B12 and nerves
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Written By:
Katie Stone - Naturopath
Medical Reviewer:
Kari Asadorian - BSN, RN
Edited By:
Jamie Hope - Methyl-Life® FounderUpdated On:
January 21, 2026B12 and nerves
B12 (cobalamin) plays an essential role as a coenzyme in many biochemical processes that maintain the function of the nervous system. It is especially critical for the DNA synthesis of oligodendrocytes, the cells that produce myelin, as well as the synthesis of myelin itself1. The myelin sheath surrounds the axons of many nerves and acts as an electrical insulation, supporting fast and efficient nerve signaling. This role in myelin formation and remyelination includes the regeneration of nerves after an injury.
B12 is also required for several other processes that support nervous system function, including the conversion of homocysteine to methionine, which can damage the nervous system by generating oxidative stress. B12 is also involved in the synthesis of fatty acids and nucleic acids, energy production, cell maturation and maintenance of the gastrointestinal mucosa.
B12 levels also affect the amount of glutathione in red blood cells and in the liver. Low glutathione and low B12 can increase oxidative stress in the body2.
Causes of neuropathy
- Nutritional deficiencies
B12 is required for regeneration and maintenance of the myelin sheath, while B1 facilitates the metabolism of carbohydrates for energy. B6 plays a key role in the metabolism of nerve cells and the synthesis of neurotransmitters. Deficiency in any of these nutrients can impair the repair and maintenance of nerves as well as the energy they need to function properly, contributing to nerve damage and degeneration.
Neuropathy from vitamin B12 deficiency can occur even without typical signs of B12 deficiency, such as megaloblastic anemia and pancytopenia.3,4
- Health conditions
Diabetes mellitus, inflammatory conditions, autoimmune diseases, infections (eg, Lyme disease, hepatitis C), tumors and hypothyroidism have all been linked to nerve damage and neuropathy. B12 deficiency is common in patients with T2DM, and has been linked to several neurological disorders, including peripheral, autonomic (including cardiovascular) and painful neuropathy, which can accelerate the progression of diabetic neuropathy.
Chronic alcoholism can damage the nerves due to the direct toxic effect of alcohol as well as malnutrition.
- Medications and toxins
Medications such as chemotherapy agents, antibiotics and cardiovascular medications can affect nerve function. Antidiabetic medications such as metformin have also been linked to vitamin B12 insufficiency. Toxins from heavy metals, chemicals and pollutants may also have an impact.
- Physical damage
Trauma or injury in which nerves are stretched, compressed, crushed or cut can impair nerve function.
- Age
Oxidative stress, malnutrition and B12 deficiency is more common in older people, which can increase vulnerability of nerves.
Symptoms of B12-related neuropathy
Neuropathy resulting from B12 deficiency can include:
Peripheral neuropathy
- General fatigue and weakness
- Pain, numbness, tingling, ‘pins and needles’ sensation in the hands and feet
- Impaired motor function, including difficulty walking, muscle weakness and ataxia (reduced physical coordination)
- Optical neuropathy, including blurred vision or vision loss
- Cognitive dysfunction, such as memory loss, difficulty thinking and concentrating
- Mood changes, including depression or delusions
B12 dosage for neuropathy
B12 is one of the most common treatments for neuropathy, and therapeutic doses of 1,000 mcg methylcobalamin per day have been shown to improve nerve symptoms and quality of life.
A 2021 systematic review concluded that there was ‘significant evidence’ for using B12 as part of a treatment plan for neuropathic pain. B12 was found to be particularly effective in treating post-herpetic neuralgia, alcohol-related neuropathy and diabetic neuropathy5.
A 2021 study found that 1,000 mcg methylcobalamin in a sublingual tablet per day for 12 months increased plasma B12 levels in patients with diabetic neuropathy and also improved all neurophysiological symptoms, reduced pain and improved quality of life6.
A 2015 study found that patients treated with 3mg methylfolate, 2 mg methylcobalamin and 35mg P5P experienced significant reduction in their symptoms as well as reduced pain7.
A 2022 study involving patients with fibromyalgia found that a short course of sublingual vitamin B12, 1,000 mcg daily, significantly improved the severity of fibromyalgia symptoms as well as the patient's anxiety8.
Nerve pain as a symptom of B12 deficiency
Nerve pain due to B12 deficiency is not usually one of the early symptoms. It may take some months or years to develop, depending on the severity of the deficiency and the cause.
Initial symptoms of B12 deficiency are usually linked to reduced red blood cell production and include fatigue, low mood, reduced concentration, shortness of breath and palpitations.
Untreated B12 deficiency may lead to damage or deterioration of the myelin sheath surrounding nerve fibres. This can then manifest as neurological symptoms such as numbness and tingling in the extremities and nerve pain.
