Diet and Chronic Pain

In this study by Strath et al. (2022), the authors explored whether dietary patterns are related to the risk of experiencing pain. Using data from the REGARDS study (n = 16061 participants, 44.6% males, 65 ± 9 years of age, 32.3% Black), participants were divided into categories depending on their dietary habits and the prominent food categories constituting their diets: convenience, plant-based, alcohol/salads, sweets/fats and ‘Southern’ (rich in fats, processed meat, organ meat, fried food, and sweetened drinks). Analysis of the results revealed that increased fidelity to ‘Southern’ diets was linked to a 41% increase in the relative risk (RR) of experiencing pain, while fidelity to a plant-based diet led to a 22% reduction in the RR of pain. The authors conclude that dietary patterns of poor quality raise the RR of pain, while a plant-based diet can lower the RR of pain, and recommend including dietary patterns as a part of a patient’s medical history. [NPID: Dietary pattern, nutrition, pain, racial differences]

Food intake patterns play critical roles in the regulation of overall health and well-being, however, the use of nutritional panels could protect from acute and chronic pain. Several dietary components, such as anti-inflammatory compounds and antioxidants, possess these protective properties. In addition, flavonoids, curcuminoids, terumbone (ginger root), taurine, and ω-3 polyunsaturated fatty acids were found to have analgesic and antinociceptive properties. Moreover, the prudent dietary intake of minerals and trace elements helps ameliorate inflammation and associated pain. Bjørklund et al. (2019) discuss these dietary components in their review, aiming to propose new dietary supplementation criteria targeted towards pain prevention. [NPID: Diet, natural compounds, nutritional supplementation, pain]

Current research demonstrates how pervasive chronic musculoskeletal pain can be, impacting individuals of different ages, genders, and ethnicities, in addition to how a plant-based diet (rich in vegetables, fruits, and whole grains) could help improve the symptoms of chronic pain and overall quality of life. In this study by Towery et al. (2018), the authors investigated the impact of a plant-based diet on symptoms of chronic musculoskeletal pain and associated functional impairments in a population of 14 participants over a period of eight weeks. The participants’ anthropometric measures were evaluated at the start of the intervention, together with submitting a Short Form Health Survey (SF-36) and a Numeric Pain Rating Scale (NPRS). Aided by a registered dietician, the participants were educated on plant-based diets and were provided with a sample menu cycle, in addition to using a phone app to document dietary intake and receive dietary support. Upon study conclusion, the participants repeated baseline measurements and submitted a Patient Global Impression of Change Scale. After highlighting their small sample size to be considered when appreciating their results, the authors observed an overall decrease in reported pain and an enhancement in the quality of life of the study participants, who reported an 89% fidelity to the dietary intervention. Thus, the authors conclude that a plant-based diet enhances the quality of life and symptoms experienced by individuals suffering from chronic musculoskeletal pain and that collaborations involving registered dieticians, physical therapists, and healthcare professionals should be established to integrate dietary interventions into patients’ treatment strategies. [NPID: Chronic musculoskeletal pain, complementary therapies, global health status, pain management, plant-based diet]

Despite the links between obesity and experiencing elevated levels of pain, our understanding regarding the impact of obesity and diet on postoperative pain remains insufficient. In this study by Song et al. (2018), the authors investigated the impact of obesity and diet by using the paw incision model (designed to investigate postoperative pain) in a population of Long-Evans rats, fed either a high-fat or a low-fat diet for a period of six weeks prior to the start of the experiment. The authors observed an increase in pain response and in the duration of overall hypersensitivity to pain upon conducting paw incisions in male rats receiving a high-fat diet compared to controls, however, female rats did not show the same propensities. Secondly, the authors noted that eliminating the high-fat diet for a period of two weeks prior to the paw incision procedure ameliorated the dietary derangement of pain behaviors despite the persistence of the weight gained. Moreover, the exposure to a high-fat diet for a short period of one week prior to the paw incision procedure led to an increase in observed pain behaviors, an impact that was noted to be of lesser magnitude compared to the six-week experimental exposure. From a cellular level, the authors noted an increase in lumbar dorsal root ganglion macrophage population and increased sensitivity of peritoneal macrophages to lipopolysaccharide with the administration of the high-fat diet for six weeks in male rats compared to controls. Finally, high-fat diet rats were noted to have higher skin levels of the nerve regeneration marker growth-associated protein 43 (GAP43) and retarded wound healing, compared to controls. The authors conclude that a high-fat diet worsens postoperative pain, especially in male rats, and that this dietary impact is not entirely associated with the weight gained, as short-term dietary exposure led to deranged pain responses that were not associated with significant obesity. [NPID: Postoperative pain, high fat diet, obesity, rats, animal]

