Vitamin B12 Supplements in Ireland: Tablets, Lozenges and B-Complex Compared

A plain-English, evidence-based guide to vitamin B12 supplements in Ireland: what B12 is, the difference between methylcobalamin and cyanocobalamin, food sources, how much you need, the eight authorised EU health claims, and how standalone B12 compares with a full B-complex.

Vitamin B12 (cobalamin) definition: Vitamin B12 is a water-soluble, cobalt-containing B vitamin that the body cannot make itself and must obtain from the diet, occurring naturally almost exclusively in animal-source foods such as meat, fish, eggs and dairy.

What vitamin B12 is and what it does

Vitamin B12, or cobalamin, is the largest and most structurally complex of the vitamins, built around a central cobalt atom. It is water-soluble, which means the body does not store large circulating amounts in the way it stores fat-soluble vitamins, although the liver does hold a reserve.

B12 acts as a cofactor for two enzymes. One is methionine synthase, central to methylation and the recycling of homocysteine. The other is methylmalonyl-CoA mutase, involved in energy metabolism. Through these roles, B12 is needed for normal red blood cell formation, normal nervous system function and DNA synthesis.^[2]

Because humans cannot synthesise B12, it has to come from the diet or supplements. In the food chain it is produced by bacteria, which is why it concentrates in animal tissues and is largely absent from plants.

Vitamin B12 was first isolated in 1948, by researchers working independently in the United States and the United Kingdom, during research into pernicious anaemia. It was the last of the classical vitamins to be identified.

Methylcobalamin vs cyanocobalamin

Supplements use vitamin B12 in different chemical forms. The two most common are methylcobalamin and cyanocobalamin. This is one of the most searched B12 questions, so it is worth stating plainly and without marketing spin.

Methylcobalamin is a coenzyme form of B12, meaning it is one of the forms the body uses directly. Cyanocobalamin is a synthetic, very stable form that the body converts into active forms after it is absorbed.

You will see strong claims online that methylcobalamin is "better absorbed" or "more bioavailable." The honest position is that the comparative human evidence is mixed, and EFSA treats the authorised forms of B12 as sources of the vitamin without ranking one as superior. Both are legitimate, widely used forms. Choose on preference, label transparency and price rather than on a bioavailability claim that the evidence does not settle.

On the products in this guide: NOW Methyl B-12 lozenges and Doctor's Best Fully Active B Complex use methylcobalamin, while NOW B-100 Complex uses cyanocobalamin.

Tablets, lozenges, sprays and injections

Oral vitamin B12 comes in several formats, and the differences are mostly about preference and convenience rather than a clear effectiveness gap.

Tablets and capsules

The most common format. Swallowed with water, once daily. B-complex products are typically capsules or tablets. "Vitamin B12 tablet" is the single most-searched B12 supplement term in Ireland, and a standard swallowed tablet is a perfectly reasonable choice.

Lozenges and sublingual

Lozenges dissolve in the mouth. Many people prefer them because they are easy to take without water and pleasant to use. Sublingual and dissolvable formats are marketed on the idea of absorption through the mouth, although the evidence does not clearly establish that any one oral format raises B12 status better than another in the general population.

Sprays and liquids

Oral sprays and liquid drops are another convenient format, often chosen for children or anyone who dislikes pills. Again, format is largely a convenience decision.

Injections

B12 injections are a medical route, used in specific clinical situations such as confirmed deficiency with absorption problems, and are given by healthcare professionals. They are not an over-the-counter food supplement and are outside the scope of this guide. If you are dealing with a diagnosed deficiency, follow the advice of your GP rather than self-managing with oral supplements.

Food sources of vitamin B12

Vitamin B12 is found naturally almost only in animal-source foods. The richest sources are meat, fish and shellfish, eggs, and dairy products including milk and cheese. So yes, cheese and milk do contain vitamin B12, in modest amounts.

Plant foods do not naturally contain reliable amounts of active B12. Some plant foods are described as containing B12-like compounds, but these are not dependable sources. This is the central reason B12 is the nutrient most associated with vegan and vegetarian diets.

For people who eat little or no animal food, the practical sources are fortified foods (such as some plant milks, yeast extracts and breakfast cereals with B12 added) and supplements. Relying on a varied diet alone does not solve B12 intake if that diet excludes animal foods.

Who tends to have low vitamin B12

Vitamin B12 status varies a lot across the population. Green et al., in the Nature Reviews Disease Primers overview of B12 deficiency, report that subclinical deficiency affects between 2.5% and 26% of the general population depending on how it is defined, and that clinical relevance in the milder range is still debated.^[2]

The groups most likely to have low B12 are:

Older adults. Deficiency becomes more common with age, often because of reduced stomach acid and absorption rather than low intake.

