Guide
Always tired despite enough sleep? It could be vitamin B12 deficiency (2026)
Last updated: 31 July 2026
Written by
Health Tested Editorial Team
It could be vitamin B12 deficiency. But beware: most B12 supplements do not work.
Chronic exhaustion, difficulty concentrating and forgetfulness: what many people dismiss as normal stress is often an undiagnosed vitamin B12 deficiency.
Current estimates show that in Germany, up to one in five people are affected. Among people over 65, it's as many as one in three, and many of them have no clear diagnosis, because deficiencies often go undetected.
But here's the real problem: even if you're already taking B12, your body probably can't absorb it. With conventional tablets and capsules, 99% of the active ingredient is destroyed by stomach acid before it reaches the bloodstream.
The result: you take B12, but the symptoms persist. Tiredness, lack of energy, tingling in your hands and feet.
There is a solution, though: liposome technology, which increases vitamin B12 absorption many times over.
Top of our 2026 test: Melinava Vitamin B12
- Liposome technology: up to 64 times better absorption (more on this below)
- Bioactive methylcobalamin
- For energy and concentration
- Made in Germany | Vegan
- From 249 kr (when you buy three packs)
- Free delivery
- 30-day money-back guarantee
There are countless vitamin B12 supplements on the market, but not all of them are effective.
The problem with conventional B12 supplements
Vitamin B12 is an essential vitamin that your body can't produce itself. It normally comes from animal foods, but many people turn to food supplements instead.
The problem: most B12 supplements have very poor bioavailability.Three reasons why ordinary B12 tablets do not work
- Destroyed by stomach acid. Up to 99% of the active ingredient is destroyed by stomach acid before it even reaches the gut. That's the main reason why people still have signs of deficiency even though they take B12 every day.
- Limited intrinsic factor. Your body's natural B12 absorption is limited by a transport protein. In people over 50, and in people with gut problems or on medication, this mechanism often stops working properly.
- Inefficient passive absorption. Without intrinsic factor, only about 1–2% of the B12 you take can be absorbed passively. Even from a 1,000 µg tablet, only 10 µg reaches the bloodstream, and the rest is excreted unused.
The result
You take B12, but the symptoms persist: tiredness, poor concentration, tingling in your hands and feet. That's not because B12 doesn't work, but because it never reaches your bloodstream.
This is why conventional tablets often can't give your body enough of the vitamin.
A vitamin B12 deficiency can have serious consequences, especially for the immune system, the nervous system and the cardiovascular system.
What your body needs vitamin B12 for
Your body can't function without vitamin B12. Here's why this nutrient matters so much:
- forming red blood cells
- forming DNA and RNA (and so taking part in cell growth and cell division)
- getting folic acid into your cells
- breaking down various fatty acids
- keeping the nervous system working
- forming the protective sheath around nerve fibres
- your body's natural detoxification processes
- energy metabolism
Causes of vitamin B12 deficiency
A vitamin B12 deficiency can have a number of causes:
- chronic inflammation of the stomach or gut
- taking certain medicines (e.g. antibiotics, acid blockers and other acid-reducing medicines)
- regular alcohol consumption
- stress
- a poor diet
- an unhealthy lifestyle
- a vegan diet
- harmful environmental factors
- ageing (falling levels of intrinsic factor)
- certain underlying conditions (e.g. Crohn's disease)
Why gut problems make ordinary B12 supplements ineffective
'A healthy gut is the root of all health' (Hippocrates)
Even if B12 survives stomach acid, it faces a second hurdle: a weakened gut can't absorb it.
Those most affected include people:
- taking medicines (acid-reducing medicines, antibiotics)
- living with chronic stress or lack of sleep
- with gut problems (chronic inflammation)
- over the age of 50 (gut health naturally declines with age)
The problem is that ordinary tablets depend on a gut that works properly. If yours isn't working at its best, even the highest dose won't help.