In this randomized controlled trial by Buosi et al. (2021), the authors investigated the impact of a gluten-free diet (GFD) on improving chronic masticatory myofascial pain in a population of 39 women, who were divided into three groups (“healthy”, n = 14, age = 34.57 ± 9.14, “control”, n = 12, age = 31.50 ± 7.38, and “experimental”, n = 13, age = 30.00 ± 7.64) using the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD). The experimental group received a GFD for four weeks, and the treatment groups were evaluated at the start of the experiment and four weeks after its conclusion (save for the control group). Analysis of the results revealed a substantial decrease in pain intensity and a substantial increase in pressure pain thresholds of the anterior temporalis and masseter muscles with GFD intervention compared to controls. The authors comment on how GFD may be a beneficial adjunctive dietary intervention in women who suffer from TMD-associated chronic myofascial pain, and that more research is necessary to further our understanding of this relationship. [NPID: Chronic pain, mastication, myofascial, women, gluten free, dietary intervention]

Endometriosis is a chronic condition characterized by pain and inflammation originating from the presence of endometrial tissue outside of the uterine cavity. Scientific evidence points to the role of diet in ameliorating chronic inflammation, however, the evidence regarding the role diet plays in the perception of pain in endometriosis remains poorly understood. In this systematic review by Sverrisdóttir et al. (2022), the authors examine whether diet could influence pain perception in endometriosis patients. A comprehensive search was conducted on Medline and Embase to identify PRISMA and SWiM guidelines-adherent randomized controlled trials and observational studies, yielding six studies that fulfilled the inclusion criteria out of 2185 publications. The studies were assessed for bias using the Cochrane tool and the Newcastle-Ottawa scale and were found to be of low risk. Analysis of the studies revealed that a diet high in polyunsaturated fatty acids, a gluten-free diet, and a low nickel diet were associated with a substantial reduction in the perception of pain (five out of six studies, while all studies reported a positive improvement in pain perception). Meta-analysis was not possible due to significant heterogeneity between studies. The authors comment that, while all studies reported a positive influence of diet on pain perception in women suffering from endometriosis, the current evidence is mainly made up of non-randomized controlled trials with several areas of potential bias, which raises the demand for conducting more studies to fully understand the role diet may play in pain perception among women suffering from endometriosis. [NPID: Diet, dietary changes, dietary therapy, endometriosis, inflammation, inflammatory, pain, systematic review]