B12 for nerve damage
Vitamin B12’s role in regenerating myelin and supporting nerve health has made it a standard clinical treatment for nerve damage. Clinical trials show that supplementation with B12 improves axon growth of neuronal cells after peripheral nerve injury, promotes nerve cell survival and is directly involved in remyelination and the maintenance of myelin sheath9
B12 is thought to alleviate nerve pain via several mechanisms, including promoting myelination, increasing nerve regeneration and decreasing ectopic nerve firing. A 2020 systematic review found evidence for B12 as a drug treatment for neuropathic pain, particularly post-herpetic neuralgia and the treatment of painful peripheral neuropathy.
In a study involving patients with traumatic brain injury, B12 improved nerve function by reducing stress-related apoptosis. It also restored microtubule stability and supported myelin repair, similar to the effects of 4-phenylbutyric acid (a medication for treating urea cycle disorders)10.
B12 for nerve regeneration
B12 is a neurotrophic substance with an affinity for neuronal tissues, and plays a central role in maintaining and regenerating peripheral nerves. By promoting the process of myelination, B12 supplementation is shown to lead to functional restoration. Numerous studies show that B12 supports healthy nerve regeneration and is directly involved in remyelination and the maintenance of myelin sheaths11. It also appears to decrease ectopic nerve firing, which could explain why it helps alleviate painful symptoms12
Earlier studies show that high-dose vitamin B12 promotes neurite outgrowth and neuronal survival, as well as increasing extracellular signal-regulated kinases and Akt signaling after sciatic nerve injury. It also promoted functional recovery of nerves13
Vitamin B12 was found to promote functional recovery and axonal regeneration in patients with sciatic nerve injury, as well as attenuating edema and myelin sheath degeneration14.
A similar study found that B12 promoted functional recovery and histological regeneration of the injured sciatic nerve and its target muscle after sciatic nerve injury15.
B12 and nerves
Key takeaways
-
B12 is essential for maintaining the health and function of nerves and repairing myelin.
-
Chronic B12 deficiency can lead to neurological symptoms including fatigue and motor impairments.
-
High-dose methylcobalamin (MeCbl) is shown to be effective in improving nerve pain and supporting nerve recovery.
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Frequently Asked Questions about B12 and neuropathy
Clinical research has suggested that B12 is effective in treating nerve pain and regenerating the myelin sheath surrounding nerve fibres.
There is no specific B12 dosage for treating neuropathy, as every case is different. However, studies have shown that 1,000 mcg methylcobalamin daily is effective in reducing nerve pain and improving other symptoms associated with nerve damage16.
Yes, several studies have suggested that supplementation with active B12 (methylcobalamin) can help to reduce nerve pain resulting from B12 deficiency. However, it’s important to first determine the cause of the nerve pain, as every case is different.
Neurological symptoms (affecting the nervous system) that can result from prolonged B12 deficiency include general fatigue and weakness, along with pain, numbness and tingling in the hands and feet. Motor function may become impaired, resulting in difficulty walking, muscle weakness and reduced physical coordination. Cognitive dysfunction, such as memory loss, difficulty thinking and concentrating may also develop, along with mood changes such as depression or delusions.
These symptoms can occur even without anemia and highlight the importance of early detection to avoid irreversible damage.
References
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Carlos Alberto Calderón‐Ospina, Mauricio Orlando Nava‐Mesa; "B Vitamins in the nervous system: Current knowledge of the biochemical modes of action and synergies of thiamine, pyridoxine, and cobalamin"; CNS neuroscience & therapeutics; 2019 Sep
https://pmc.ncbi.nlm.nih.gov/articles/PMC6930825/
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Aimee Rachel Mathew, Giacomo Di Matteo, Piergiorgio La Rosa, Saviana Antonella Barbati, Luisa Mannina, Sandra Moreno, Ada Maria Tata, Virve Cavallucci, Marco Fidaleo; "Vitamin B12 Deficiency and the Nervous System: Beyond Metabolic Decompensation—Comparing Biological Models and Gaining New Insights into Molecular and Cellular Mechanisms"; International journal of molecular sciences; 2024 Jan
https://pmc.ncbi.nlm.nih.gov/articles/PMC10778862/
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Ahmed, M. A.; "Metformin and Vitamin B12 Deficiency: Where Do We Stand?"; Journal of Pharmacy & Pharmaceutical Sciences; 2016