Vegans and vegetarians. Diets low in animal foods are the most predictable dietary cause of low B12, because reliable B12 is concentrated in animal products.

People with reduced absorption. This includes some people on long-term metformin or acid-lowering medication (PPIs and H2 blockers), which can lower B12 levels over time.^[5]

This is educational information, not a diagnosis. If you have ongoing symptoms you think could relate to B12, the right step is a GP, who can test and advise. The HSE provides guidance on B12 and on planning a balanced plant-based diet.

How low vitamin B12 is assessed

Diagnosing B12 deficiency is a job for a GP, not a supplement label. It is included here because it is one of the most common questions people have, and knowing the tests helps you have a more useful conversation with a clinician.

Assessment usually starts with a blood test. The markers a GP may use include:

Serum total B12. The standard first-line blood test. It measures total circulating B12, though it does not separate the active fraction.

Active B12 (holotranscobalamin). Measures the portion of B12 actually available to cells, and is sometimes used when a total B12 result is borderline.

Methylmalonic acid (MMA) and homocysteine. These rise when B12 is functionally low, so they are used as functional markers to help interpret an unclear result.

No supplement diagnoses deficiency, and a normal-looking diet does not rule it out. If you think your B12 could be low, the right step is a GP who can test and advise. This guide is educational and is not a substitute for that.

How much vitamin B12, and can you take too much

There are two EU reference figures worth knowing, and they are not the same thing.

The EFSA Adequate Intake for adults is 4 µg/day, set by the EFSA NDA Panel based on biomarkers of B12 status across several EU countries.^[1] The Nutrient Reference Value printed on supplement labels for "% NRV" is 2.5 µg, set under EU labelling rules.^[4] That is why a 1,000 µg supplement shows a very large percentage figure on the label — it is measured against the 2.5 µg labelling value.

Most B12 supplements contain far more than 2.5 or 4 µg. The reason is absorption. Uptake through intrinsic factor, the main active route, is saturable, so only a small amount of B12 is absorbed from any single dose by that pathway. A small further proportion of a large oral dose is absorbed by passive diffusion, independent of intrinsic factor, which is why high label amounts are used so that a useful quantity is actually taken up. A large number on the label is not a sign you are overdosing.

On safety: vitamin B12 is water-soluble and has a low potential for toxicity. The EFSA NDA Panel did not establish a tolerable upper intake level because no adverse effects were identified to base one on, and B12 was not found to be carcinogenic or genotoxic.^[1] Excess is largely not retained. That said, "no upper limit" is not a reason to take very high doses; in people with normal B12 status, more does not deliver more benefit.

What vitamin B12 contributes to (authorised EU claims)

Under Commission Regulation (EU) No 432/2012, a defined set of health claims is authorised for vitamin B12. These are the only health claims that may legally be made for B12 in the EU, and they must be stated in their authorised wording. For vitamin B12, the authorised claims are:^[3]

Note the careful wording: "contributes to," not "boosts" or "cures." These claims describe B12's role in normal physiological function. They are not statements that supplementing will increase energy or improve mood in someone whose B12 status is already normal.

Evidence at a glance

B12 vs B-complex: which to choose

This is the practical decision most buyers are actually trying to make. The simple version:

Choose standalone B12 if you specifically want to cover B12 and nothing else. This fits many vegans and vegetarians, who are usually fine on the other B vitamins from diet but short on B12 specifically.

Choose a B-complex if you want broad daily coverage of all eight B vitamins together. This suits people topping up general B-vitamin intake rather than targeting B12 alone.

Within B-complexes there is a second choice: standard forms (folic acid and cyanocobalamin, as in NOW B-100) versus active or methylated forms (methylfolate and methylcobalamin, as in Doctor's Best Fully Active). Active-form products are marketed for people who prefer the pre-converted forms; for most people both work, and the practical difference is smaller than the marketing suggests.

All four are food supplements, not medicines, and all are vegetarian/vegan-suitable. The right pick is about what you want to cover and your budget, not about one being a "better" product in a clinical sense.

From food to function

Vitamin B12 in Ireland

In Ireland, vitamin B12 and B-complex products are sold as food supplements, regulated by the FSAI (Food Safety Authority of Ireland) under food-supplement law, not as medicines. They are available freely without prescription. Any health claims made on packaging or marketing must use the authorised EU wording under Regulation (EU) No 432/2012.

Vitamin B12 injections are different. They are a medical treatment, not a food supplement, and are administered through the health service or a healthcare professional. The HSE is the relevant health authority for symptom-related questions and for diagnosis of deficiency.

