Diet can exert both analgesic and pronociceptive effects in acute and chronic pain models: a systematic review of preclinical studies

Background Although diet is an essential aspect of human health, the link between diet and pain is still not well understood. Preclinical animal research provides information to understand underlying mechanisms that allow identifying the needs for human research. Objectives This study aims to give a systematic overview of the current evidence from preclinical studies regarding the analgesic and pronociceptive effects of various diets in non-neuropathic, non-cancer, or non-visceral acute and chronic pain models. Study Design A systematic Review Setting This study examined studies that investigate the analgesic and pronociceptive effects of various diets in non-neuropathic, non-cancer, or non-visceral acute and chronic pain models. Methods This review was conducted following the PRISMA guidelines and was registered in PROSPERO with the registration number CRD42019133473. The certainty of evidence was examined by a modified GRADE approach. Results After the screening process twenty-four eligible papers were included in this review. Nineteen studies examined acute pain, nine studies chronic inflammatory pain, and four studies assessed both acute and chronic pain models. Limitations Due to the heterogeneity of the included studies, a meta-analysis was not included in this study. Conclusions In animal models, excessive saturated, monounsaturated or omega-6 polyunsaturated fat ingestion and diets rich in fats and carbohydrates can decrease pain sensitivity in acute nociceptive pain, whereas it can induce mechanical allodynia and heat hyperalgesia in chronic inflammatory pain. Additionally, diets rich in anti-inflammatory ingredients, as well as a calorie-restricted diet can promote recovery from primary mechanical allodynia and heat hyperalgesia in chronic inflammatory pain.