Low-carbohydrate and ketogenic diets: a scoping review of neurological and inflammatory outcomes in human studies and their relevance to chronic pain

Abstract

Dietary restriction of carbohydrate has been demonstrated to be beneficial for nervous system dysfunction in animal models and may be beneficial for human chronic pain. The purpose of this review is to assess the impact of a low-carbohydrate/ketogenic diet on the adult nervous system function and inflammatory biomarkers to inform nutritional research for chronic pain. An electronic data base search was carried out in May 2021. Publications were screened for prospective research with dietary carbohydrate intake <130g/day and duration of ≥2 weeks. Studies were categorised into those reporting adult neurological outcomes to be extracted for analysis and those reporting other adult research outcomes Both groups were screened again for reported inflammatory biomarkers. From 1548 studies there were 847 studies included. Sixty-four reported neurological outcomes with 83% showing improvement. Five hundred and twenty-three studies had a different research focus (metabolic n=394, sport/performance n=51, cancer n=33, general n=30, neurological with non-neuro outcomes n=12, or gastrointestinal n=4). The second screen identified 63 studies reporting on inflammatory biomarkers with 71% reporting a reduction in inflammation. The overall results suggest a favourable outcome on the nervous system and inflammatory biomarkers from a reduction in dietary carbohydrates. Both nervous system sensitisation and inflammation occur in chronic pain and the results from this review indicate it may be improved by low-carbohydrate nutritional therapy. More clinical trials within this population are required to build on the few human trials that have been done.

Low and high carbohydrate isocaloric diets on performance, fat oxidation, glucose and cardiometabolic health in middle age males

“…Paramount to both athletes and the general population is the potential health and disease implication of their dietary choice, particularly as individuals advance in age. Multiple studies have illustrated beneficial shifts in glucose, insulin, hemoglobin A 1c (HbA 1c ), inflammation, and oxidative stress biomarkers, along with proposed alterations in diabetes, cancer, neurological, and other disease clinical outcomes resulting from LCHF diets and their resulting metabolite shifts (33)(34)(35)(36)(37)(38)(39)(40). While there is evidence for optimism, some dating back over a century (36,38), there has been a call for more high-quality evidence (41).…”

Dietary Effects on Pain Symptoms in Patients with Fibromyalgia Syndrome: Systematic Review and Future Directions

“…Additionally, diets other than those included in this review may also result in pain improvement. For instance, low-carbohydrate and ketogenic diets were recently hypothesized to alleviate chronic pain, also through inflammatory and nervous system pathways [ 31 ], and other diets also need to be investigated in future studies of pain symptoms among FMS patients.…”

Ketogenic diets for obesity‐hypoventilation syndrome? Interesting physiology but a long way to go

“…Until recently, the use of KDs as a nutritional therapy has been limited; however, this trend is shifting, with low‐carbohydrate interventions becoming more widely accepted as evidenced by recent updates for health care providers from the American Diabetes Association Diabetes UK, Diabetes Australia and Canada. While there are many studies incorporating KDs in neurological disorders, 2 only a handful of studies to date have been tested in adults with sleep‐disordered breathing 3 . Reports often lack direct sleep assessment and report sleep quality questionnaires 4 .…”