sources as opposed to synthetically. If vitamins are artificially obtained that great care should be taken to make sure they are as biologically identical to their originals as possible.

The other B vitamins are far easier to obtain from foods than B12, as they are found in abundance in plant foods. For this reason it would make sense to obtain just vitamin B12 synthetically and to take other B vitamins from natural food sources. Many B vitamins are found in the following foods: wheat germ, yeast, nuts, rice, fruits, spinach, legumes and pulses.

Nevertheless, there are some very good B vitamin complexes and vitamin complexes available on the market.

Vitamin B12 Overdose

It is almost impossible to overdose on vitamin B12. If really large quantities are ingested the excess can simply be passed out with the urine. No toxic effect has been recorded and so no upper limit for intake has been set. An intake of up to 5000 µg/day is considered medically to be safe.

Long-term use of megadoses are suspected to be linked to liver and kidney damage, although medical examples of this are so far non-existent.

In the initial stages of vitamin B12 treatment metabolism may change and intake of other substances may need to be increased. A tingling sensation in the hands can be an indication of a folic acid deficiency. Iron and potassium intake may need to increase as new blood cells are formed.

Vitamin B12 is one of the safest vitamins that can be taken. Commercial supplements can be taken in the doses advised above. If more than the suggested is taken an overdose is not at risk.

What Should you be Aware of When Taking Vitamin B12 Supplements?

Generally speaking vitamin B12 supplements are extremely user friendly, as an overdose is basically impossible and they can be taken any time throughout the day with or without food.

Having said this, a number of different substances and medicines can affect the absorption of vitamin B12. Listed below are a selection of these:

  • Alcohol
  • Nicotine
  • High doses of vitamin C
  • Aspirin
  • Antibiotics
  • Contraceptive pill
  • Proton-pump inhibitors (PPIs)
  • Chemotherapy
  • Psychotropic drugs
  • Medication for diabetes (metformin)
  • Medication for high blood pressure (ACE)
  • Medication for cardiac arrythmia
    (betablockers, nitrate sprays, nitroglycerin)
  • Cholesterol lowering medication (statin)
  • Zidovudine
  • Colchicine
  • Nitrite

If the above are also being consumed then you should consult your doctor to see how the B12 supplement can be optimized.


1Koyama K, Yoshida A, Takeda A, Morozumi K, Fujinami T, Tanaka N. Abnormal cyanide metabolism in uraemic patients. Nephrol Dial Transplant. 1997 Aug;12(8):1622-8.
2Freeman AG. Cyanocobalamin—a case for withdrawal: discussion paper. J R Soc Med 1992; 85: 686-771. PubMed
3Hans C. Andersson, Emmanuel Shapira, Biochemical and clinical response to hydroxocobalamin versus cyanocobalamin treatment in patients with methylmalonic acidemia and homocystinuria (cblC), The Journal of Pediatrics, Volume 132, Issue 1, January 1998, Pages 121-124, ISSN 0022-3476,
4WHO Model List of Essential Medicines, 18th list (April 2013)
5Lane LA, Rojas-Fernandez C. Ann Pharmacother Treatment of vitamin b(12)-deficiency anemia: oral versus parenteral therapy. . 2002 Jul-Aug; 36(7-8):1268-72.
6Andrès E, Dali-Youcef N, Vogel T, Serraj K, Zimmer J. Oral cobalamin (vitamin B(12)) treatment. An update. Int J Lab Hematol. 2009 Feb; 31(1):1-8. Epub 2008 Nov 19.
7Thiel R.J., Natural Vitamins May Be Superior to Synthetic Ones. Medical Hypotheses, 2000; 55(6):461-469

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