The influence of chronic pain disorders is not limited to somatic symptoms, but extends to causing behavioral alterations, as seen with anhedonia (i.e., loss of ability to feel pleasure) and observed reductions in motivation occurring alongside chronic pain. These behavioral alterations are postulated to occur due to cerebral limbic system dysfunction (responsible for regulating survival functions like eating), which would explain the concurrent obesity seen in chronic pain patients. The mechanisms governing the relationship between behavioral alterations, limbic dysfunction, and chronic pain are not well known to date. Thus, Lin et al. (2022) sought to investigate whether eating behavior is altered through the transition from low-back pain to chronic pain in some patients compared to others who recover from low-back pain, and whether the changes seen in the hedonic approach to fat-rich foods (i.e., the action of seeking fatty food, motivated by pleasure or by escapism from pain) seen in chronic pain patients is related to derangement in the nucleus accumbens (which is the cerebral juncture between motivation and behavior). The authors’ working hypothesis is that the nucleus accumbens, a central part of the limbic system, is responsible for the hedonic drive towards fat-rich food in patients suffering from pain, due to its function in survival behaviors. Thus, the authors conducted behavioral assays and structural brain imaging to investigate sub-acute back pain (SBP) patients and healthy controls, at the beginning of the study and at one year during follow-up, and acquired further data from chronic low-back pain patients (CLBP). The authors discovered that SBP patients who recovered from pain at the time of follow-up (SBPr) and CLBP patients displayed deranged dietary habits, compared to SBP patients who still had persistent back pain at follow-up (SBPp), who were found to display intact dietary habits. Through neurological examination, SBPp and CLBP patients displayed significant links between hedonic insight of fatty food and the volume of the nucleus accumbens, denoting that the alteration in nucleus accumbens seen in SBPp patients outlined in published literature might provide a protective effect from hedonistic behavioral derangements during the preliminary trajectory of the disease process. The authors thus conclude that disruptions seen in the eating behaviors occur after the disease course becomes chronic and that these disruptions are linked to alterations in the nucleus accumben’s structure. [NPID: Sub-acute back pain, chronic back pain, eating behavior, limbic dysfunction, hedonic perception]

Shafiee et al. (2021) recognize that repeated use of anti-inflammatory agents, the current treatment for inflammatory bowel disease (IBD), can have adverse effects on the patient. The aim of this review was to outline the current literature regarding the anti-inflammatory diet’s effectiveness in IBD. Recently, diet-related strategies have been formulated to try to improve the clinical activity scores in IBD patients. A promising approach is the modification of microbiota living in the digestive tracts through dietary therapy, which has been reported to improve IBD outcomes. The anti-inflammatory diet has been recommended as it restricts the consumption of carbohydrates that contain modified fatty acids. This diet also contains probiotics and prebiotics that can promote balanced intestinal microbiota composition. However, the authors emphasize that there is not yet clear evidence that supports this type of diet for the maintenance of remission or for prevention of IBD relapse. [NPID: pain, inflammation, IBD, digestion]

This 2021 review covers dietary nutrients that are capable of modifying glucose/lipid metabolism and insulin responses and aims to present the impacts of these nutrients on chronic inflammation and immunity. Katsimbri et al. also discuss how these nutritional regimens may act as potentially therapeutic tools for psoriasis and psoriatic arthritis. Dietary nutrients have been shown to activate the immune system, and their effects may result in the overproduction of proinflammatory cytokines. Psoriasis is a chronic, immune-mediated inflammatory disease that is more prevalent in obese individuals. It is said that weight loss interventions, supplementation, and various dietary regimens such as gluten-free and Mediterranean diet, may lead to improvements in psoriasis' natural course and response to therapy. Because of the low volume of research, further investigation into more sophisticated nutritional patterns, such as ketogenic, very low-carbohydrate or specific macro- and micro-nutrient substitution, are recommended. [NPID: pain, glucose, lipid metabolism, insulin, chronic inflammation, inflammation, immunity, psoriasis, psoriatic arthritis, proinflammatory cytokines, immune disease, gluten, Mediterranean diet, Med diet, keto, low-carb]

In this 2021 animal study, male DBA/1J mice were given a diet high in vitamin D3 (D3), and omega-3-fatty acids (O3FA) along with a highly bioavailable form of curcumin in a collagen-induced arthritis (CIA) murine model. The mice were challenged with bovine collagen II (CII) to induce arthritis. Joint thickness and standardized clinical score were checked regularly to determine the progress of disease in terms of severity. Hemshekhar et al. observed significantly drops in disease severity from curcumin administration alone (around 60%), while the mice eating the enriched diet plus curcumin supplements showed decreased disease severity by > 80% and maximally delayed disease onset and progression. It appeared that curcumin alone was responsible for mediating the suppression of anti-collagen antibodies and decreasing cellular infiltration and MMP abundance in the joints of the collagen-induced arthritis mice. But the daily curcumin supplementation in addition to the vitamin D3 and omega-3-fatty acids- enriched diet resulted in significantly more suppression of inflammatory biomarkers known to be associated with rheumatoid arthritis pathogenesis such as TNF, IFN-γ, and MCP-1. Since the combination of curcumin, vitamin D3 and omega-3-fatty acids have demonstrated their efficacy in delaying CIA severity and development in this animal model, it may be worthwhile assessing the use of these supplements in people at risk of developing rheumatoid arthritis in the future. [NPID: pain, vitamin D3, omega-3s, curcumin, animal, bovine collagen, joints, collagen, rheumatoid arthritis]

