A narrative review of complementary nutritional supplements for chemotherapy-induced peripheral neuropathy

Background • Chemotherapy-induced peripheral neuropathy (CIPN) is a common troublesome side effect and affects long-term activities of daily living. This neuropathic disorder is still difficult to treat with current clinical treatments. The aim of this study was to investigate and offer an updated perspective of complementary therapies for CIPN. Methods • This review included current databases, including PubMed, Embase, the Cochrane Database, Google Scholar, and Ovid Medline, published up to May 2019 in the English language, to summarize the role of nutrient supplements in CIPN, based on evidence from both animal and clinical studies. Results • A total of 58 studies were included in this review. There were 19 preclinical studies that reported mechanisms of effects and 31 clinical studies corroborated preclinical findings, including 22 randomized controlled trials and 3085 patients with CIPN. Interventions included vitamin E, vitamin B complex, glutamine, acetyl-L-carnitine, alpha lipoic acid, glutathione, omega-3 fatty acids, and calcium/ magnesium (Ca²⁺ /Mg²⁺ ). The administration of various nutrients remains inconsistent, and limited evidence of effective ones for treating CIPN is available. However, glutamine and omega-3 fatty acids present potential as treatment options for CIPN. The evidence on vitamin E and vitamin B complex is inconclusive, and some forms of vitamin B, such as B₆ or B₁₂, await confirmation of their potential to offer protection from CIPN. Less robust evidence was found for nutrients such as acetyl-L-carnitine, α-Lipoic acid, glutathione, and Ca²⁺/Mg²⁺ for CIPN. Conclusion • Nutritional therapists seem to recommend nutrient supplements as potential anti-inflammatory and neuroprotective agents for both the prevention and management of CIPN. An understanding of this evolving literature is useful in exploring these therapies with patients who are considering using them. However, their effects against CIPN are still controversial due to the undetermined neuropathic mechanisms of different antineoplastic agents and complex drug interactions. Further research on these agents is warranted.