On price and tax: Irish VAT on oral food supplements is the reduced rate of 13.5%. Probiotic.ie dispatches from Dublin with tracked next-day DPD delivery within Ireland, and is an authorised Irish retailer for NOW Foods, Swanson and Doctor's Best. For UK customers, the same range is available through the dedicated UK store.

Frequently asked questions

What is the difference between methylcobalamin and cyanocobalamin?

Methylcobalamin is a coenzyme form of vitamin B12 used in supplements; cyanocobalamin is a synthetic form that the body converts to active forms after absorption. Both are recognised forms of vitamin B12. The evidence on whether methylcobalamin is absorbed or retained better than cyanocobalamin is mixed, so neither can be described as clearly superior. NOW Methyl B-12 lozenges and Doctor's Best Fully Active B Complex use methylcobalamin; NOW B-100 Complex uses cyanocobalamin.

How much vitamin B12 do I need per day?

The EFSA NDA Panel (EFSA Journal, 2015;13(7):4150) set an Adequate Intake of 4 µg/day of vitamin B12 for adults. The Nutrient Reference Value used on EU supplement labels is 2.5 µg, set under Regulation (EU) No 1169/2011. Most B-complex and standalone B12 supplements provide far more than this because B12 is poorly absorbed at high single doses and the surplus is not retained.

Can you take too much vitamin B12?

Vitamin B12 is water-soluble and has a low potential for toxicity. The EFSA NDA Panel did not derive a tolerable upper intake level for vitamin B12 because no adverse effects were identified on which to base one, and it was not found to be carcinogenic or genotoxic. High oral doses are generally considered safe, but a higher dose does not provide extra benefit in people who already have normal B12 status.

What foods contain vitamin B12?

Vitamin B12 occurs almost exclusively in animal-source foods: meat, fish, eggs and dairy, including cheese and milk. Plant foods do not naturally contain reliable vitamin B12, which is why fortified foods (such as some plant milks and breakfast cereals) and supplements are the main reliable sources for vegans and vegetarians.

Who is most at risk of low vitamin B12?

According to Green et al. (Nature Reviews Disease Primers, 2017, PMID 28660890), subclinical vitamin B12 deficiency affects between 2.5% and 26% of the general population depending on the definition used. The groups at highest risk are older adults, people who eat little or no animal-source food (vegans and vegetarians), and people with reduced absorption. Persistent symptoms should be discussed with a GP rather than self-treated.

Should I take standalone vitamin B12 or a B-complex?

A standalone vitamin B12 supplement suits people who specifically want to top up B12, such as many vegans and vegetarians. A B-complex provides all eight B vitamins together and suits people who want broad daily B-vitamin coverage. The choice depends on diet and what you are trying to cover. Both are food supplements, not medicines.

Are vitamin B12 lozenges better than tablets?

Lozenges dissolve in the mouth and are a convenient format, particularly for people who prefer not to swallow capsules. Swallowed tablets and capsules are also effective. The evidence does not establish that any single oral format is reliably superior for raising B12 status in the general population, so format is largely a matter of preference. B12 injections are a medical route used in specific clinical situations and are administered by healthcare professionals.

What happens if I stop taking vitamin B12?

Vitamin B12 is stored in the liver, and in people with normal absorption these reserves can last a long time, so levels tend to fall gradually rather than suddenly when supplementation stops. There is no dependency or withdrawal effect. However, if the original reason for low B12 remains, such as a diet low in animal foods or reduced absorption, levels are likely to decline again over time. Anyone concerned about their B12 status should speak to a GP, who can test and advise.

What is vitamin B12 good for, according to authorised EU claims?

Under Commission Regulation (EU) No 432/2012, vitamin B12 contributes to normal energy-yielding metabolism, to the reduction of tiredness and fatigue, to normal functioning of the nervous system, to normal red blood cell formation, to normal psychological function, to the normal function of the immune system, to normal homocysteine metabolism, and has a role in the process of cell division. These are the only authorised health claims for vitamin B12 in the EU.

Is vitamin B12 legal to buy in Ireland?

Yes. Vitamin B12 supplements are legal to buy in Ireland and are regulated as food supplements under FSAI (Food Safety Authority of Ireland) guidelines, not as medicines. They are sold freely without prescription. Irish VAT on oral food supplements is the reduced rate of 13.5%.

Where can I buy vitamin B12 and B-complex supplements in Ireland?

Probiotic.ie stocks standalone vitamin B12 and a range of B-complex supplements including NOW B-100 Complex (€22.95), Swanson Daily B-Complex (€15.95) and Doctor's Best Fully Active B Complex (€20.45), with tracked next-day DPD delivery from Dublin within Ireland. Probiotic.ie is an authorised Irish retailer for NOW Foods, Swanson and Doctor's Best.