Vitamin B Complex

In the literature, there are indications that the medicinal intake of vitamin preparations from the group of the vitamin B complex could support nerve healing.  These include vitamins B1, B6, and B12. These can be found as individual preparations, but also as combination preparations for daily use. If you would like to support your nerve healing with a vitamin preparation, please read the package insert and ask your family doctor and pharmacist.

Evidence for this was found in the literature in the following studies:
In experimental studies on Schwann cells of rats, positive effects on the improved regeneration of the myelin sheaths through the administration of vitamin B1/6/12 could be demonstrated. After acute injuries, lower values were found in the course[1] (Table 1), so that substitution can be useful in acute cases.

The administration of vitamin B complex, in particular vitamin B12 in its active form, methylcobalamin[2], increases the myelination of the nerve fibers and increases the number of Schwann cells via intracellular signaling pathways[3].

In in-vitro studies, it could be shown that only high doses of methylcobalamin have an antiapoptotic effect[5]. Apoptosis (ancient Greek ἀπόπτωσις apóptosis, from ἀποπίπτειν apopíptein 'fall off') is a form of programmed cell death. In diabetic neuropathy, no significant electrophysiological effect on nerve regeneration could be demonstrated with oral administration (in different doses), but a subjective improvement of the symptoms was observed[6].

Source: Altun I, Kurutaş EB. Vitamin B complex and vitamin B 12 levels after peripheral nerve injury. Neural Regen Res 2016;11:842-5. doi:10.4103/1673-5374.177150.

sources:
[1] Altun I, Kurutaş EB. Vitamin B complex and vitamin B 12 levels after peripheral nerve injury. Neural Regen Res 2016;11:842-5
[2] Weir D. G., Scott J. M. (1995). The biochemical basis of the neuropathy in cobalamin deficiency. Baillieres Clin. Haematol. 8 479–497. 10.1016/S0950-3536(05)80217-3
[3] Lopatina T, Kalinina N, Karagyaur M, Stambolsky D, Rubina K, Revischin A, Pavlova G, Parfyonova Y, Tkachuk V (2011) Adipose-derived stem cells stimulate regeneration of peripheral nerves: BDNF secreted by these cells promotes nerve healing and axon growth de novo. PLoS One 6:e17899.   
[4] Corinne G, Mizisin LM, Austin N (2009) B vitamins alleviate indices of neuropathic pain in diabeticrats. Eur J Pharmacol 612:41-47.
[5] Methylcobalamin increases Erk1/2 and Akt activities through the methylation cycle and promotes nerve regeneration in a rat sciatic nerve injury model
[6] Effectiveness of vitamin B12 on diabetic neuropathy: systematic review of clinical controlled trials.Y Sun, MS Lai, and CJ Lu.