Vitamin B Complex

Correcting specific deficiencies that cause neuropathy.

• B12 (cobalamin): Deficiency is a classic, reversible cause of peripheral neuropathy; B12 is essential for myelin synthesis and axonal integrity. Treating deficiency improves neurological symptoms. AAFP

• B1 (thiamine): Thiamine deficiency can cause neuropathy; the lipid-soluble thiamine prodrug benfotiamine may reduce hyperglycemia-related nerve injury by activating transketolase and diverting glycolytic intermediates away from pathways that generate AGEs and oxidative stress. Diabetes Journals

• B6 (pyridoxine): Adequate B6 is needed for neurotransmitter synthesis; however, excess B6 can cause neuropathy (see warnings). Office of Dietary Supplements

Don’t self-treat first—check the cause. Ask a clinician to look for reversible causes (diabetes control, alcohol use, medications like metformin, thyroid/kidney disease) and test B12 (with MMA if needed) before starting supplements—particularly important because folate can mask hematologic signs of B12 deficiency while neuropathy worsens. BMJ

If B12 deficiency is confirmed or strongly suspected:

• Typical UK/NICE-aligned regimens use hydroxocobalamin 1,000 µg IM as a loading course (several injections over 1–2 weeks) followed by 1,000 µg IM every 2–3 months for maintenance when malabsorption is present or neurological involvement exists; high-dose oral B12 (≥1 mg/day) is reasonable in some cases. Clinicians tailor frequency to symptoms and labs. NICE

If thiamine support is considered (e.g., diabetes with symptoms, alcohol misuse, or low thiamine):

• Trials most often used benfotiamine 300–600 mg/day for 6–12 weeks; longer studies have used 300 mg/day up to 24 months (results mixed—see “Studies”). Discuss an on-label thiamine vs. benfotiamine trial with your clinician. Real Health Products

Be very careful with B6 (pyridoxine).

• In Australia, the TGA requires a neuropathy warning on products with >10 mg/day of B6; total daily intake from all supplements should be reviewed. The NIH ODS notes EFSA’s newer upper limit of 12 mg/day for adults; excess B6 can injure peripheral nerves. Prefer B-complex formulas that keep B6 ≤10–12 mg/day unless specifically prescribed. Therapeutic Goods Administration (TGA)

If you’re on metformin:

• Long-term metformin is associated with B12 deficiency; major diabetes guidelines recommend periodic B12 testing, especially if neuropathy or anemia is present. Diabetes Journals

Combine with standard neuropathy care.

• For diabetic neuropathy: optimize glycemic control and foot care per ADA Standards of Care; vitamins are adjuncts, not substitutes. Advanced Oxygen Therapy Inc.

Systematic reviews & overviews

• Cochrane review on B-vitamins for peripheral nerve disorders: limited, low-certainty benefit overall; one short benfotiamine study suggested modest improvement in vibration threshold. Cochrane

• 2022 BMJ Open protocol is assessing B-complex + alpha-lipoic acid (shows active interest; not results). BMJ Open

• 2021 systematic review on B-vitamins in diabetic neuropathy: evidence heterogeneous; benefits not consistent across outcomes. ScienceDirect

Benfotiamine (B1 prodrug)

• BENDIP (6 weeks, n≈124 analyzed): 600 mg/day improved Neuropathy Symptom Score vs placebo. Short-term symptomatic benefit. Real Health Products

• BOND (12 months protocol in symptomatic DSPN): long-term morphometric/neurophysiologic endpoints under study (protocol published; not definitive efficacy). BMJ Open

• Type 1 diabetes, 24 months (300 mg/day): no improvement in nerve conduction or inflammatory markers vs placebo. Europe PMC

B12 (methylcobalamin/cyanocobalamin/hydroxocobalamin)

• Metformin-treated T2D with low-normal B12 (Nutrients 2021, 1 mg oral MeCbl daily for 1 year, n=90): improved neuropathy measures vs placebo. MDPI

• Metanx® (L-methylfolate 3 mg + MeCbl 2 mg + P5P 35 mg; 24 weeks, n=214): primary endpoint (vibration threshold) not met, but symptom scores improved vs placebo (secondary outcomes). American Journal of Medicine