Melinava solves this problem with liposome technology: the B12 is packed into tiny fat bubbles that bypass the gut and carry the active ingredient directly into the blood, whatever the state of your gut flora.Signs of vitamin B12 deficiency
If you're deficient, the following symptoms can occur:
- tiredness
- weakness and confusion
- anaemia
- headaches
- digestive problems
- hair loss
- nerve problems
- muscle weakness
- tingling in the arms and legs
- changes in sensation, even paralysis
- a burning tongue
Psychological symptoms can also occur:
- attention problems
- depressed mood
- mood swings
- nervousness and irritability
- neurological disorders
- poor concentration and memory
Intrinsic factor: why high-dose B12 does not help
Many B12 supplements come in extremely high doses (500–1,000 µg). Why? Because manufacturers know that only a fraction is absorbed.
The problem lies with intrinsic factor, a transport protein in the gut that severely limits B12 absorption.
Two absorption routes, both inefficient
The active route (with intrinsic factor):
- efficient, but limited to around 2 µg per dose
- often fails (age 50+, medicines, gut problems)
The passive route (without intrinsic factor):
- only around 1% of the dose is absorbed
- of 1,000 µg, only 10 µg reaches your blood
Liposomes solve this problem
Liposomal B12 bypasses both routes and carries the active ingredient directly through the gut wall into the blood, independently of intrinsic factor.
The result: up to 64 times better absorption with a lower dose.
⚠️ Important: not all 'drops' are liposomal. Look for genuine, laboratory-tested liposome technology.
Forms of vitamin B12: why they are not all equal
It's not only absorption that matters: the form of B12 also makes a huge difference. Most cheap supplements use the wrong form.
Cyanocobalamin: the cheap, synthetic form
Used in: most cheap B12 supplements
- synthetic, not natural
- your body has to convert it into active B12 first (which costs energy)
- lower bioavailability
- advantage for the manufacturer: cheap, with a long shelf life
- drawback for you: less effective
Why manufacturers use it: it's the cheapest form and easy to produce.
Methylcobalamin: the high-quality bioactive form
Used in: high-quality supplements
- natural, bioactive form
- ready for your body to use straight away, with no conversion needed
- highest bioavailability
- particularly effective for the nervous system and brain function
- regulates homocysteine levels (important for cardiovascular health)
Benefits of taking vitamin B12
With the right vitamin B12 product, you can achieve the following:
- less tiredness and exhaustion
- better concentration
- support for your immune system, metabolism and nervous system
- improved vision
There are several factors to consider when you choose the right vitamin B12 product.
Vitamin B12 in true liposomal form
Because they measure just nanometres across and are rich in fats, liposomes protect the vitamin B12 enclosed in them from being broken down by enzymes in saliva and by stomach acid. They deliver vitamin B12 directly into the bloodstream, which significantly improves absorption of the vitamin.
Liposomes are tiny lipid bubbles made of the same substance as human cell membranes. Liposome technology encapsulates nutrients (such as vitamin B12) so that your body doesn't see the encapsulated active ingredient as a 'foreign body'. This lets your body absorb the active ingredients directly into the bloodstream with nothing lost along the way.
The liposomal coating is an innovative solution that lets your body absorb and use far more of the active ingredients.
Because the vitamin is directly available, much lower doses are needed than with conventional products. Studies have found that liposomal vitamin B12 can be absorbed up to 64 times better.
Note: not all liquid products are automatically liposomal.
Simplified model of a liposome with an outer fat layer and a water-filled core. Liposomes are an innovative technology for releasing active ingredients precisely and efficiently. That's why they've earned a firm place in medicine and cosmetics, where they're known for their wide range of uses.
Top 3: the best vitamin B12 supplements on the market
Finding the right vitamin B12 supplement isn't easy.
That's why we assess vitamin B12 supplements against the following six factors:
What is in the vitamin B12 supplement?
Are there any study or test results?
How high is the vitamin dose? (neither too high nor too low)
Does it contain any allergens?
How good is the value for money?
