Guide
Constantly exhausted? A vitamin B12 deficiency could be why (2026)
Last updated: 4 August 2026
Written by
Health Tested Editorial Team
Do you feel exhausted all the time? A vitamin B12 deficiency could be behind it.
The catch: most B12 supplements aren't absorbed by the body at all.Signs you could have a vitamin B12 deficiency
A deficiency can cause the following symptoms:
- feeling constantly tired or low on energy
- difficulty concentrating or brain fog
- lack of motivation
- weakness or reduced stamina
- exhaustion despite getting enough sleep
It can also cause mental and emotional symptoms:
- low mood
- mood swings
- nervousness and irritability
→ If this sounds familiar, vitamin B12 may help.
Who is most likely to have a vitamin B12 deficiency?
These groups are most at risk:
- people under chronic stress
- vegetarians and vegans
- people over 40
- people with digestive problems
- people who have tried iron, magnesium or sleeping pills without success
Why ordinary vitamin B12 often does not work
The problem isn't the dose. It's the absorption.Why conventional vitamin B12 often fails:
- ✗ most of it is destroyed by stomach acid
- ✗ absorption falls with age and stress
- ✗ many people absorb B12 poorly
Why liposomal B12 is better:
- ✓ bypasses the digestive barriers
- ✓ better bioavailability
- ✓ more consistent absorption
- ✓ easy to take, as it comes in liquid form (especially convenient if you can't swallow tablets)
Conventional B12 supplements have a long journey through your body:
1. Mouth and saliva: enzymes begin to break down the active ingredient
2. Stomach acid: up to 99% is destroyed here
3. Gut: only 1–2% can still be absorbed
Liposomes solve this problem
Liposomes are tiny bubbles of fat that wrap around the vitamin B12 like a protective capsule.
They're made of the same material as your cell membranes, so your body doesn't treat them as foreign.
- Protection from stomach acid:
The liposome shell stops the B12 from being broken down
- Straight into the blood:
Bypasses the gut entirely
- Liquid form:
Easy to take
What you can realistically expect
Before:
- low energy
- exhaustion
- brain fog
- lack of drive
After 3–4 weeks:
- ✓ more stable energy
- ✓ better concentration
- ✓ less tiredness
- ✓ better performance
Results vary depending on how deficient you are to begin with and how consistently you take it.
What customers say about Melinava Vitamin B12
'After two weeks I was much less tired during the day. No more afternoon slump.'
Ursula, 67
'My energy levels are much more stable now, and I can concentrate better again.'
Murat, 29
'I no longer feel constantly exhausted, even though I'm not sleeping any more than before.'
Roland, 45
Our top pick for 2026: Melinava Vitamin B12
product review
TESTED
our quality criteria
MELINAVA Vitamin B12
by MELINAVA
Pros
- Liposome technology
- Up to 64 times higher bioavailability thanks to liposomes
- Contains bioactive vitamin B12 as methylcobalamin
- 25 µg of high-quality B12 from the EU
- The active ingredient is not destroyed by stomach acid (thanks to the liposomal coating)
- Also contains sea buckthorn extract (vitamin C)
- Vegan
- Made in Germany
- 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 a high-strength supplement, 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. This form is known for its particularly high bioavailability.
Melinava is one of the strongest over-the-counter vitamin B12 products on the European market.
Its innovative liposome technology ensures the vitamin is optimally absorbed in the gut and passes from there into the bloodstream.
This makes Melinava up to 64 times more bioavailable than conventional B12. Thanks to the liposomal coating, the liquid B12 bypasses intrinsic factor, so its absorption is not restricted.
The many positive customer reviews of Melinava Vitamin B12 speak for themselves.
People have already used Melinava with very good results for symptoms such as lack of energy, low mood, muscle weakness, and poor concentration and memory.
Frequently asked questions
How long does it take to notice results?
Most people notice the first improvements in energy and concentration after 2–4 weeks. With a severe deficiency, it can take 6–8 weeks for the body's stores to be replenished.
How do I take liposomal vitamin B12?
Squeeze two full droppers directly into your mouth each day. Alternatively, stir the drops into water, juice or even tea or coffee.
Can I take it every day?
Yes. Melinava is designed to be taken every day. Vitamin B12 is water-soluble, so any excess is simply excreted. An overdose is practically impossible.
Is liposomal B12 better than conventional B12?
Yes. Up to 99% of conventional vitamin B12 is destroyed by stomach acid. Liposomal B12 bypasses this barrier and is absorbed up to 64 times better.
Who should not take B12?
Vitamin B12 is safe for most people. If you have a known allergy to any of the ingredients or a serious pre-existing condition, talk to your doctor first. Pregnant and breastfeeding women can take B12 without concern.
Can I combine it with other supplements?
Yes. Vitamin B12 combines well with other vitamins and minerals. It even enhances the effect of folic acid and iron.
Are there any side effects?
Vitamin B12 is very well tolerated. In rare cases, mild skin reactions can occur. Because it's water-soluble, any excess is simply excreted, so side effects from an overdose are extremely rare.
Is the product vegan?
Yes. Melinava is 100% vegan and free from allergens, gluten, lactose and additives. It is also top quality and laboratory-tested.
Shop Melinava Vitamin B12Sources
- 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