Peripheral neuropathy may be caused by widespread deficiencies of two B vitamins

Peripheral neuropathy can cause numbness, abnormal sensations, nerve pain, muscle fatigue, cramps, and difficult-to-heal wounds. Diabetic neuropathy also increases the risk of amputation. Peripheral neuropathy is a major global health problem, and according to a review article published in Current Nutrition Reports, deficiencies of vitamins B1 and B12 are associated with the classic forms of peripheral neuropathy.

Peripheral neuropathy is a general term for disorders or damage affecting the peripheral nervous system, particularly the sensory nerves and muscles. Typical symptoms include altered sensation, numbness, and burning or stabbing pain. Muscle fatigue and muscle cramps may also occur. Diabetic neuropathy increases the risk of foot ulcers and gangrene, and in the most severe cases, amputation of toes, feet, or legs may be necessary.
Common causes of peripheral neuropathy include poor dietary habits, excessive alcohol consumption, and metabolic disorders such as diabetes. Other causes include infections, autoimmune disorders, chemotherapy, and exposure to toxins.
Nutritional status plays an important role in the development of various types of peripheral neuropathy. In this review, the researchers therefore examined the relationship between peripheral neuropathy and deficiencies of vitamins B1, B6, B12, and B9 (folate), all of which are essential for normal nervous system function.
Overall, the review found that deficiencies of vitamins B1 and B12 are significantly associated with the development of the classic forms of peripheral neuropathy. The evidence linking vitamins B6 and B9 (folate) to peripheral neuropathy was less consistent. The following is a brief overview of the roles of vitamins B1 and B12 in nervous system function, together with the major dietary sources, common causes of deficiency, and requirements.

The role of vitamin B1 in nervous system function

Vitamin B1 (thiamine) is essential for cellular energy metabolism, including energy production in nerve cells. It also plays an important role in the normal function of neurotransmitters. As a result, vitamin B1 is vital for the nervous system and for the transmission of signals to the brain, cardiovascular system, muscles, heart, and other organs. A deficiency of vitamin B1 can cause neurological disorders such as beriberi, the classic deficiency disease, and Wernicke's encephalopathy, a life-threatening neurological condition.

Sources of vitamin B1, causes of deficiency, and requirements

Good dietary sources of vitamin B1 include whole grains, nuts, mushrooms, vegetables, meat, and fish. It is estimated that around 30% of the world's population is deficient in vitamin B1, primarily because of diets high in ultra-processed foods and/or excessive alcohol consumption. Persistently elevated blood glucose levels, as seen in type 2 diabetes and the metabolic syndrome, may also increase urinary loss of vitamin B1.
Acid-suppressing medications and diuretics can likewise impair vitamin B1 utilization through different mechanisms. In addition, inherited or acquired genetic factors may increase an individual's requirement for vitamin B1.
The recommended daily intake (RI) is 1.1-1.3 mg, but according to several researchers this may not always be sufficient to optimize vitamin B1 status. Consequently, a number of clinical studies have used much higher daily doses to address deficiency-related symptoms and conditions, including peripheral neuropathy.

The role of vitamin B12 in nervous system function

Vitamin B12 is essential for red blood cell formation, DNA synthesis, fatty acid metabolism, and the production of myelin, the cholesterol-rich sheath that protects nerve fibers. Together with vitamins B6 and B9, vitamin B12 also helps break down the amino acid homocysteine, which in elevated concentrations may damage both the nervous system and the cardiovascular system.
A deficiency of vitamin B12 may therefore lead to anemia and peripheral neuropathy - including diabetic neuropathy - as well as dementia and other forms of cognitive impairment.

Sources of vitamin B12, causes of deficiency, and requirements

Vitamin B12 is found naturally only in meat, fish, eggs, and other animal-derived foods. Its absorption in the small intestine depends on the presence of a transport protein known as intrinsic factor. Because vitamin B12 is the only B vitamin that can be stored in the body, it may take several months - or even more than a year - for a deficiency caused by a restrictive or plant-based diet to become clinically apparent.
The recommended daily intake (RI) is 2.5 micrograms, yet an estimated 39% of the world's population is deficient in vitamin B12 for a variety of reasons. Medications such as metformin, used to treat type 2 diabetes, and proton pump inhibitors (PPIs), used to reduce stomach acid, can impair the absorption or utilization of vitamin B12. The same may occur as a result of aging, certain gastrointestinal disorders, or gastrointestinal surgery.
When taking supplements, vitamin B12 is most easily absorbed from sublingual lozenges, which allow the vitamin to be absorbed directly through the oral mucosa.

Learn more about vitamin D and diabetic neuropathy

In the following article, you can read more about how widespread vitamin D deficiency may also increase the risk of diabetic neuropathy.

• Lack of vitamin D is linked to diabetic neuropathy

References:

Mauricio Alvarez et al. B Vitamin Deficiencies and Associated Neuropathies. Current Nutrition Reports. 2026

Julia Kazmierczak-Baranska et al. Thiamine (vitamin B1) – An Essential Health Regulator. Nutrients 2025

Thomas Julian et al. B12 as a Treatment for Peripheral Neuropathic Pain: A systematic Review. Nutrients. 2020

Simone Passarelli et al. Global estimation of dietary micronutrient inadequacies: a modeling analysis. The Lancet Global Health 2024