https://journals.library.ualberta.ca/jpps/index.php/JPPS/article/view/27581
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Dissanayake Mudiyanselage Priyantha Udaya Kumara Ralapanawa, Kushalee Poornima Jayawickreme, Ekanayake Mudiyanselage Madhushanka Ekanayake, Widana Arachchilage Thilak Ananda Jayalath; "B12 deficiency with neurological manifestations in the absence of anaemia"; BMC research notes; 2015 Sep
https://pmc.ncbi.nlm.nih.gov/articles/PMC4575440/
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Thomas Julian, Rubiya Syeed, Nicholas Glascow, Efthalia Angelopoulou, Panagiotis Zis; "B12 as a Treatment for Peripheral Neuropathic Pain: A Systematic Review"; Nutrients; 2020 Jul
https://pmc.ncbi.nlm.nih.gov/articles/PMC7468922/
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Triantafyllos Didangelos, Eleni Karlafti, Evangelia Kotzakioulafi, Eleni Margariti, Parthena Giannoulaki, Georgios Batanis, Solomon Tesfaye, Kοnstantinos Kantartzis; "Vitamin B12 Supplementation in Diabetic Neuropathy: A 1-Year, Randomized, Double-Blind, Placebo-Controlled Trial"; Nutrients; 2021
https://www.mdpi.com/2072-6643/13/2/395#B21-nutrients-13-00395
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Bruce S. Trippe, Lori W. Barrentine, Melanie V. Curole, Eleanor Tipa; "Nutritional management of patients with diabetic peripheral neuropathy with L-methylfolate-methylcobalamin-pyridoxal-5-phosphate: results of a real-world patient experience trial"; Current Medical Research and Opinion; 2016
https://www.tandfonline.com/doi/full/10.1185/03007995.2015.1103215
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Faeze Gharibpoor, Banafsheh Ghavidel-Parsa, Nazila Sattari, Ali Bidari, Fatemeh Nejatifar, Ali Montazeri; "Effect of vitamin B12 on the symptom severity and psychological profile of fibromyalgia patients; a prospective pre-post study"; BMC rheumatology; 2022 Sep
https://pmc.ncbi.nlm.nih.gov/articles/PMC9434892/
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Simone Baltrusch; "The Role of Neurotropic B Vitamins in Nerve Regeneration"; BioMed research international; 2021 Jul
https://pmc.ncbi.nlm.nih.gov/articles/PMC8294980/
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Fangfang Wu, Ke Xu, Lei Liu, Kairui Zhang, Leilei Xia, Man Zhang, Chenhuai Teng, Heyan Tong, Yifang He, Yujie Xue, Hongyu Zhang, Daqing Chen, Aiping Hu; "Vitamin B12 Enhances Nerve Repair and Improves Functional Recovery After Traumatic Brain Injury by Inhibiting ER Stress-Induced Neuron Injury"; Frontiers in pharmacology; 2019 Apr
https://pmc.ncbi.nlm.nih.gov/articles/PMC6491933/
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Simone Baltrusch; "The Role of Neurotropic B Vitamins in Nerve Regeneration"; BioMed Research International; 2021 Jul
https://onlinelibrary.wiley.com/doi/10.1155/2021/9968228
-
Thomas Julian, Rubiya Syeed, Nicholas Glascow, Efthalia Angelopoulou, Panagiotis Zis; "B12 as a Treatment for Peripheral Neuropathic Pain: A Systematic Review"; Nutrients; 2020
https://www.mdpi.com/2072-6643/12/8/2221
-
Kiyoshi Okada, Hiroyuki Tanaka, Ko Temporin, Michio Okamoto, Yusuke Kuroda, Hisao Moritomo, Tsuyoshi Murase, Hideki Yoshikawa; "Methylcobalamin increases Erk1/2 and Akt activities through the methylation cycle and promotes nerve regeneration in a rat sciatic nerve injury model"; Experimental neurology; 2010 Apr
https://pubmed.ncbi.nlm.nih.gov/20045411/
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Bahriye Horasanli, Askin Esen Hasturk, Murat Arikan, Guray Togral, Fatma Helvacioglu, Atilla Dagdeviren, Senem Mut, Ferhat Harman, Guldeniz Argun; "Comparative evaluation of the electrophysiological, functional and ultrastructural effects of alpha lipoic acid and cyanocobalamin administration in a rat model of sciatic nerve injury"; Journal of back and musculoskeletal rehabilitation; 2017 Sep
https://pubmed.ncbi.nlm.nih.gov/28968230/
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Ying Yuan, Hongmei Shen, Jian Yao, Nan Hu, Fei Ding, Xiaosong Gu; "The protective effects of Achyranthes bidentata polypeptides in an experimental model of mouse sciatic nerve crush injury"; Brain research bulletin; 2010 Jan
https://pubmed.ncbi.nlm.nih.gov/19646511/
-
Triantafyllos Didangelos, Eleni Karlafti, Evangelia Kotzakioulafi, Eleni Margariti, Parthena Giannoulaki, Georgios Batanis, Solomon Tesfaye, Kοnstantinos Kantartzis; "Vitamin B12 Supplementation in Diabetic Neuropathy: A 1-Year, Randomized, Double-Blind, Placebo-Controlled Trial"; Nutrients; 2021
https://www.mdpi.com/2072-6643/13/2/395#B21-nutrients-13-00395
About the Author
Katie is a qualified Naturopath (BNatMed) and freelance writer from New Zealand. She specializes in all things health and wellness, particularly dietary supplements and nutrition. Katie is also a dedicated runner and has completed more half-marathons than she can count!
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