The role of diet and non‐pharmacologic supplements in the treatment of chronic neuropathic pain: A systematic review

Abstract

Background/ImportanceDietary interventions, vitamins, and nutritional supplementation are playing an increasingly important role in the management of neuropathic pain. Current pharmacological treatments are poorly tolerated and ineffective in many cases.ObjectiveThis systematic review aims to study the efficacy of dietary interventions, vitamins, and nutritional supplementation in the management of chronic neuropathic pain in adults.Evidence ReviewThe review followed PRISMA guidelines and was registered with PROSPERO (#CRD42022300312). Ten databases and gray literature, including Embase.com, MEDLINE and Web of Science, were systematically searched using a combination of keywords and controlled vocabulary related to chronic neuropathic pain and oral non‐pharmacological supplements. Studies on adult humans published between 2000 and 2021 were considered for inclusion. The Cochrane Handbook was used to assess risk of bias, and Grading of Recommendations Assessment, Development, and Evaluation was used to determine overall quality of evidence.FindingsForty studies were included in the final review, and results were categorized according to pain type including pain related to chemotherapy‐induced peripheral neuropathy (CIPN, 22 studies, including 3 prospective cohorts), diabetic peripheral neuropathy (DPN, 13 studies, including 2 prospective), complex regional pain syndrome (CRPS‐I, 3 studies, including 1 prospective), and other (2 studies, both RCT). The CIPN studies used various interventions including goshajinkigan (4 studies), vitamin E (5), vitamin B12 (3), glutamine (3), N‐acetyl‐cysteine (2), acetyl‐l‐carnitine (2), guilongtonluofang (1), ninjin'yoeito (1), alpha‐lipoic acid (1), l‐carnosine (1), magnesium and calcium (1), crocin (1), and antioxidants (1), with some studies involving multiple interventions. All CIPN studies involved varying cancers and/or chemotherapies, advising caution for generalizability of results. Interventions for DPN included alpha‐lipoic acid (5 studies), vitamin B12 (3), acetyl‐l‐carnitine (3), vitamin E (1), vitamin D (2), and a low‐fat plant‐based diet (1). Vitamin C was studied to treat CRPS‐I (3 studies, including 1 prospective). Magnesium (1) and St. John's wort (1) were studied for other or mixed neuropathologies.ConclusionsBased on the review, we cannot recommend any supplement use for the management of CIPN, although further research into N‐acetyl‐cysteine, l‐carnosine, crocin, and magnesium is warranted. Acetyl‐l‐carnitine was found to be likely ineffective or harmful. Alpha‐lipoic acid was not found effective. Studies with goshajinkigan, vitamin B12, vitamin E, and glutamine had conflicting results regarding efficacy, with one goshajinkigan study finding it harmful. Guilongtonluofang, ninjin'yoeito, and antioxidants showed various degrees of potential effectiveness. Regarding DPN, our review supports the use of alpha‐lipoic acid, acetyl‐l‐carnitine, and vitamin D. The early use of vitamin C prophylaxis for the development of CRPS‐I also seems promising. Further research is warranted to confirm these findings.

Modern view on the use of alpha lipoic acid in neurological practice

“…К аналогичным выводам пришли и авторы метаанализа 20 исследований, посвященных монотерапии АЛК и эпалрестатом и комбинированной терапии этими же препаратами [51]. J.K. Frediani et al также рекомендуют использование АЛК в терапии ДПН на основании анализа 40 исследований, изучавших эффективность диеты, витаминотерапии, АЛК и пищевых добавок в лечении хронической нейропатической боли у взрослых [52]. В то же время авторы одного из обзоров указывают, что АЛК, вероятно, оказывает незначительное влияние или вообще не влияет на симптомы нейропатии, но при этом считают необходимым продолжить дальнейшие исследования [53].…”

The Safety of Drug Treatment in Patients with Neuropathic Pain: Data from Ambulatory Care in a Real-Life Setting

“…To reduce the development of ADRs, which could be also related to the dosage and the long duration of treatment, a nonpharmacological treatment has been suggested. Nutrients are commonly used in patients with pain, e.g., Acetyl-L-carnitine [14][15][16][17][18][19][20], palmitoylethanolamide (PEA) [21][22][23][24][25][26][27], and alpha-lipoic acid [28][29][30][31][32][33][34][35].…”