Costa et al. (2019) state that while there are studies on the role of nutritional interventions on migraine, there is a lack of research on how diet quality is associated with migraines. In this present intervention study, fifty-two women were given individualized diet meal plans based on their nutritional diagnosis. Their clinical and nutritional data were taken once a month for 90 days. 24-hour dietary recalls allowed the reporting of energy content and macronutrients, while the Brazilian Healthy Eating Index-Revised was used to assess diet quality. In addition, the participants’ migraine severity and depressive symptoms were examined. While the intervention did not appear to affect anthropometric characteristics, energy, macronutrients and fiber intake, there was a rise in diet quality assessment scores after 60 and 90 days of intervention. Furthermore, the subjects’ depression scores dropped after 60 days, and their Headache Impact Test scores decreased also after 90 days. The increase in BHEI-R score (diet quality measure) correlated with the decrease in Headache Impact Test scores (migraine severity) at the end of the intervention. Costa et al. declared diet quality enhancement as a good strategy for improving migraine severity, regardless of the nutritional status and weight change. [NPID: pain, migraine, macronutrients, fiber, diet quality]

This 2020 systematic review looks at the evidence linking dietary patterns, diet-related triggers, and dietary interventions with migraine. Dietary triggers are common causes of migraines, while specific diets have also been reported to reduce the frequency of migraine attacks. Hindiyeh et al. searched for randomized controlled trials and observational studies that assessed the effect of diet, food, and nutrition in people with migraine aged ≥18 years. Of the 43 studies included in this analysis, 11 evaluated dietary patterns, 12 investigated dietary interventions, and 20 examined diet-related triggers of migraines. Since the majority of the studies on dietary patterns and triggers were either cross-sectional studies or patient surveys, the overall quality of the studies were deemed to be of low quality. The review identified alcohol and caffeine consumption as the most common diet-related predictors of more frequent migraine attacks. Whereas, a lot of the interventions including low-fat and elimination diets, were linked with decreases in frequency of migraine attacks. The authors conclude that there is a lack of high-quality randomized controlled trial data on dietary patterns and triggers, while the number of randomized controlled trials on dietary interventions’ efficacy in migraine prevention is also limited. There is a need for further high-quality research on diet’s impact on migraine sufferers. [NPID: pain, migraine, migraine triggers, alcohol, caffeine, elimination diet, low-fat, migraine prevention]

This 2021 review covers dietary nutrients that are capable of modifying glucose/lipid metabolism and insulin responses and aims to present the impacts of these nutrients on chronic inflammation and immunity. Katsimbri et al. also discuss how these nutritional regimens may act as potentially therapeutic tools for psoriasis and psoriatic arthritis. Dietary nutrients have been shown to activate the immune system, and their effects may result in the overproduction of proinflammatory cytokines. Psoriasis is a chronic, immune-mediated inflammatory disease that is more prevalent in obese individuals. It is said that weight loss interventions, supplementation, and various dietary regimens such as gluten-free and Mediterranean diet, may lead to improvements in psoriasis' natural course and response to therapy. Because of the low volume of research, further investigation into more sophisticated nutritional patterns, such as ketogenic, very low-carbohydrate or specific macro- and micro-nutrient substitution, are recommended. [NPID: pain, insulin, inflammation, immunity, psoriasis, psoriatic arthritis, immunity, immune system, psoriasis obesity, keto, low-carb]