Is there anything special about the formulation or manufacturing?
product review
TESTED
our quality criteria
MELINAVA Vitamin B12
by MELINAVA
Pros
- Liposome technology
- High bioavailability thanks to liposomes (64 times higher)
- Contains bioactive vitamin B12 as methylcobalamin
- 25 µg of premium B12 from the EU
- Active ingredient not destroyed by stomach acid (thanks to the liposomal coating)
- Also contains sea buckthorn extract (vitamin C)
- Vegan
- Made in Europe
- Free from soya, gluten and lactose
- No added preservatives
- No added allergens
- GMO-free
Cons
- Only available online
- Often sold out
Verdict
Melinava Vitamin B12 is high-strength, with 25 µg per daily dose.*
*Because the active ingredient is encapsulated in liposomes, much lower doses are needed than with conventional supplements.
The vitamin B12 it contains is in the active form, methylcobalamin, which stands out for its particularly high bioavailability.
Melinava is one of the strongest over-the-counter vitamin B12 products on the European market.
The formulation and dosage are designed to prevent and relieve a wide range of symptoms.
Modern liposome technology ensures optimal absorption through the gut and into the bloodstream.
This process makes Melinava up to 64 times more bioavailable. Thanks to the liposomal coating, absorption of the liquid B12 formula is not restricted, and intrinsic factor is bypassed.
User satisfaction and the many positive customer reviews of Melinava Vitamin B12 speak for themselves.
Melinava has already produced very good results for symptoms such as lack of energy, depressed mood and muscle weakness, as well as poor concentration and memory.
The manufacturer takes product tolerability very seriously, which is why the supplement is completely free from unwanted additives. You can find more information on the manufacturer's website.
Vanosan B12
by VANOSAN
Pros
- Suitable for acute B12 deficiency
- B12 as cyanocobalamin
- Vegetarian
- Made in the EU
- No added preservatives
- No added allergens
- GMO-free
- Also available in pharmacies
Cons
- Limited absorption
- Not vegan
- Not lactose-free
- Does not contain bioactive vitamin B12
Verdict
Vanosan B12 provides a generous 1,000 µg per daily dose.
Vanosan B12 tablets contain cyanocobalamin, the inactive form of vitamin B12. Your body first has to convert cyanocobalamin into adenosylcobalamin or methylcobalamin.
Users are mostly positive about Vanosan B12. It is well tolerated and helps build up the body's vitamin B12 stores. For many users, taking it over a longer period relieves symptoms such as poor concentration and memory, overtiredness and exhaustion.
Some customers criticise the additives it contains (particularly titanium dioxide). Vanosan B12 contains lactose, so it is not suitable for vegans.
Vanosan B12 is made in the EU and is available online through Amazon and various online pharmacies. Delivery usually takes 2–3 working days.
Vitasprint B12 drinkable vials
by GSK
Pros
- High-strength
- Suitable for acute B12 deficiency
- B12 as cyanocobalamin
- Vegan
- Made in the EU
- No added allergens
- GMO-free
- Also available in pharmacies
Cons
- Does not contain bioactive vitamin B12
- Poor value for money
Verdict
Vitasprint B12 drinkable vials from GSK are high-strength, with 500 µg per daily dose.
Vitasprint contains cyanocobalamin, the inactive form of vitamin B12. Your body first has to convert cyanocobalamin into adenosylcobalamin or methylcobalamin.
Vitasprint is mainly recommended as a longer course to replenish the body's vitamin B12 stores.
Users are mostly positive about Vitasprint B12 drinkable vials. They are well tolerated and bring relief from tiredness, lack of energy and poor concentration. Some customers criticise the vials for breaking easily. Opinions on the raspberry flavour are fairly mixed.
Delivery is free with Amazon Prime and usually takes 1–2 working days. Vitasprint is also available in pharmacies.
Getting enough vitamin B12 is important for strengthening the immune system and reducing the risk of infections and inflammation.
Vitamin B12 and the immune system: how it strengthens your defences
Vitamin B12 plays an important role in a healthy immune system. It contributes to the formation of white blood cells, which defend the body against pathogens. A vitamin B12 deficiency can also weaken the immune system, because the vitamin is needed for cell division and DNA synthesis. Getting enough vitamin B12 may therefore help strengthen the immune system and reduce the risk of infections and illness. It's particularly important for older people, vegetarians and vegans, and people with certain conditions such as Crohn's disease or coeliac disease to make sure they get enough vitamin B12 to support their immune system.
Vitamin B12 also has a major effect on brain function
Vitamin B12 plays an important role in nervous system function and may improve brain function. Getting enough vitamin B12 may support memory and cognitive function and reduce the risk of neurodegenerative diseases such as Alzheimer's and dementia. A 2018 study found that older adults with a higher intake of vitamin B12 had better episodic memory than those with lower B12 levels. It has also been shown that vitamin B12 can improve concentration and attention. Another study, from 2016, found that people with low vitamin B12 levels may be at higher risk of depression and mood disorders, which suggests that vitamin B12 also influences mood regulation.
A deficiency can only be confirmed by medical tests.
Diagnosing vitamin B12 deficiency
Blood test
The most common method is a blood test, but the effects of a deficiency don't show up straight away. Vitamin B12 is stored mainly in the liver, and anaemia caused by a deficiency usually only develops after 2–5 years. That's why a blood test should measure not only vitamin B12 but also holotranscobalamin (holo-TC), serum homocysteine and methylmalonic acid (MMA). If vitamin B12 or holo-TC levels are low, homocysteine or MMA levels should be checked to confirm whether they're raised.
Urine test
The MMA test is cheaper and faster than a blood test. It checks a urine sample for methylmalonic acid. A raised level is a reliable sign of vitamin B12 deficiency, and the MMA test can detect a deficiency at a very early stage.
* We may earn a commission from some of the companies featured. This is how we keep our comparisons free to read.
Some of these companies are our commercial partners.
Sources
- Syed, E. U., Wasay, M., & Awan, S. (2013). Vitamin B12 supplementation in treating major depressive disorder: a randomized controlled trial. The open neurology journal, 7, 44–48. https://doi.org/10.2174/1874205X01307010044
- Köbe, T., Witte, A. V., Schnelle, A., Grittner, U., Tesky, V. A., Pantel, J., Schuchardt, J. P., Hahn, A., Bohlken, J., Rujescu, D., & Flöel, A. (2016). Vitamin B-12 concentration, memory performance, and hippocampal structure in patients with mild cognitive impairment. The American journal of clinical nutrition, 103(4), 1045–1054. https://doi.org/10.3945/ajcn.115.116970
- Leishear, K., Ferrucci, L., Lauretani, F., Boudreau, R. M., Studenski, S. A., Rosano, C., Abbate, R., Gori, A. M., Corsi, A. M., Di Iorio, A., Guralnik, J. M., Bandinelli, S., Newman, A. B., & Strotmeyer, E. S. (2012). Vitamin B12 and homocysteine levels and 6-year change in peripheral nerve function and neurological signs. The journals of gerontology. Series A, Biological sciences and medical sciences, 67(5), 537–543. https://doi.org/10.1093/gerona/glr202
- Koury, M. J., & Ponka, P. (2004). New insights into erythropoiesis: the roles of folate, vitamin B12, and iron. Annual review of nutrition, 24, 105–131. https://doi.org/10.1146/annurev.nutr.24.012003.132306
- Paul, C., & Brady, D. M. (2017). Comparative Bioavailability and Utilization of Particular Forms of B12 Supplements With Potential to Mitigate B12-related Genetic Polymorphisms. Integrative medicine (Encinitas, Calif.), 16(1), 42–49.
- Watanabe, F. (2007). Vitamin B12 sources and bioavailability. Experimental Biology and Medicine, 232(10), 1266-1274. https://doi.org/10.3181/0703-MR-67
- Clarke, R., Smith, A. D., Jobst, K. A., Refsum, H., Sutton, L., & Ueland, P. M. (1998). Folate, vitamin B12, and serum total homocysteine levels in confirmed Alzheimer disease. Archives of Neurology, 55(11), 1449-1455. https://doi.org/10.1001/archneur.55.11.1449