Since the Mediterranean diet has been promoted to possess positive effects on chronic diseases, Esposito et al. (2021) analyzed the lifestyle and dietary habits of Southern Italian patients with multiple sclerosis (MS), and examined the impact of the Mediterranean diet (MeDi) on multiple sclerosis clinical outcomes. The 435 participants had attended outpatient clinics for routine follow-up visits. During the experiment, the subjects were given a 29-item self-administered questionnaire on life and dietary habits. The results showed that 75.8% of the respondents were interested in nutrition, while 72.8% were non-smokers, 52.9% performed physical activity, and 45.6% used food supplements. People with multiple sclerosis and normal waist circumferences had higher Med Diet Scores (MDS), which is a measure of their adherence to the MeDi and also of their cardiovascular risk. Increased Med Diet Scores also correlated with lower MS Severity Score and Expanded Disability Status Scale. However, no relationship could be identified between the MDS and the total number of relapses. Metabolic comorbidities were associated with an increased 10-year cardiovascular risk. In conclusion, this data suggests that the Mediterranean diet has a positive impact on waist circumference, multiple sclerosis course and disability. Moreover, the MeDi appears to improve MS long-term disability outcomes. [NPID: pain, Mediterranean diet, Med diet, chronic disease, chronic pain, cardiovascular risk, multiple sclerosis]

Although a healthy diet has been associated with reducing symptoms of multiple sclerosis or slowing its progress, Evers et al. (2021) wanted to find out which diets specifically will lead to improvements in patients with multiple sclerosis (MS). The objective of this study was to analyze the relationship between diet quality, use of diets, and quality of life (QoL) in men and women with MS. Among the 623 women participants with MS, a correlation was discovered between diet quality with physical and mental quality of life (after adjusting for several confounders). There was a similar trend observed among the male sample (105 men). In addition, subjects who followed a specific diet had a higher diet quality and benefited from a higher quality of life, when compared with those who did not follow a particular diet. This study therefore found that people with MS, especially women, who adhered more to the Dutch dietary guidelines were more likely to have better outcomes such as physical and mental quality of life. Also, following an MS-specific diet may help to adhere to these guidelines. [NPID: pain, multiple sclerosis, MS, quality of life, QoL]

This narrative review published in 2020 outlines the current knowledge on the interaction between nutrition and chronic musculoskeletal pain, focusing on different underlying mechanisms such as inflammation, obesity, homeostatic balance, and central sensitization. Elma et al. also informs us how nutritional behavior interventions and dietary assessments can be utilized in clinical practice for patients with chronic musculoskeletal pain. Poor diet can be an underlying factor in chronic musculoskeletal pain and can often predict this type of pain. The current literature suggests that diet quality and dietary behavior can affect pain conditions, although the direction of this effect has not been confirmed. We require supplementary human nutrition studies that analyze specific musculoskeletal pain conditions and the underlying pathologies. [NPID: pain, chronic musculoskeletal pain, chronic pain, inflammation, obesity, homeostatic balance]

This 2018 review discusses the role of bioactive lipids in inflammation, acute and chronic pain, obesity and central nervous system diseases. These lipids are capable of modulating peripheral and central pathologic processes and have been linked with the gut microbiota through various mechanisms. A connection between the gut and the brain has been proposed (named the gut-brain axis) since microbial composition has been shown to influence behavior and cognition. Scientists have started investigating the relationship between this axis and health and disease, including stress-related (depression, anxiety and irritable bowel syndrome) and neurodevelopmental disorders (autism), and neurodegenerative diseases (Parkinson Disease, Alzheimer's Disease). Russo et al. mentions an animal study that discovered the reduction of abdominal pain in rats after systemic administration of bacteria. Other findings include PEA and butyrate, which reduced inflammatory markers in animal models with inflammatory bowel disease (IBD), and reduced inflammation as well as pain in irritable bowel syndrome and IBD, respectively. This review provides a summary of the relationship between inflammation, pain, microbiota and various lipids, focusing on N-acylethanolamines (NAEs) and short chain fatty acids (SCFAs) in the gut-brain axis and their functions in the central nervous system diseases. [NPID: pain, chronic pain, inflammation, obesity, gut-brain axis, IBS, anxiety, depression, neurodevelopmental disorders, autism, neurodegenerative diseases, Parkinson Disease, Alzheimer’s, animal, IBD]