Diet and Inflammation

While there is evidence suggesting a positive correlation between immune-inflammatory signalling and mood symptoms, McNamara (2015) focuses his attention on long-chain omega-3 (LCn-3) fatty acids such as eicosapentaenic acid (EPA) and docosahexaenoic acid (DHA), which have anti-inflammatory properties. Mental disorders such as mood, bipolar, and major depressive disorder, are thought to be associated with low EPA and/or DHA biostatus, greater LCn-6: LCn-3 fatty acid ratio, and higher levels of various proinflammatory proteins. It is proposed that medications that reduce depressive symptoms or stabilize mood in manic depression disorder may be effective partly due to the reduction of immune-inflammatory signaling and augmented by anti-inflammatory medication. Furthermore, recent studies have implied that a higher LCn-6: LCn-3 fatty acid ratio may elevate risk of developing depression and feeling irritable. The author thus believes that increasing consumption of LCn-3 fatty acids may be a simple strategy to lessen the negative impact of increased immune-inflammatory signaling on mood stability. [NPIDs: insomnia, mood, omega-3s, EPA, DHA, inflammation, anti inflammatory, irritation, depression, sleep, sleep disorders]

This 2018 review looks at the importance of omega-3 polyunsaturated fatty acids (PUFAs) in the prevention and treatment of neuropsychiatric diseases, with a particular focus on depression and anxiety. Docosahexaenoic acid (DHA) is an example of an omega-3 PUFA that has been receiving attention for its relevance to many brain diseases. Moreover, Larrieu & Layé discuss the mechanisms in which these omega-3 PUFAs can modulate neurobiological processes involved in the pathophysiology of anxiety and depression. It is mentioned that high concentrations of polyunsaturated fatty acids are present in the brain, which may be explained by PUFA’s possibly protective or corrective role in this anatomical region. The authors debate on the involvement of the sensing activity of free fatty acid receptors, and the activity of the PUFA-derived endocannabinoid system and the hypothalamic-pituitary-adrenal axis. [NPIDs: insomnia, sleep, sleep disorders, PUFAs, omega-3s, depression, anxiety, DHA, HPA]

This 2021 study assessed a sample of Iranian adults on their food consumption to determine their food-based dietary inflammatory index (FDII). The aim was to investigate the relationship between the participants’ FDII and their risk of psychological disorders. The Iranian validated version of Hospital Anxiety and Depression Scale (HADS) and General Health Questionnaire (GHQ) were both used to examine psychological disorders. Results showed that people with the highest FDII scores (top quartile) had greater risks of depression, anxiety, and psychological distress, compared with those with the lowest FDII scores (lowest quartile). When this association between FDII scores and several mental health outcomes was further analyzed according to the subjects’ gender, food-based dietary inflammatory index scores were found to significantly correlate with increased incidences of depression, anxiety, and psychological distress among women. However, no significant link was identified when the highest and lowest quartiles for FDII scores were compared with one another in men. Nevertheless, Salari-Moghaddam et al. conclude that higher food-based dietary inflammatory index scores were related to greater prevalence of psychological disorders. [NPIDs: insomnia, sleep, sleep disorders, Iran, depression, anxiety, psychological distress, inflammation, inflammatory disorder]

In this 2019 study, Salari-Moghaddam et al. gathered the dietary inflammatory index (DII) scores of 3363 Iranian adult participants and checked whether they correlate with risk of psychological disorders. A food frequency questionnaire was initially distributed to obtain the participants’ dietary intakes, which was later used to calculate the dietary inflammatory index (DII). This index tells us how adherent the subjects were to the pro-inflammatory diet. The Iranian validated version of Hospital Anxiety and Depression Scale (HADS) and General Health Questionnaire (GHQ) were utilized for the psychological disorder assessment. Out of the whole sample, 22.6% scored 4 or more on either the HADS or GHQ, signifying presence of psychological distress. While 13.3% of the population had anxiety and 28% suffered from depression. Analysis models displayed the higher occurrence of depression, anxiety, and psychological distress in the individuals with the highest DII scores (highest quartile), compared with those in the lowest quartile. To summarize these findings, adherence to a pro-inflammatory diet was positively associated with odds of developing psychological disorders. [NPIDs: insomnia, sleep, sleep disorders, Iran, psychological disorders, inflammatory index, psychological distress, depression, anxiety, inflammation]

In this 2019 study, a mental health disorders profile score was calculated for each Iranian adult participant using regression analysis and based on their levels of anxiety, depression and psychological distress. Haghighatdoost et al. aimed to evaluate the relationship between the subjects’ dietary inflammatory index (DII) and the risk of a worsened mental health disorders profile. The DII scores were calculated based on consumption of 27 macro- and micro-nutrients, onions, teas, and caffeine, which were all obtained through the food frequency questionnaires. The results from the analysis models indicated that participants with the lowest dietary inflammatory index scores (lowest quartile) were less likely to be in the top tertile for mental health disorders profile. Similar relationships were found among both genders, but associations appeared to be more significant in men. The data suggests that the pro-inflammatory characteristics of the diet are directly associated with an increased risk of worse mental health disorder profiles. [NPIDs: insomnia, sleep, sleep disorders, Iran, anxiety, depression, psychological distress, inflammatory index, macros, macronutrients, micronutrients, onions, teas, caffeine]

Jahrami et al. (2019) aimed to back up findings of past studies by examining the association between dietary inflammation with schizophrenia among 240 participants in Bahrain. The sample included 120 patients recruited from psychiatric hospitals in Bahrain and another 120 healthy controls who were matched on age and sex. Food frequency questionnaires were administered to determine the energy-adjusted dietary inflammatory index (E-DII) of the subjects. The average score for the entire sample was 1.79, which is indicative of a general pro-inflammatory diet. People with schizophrenia seemed to have higher E-DII scores than the healthy controls. In fact, an increase in the E-DII score by 1 unit equated to an elevation in risk of schizophrenia by 62%. The difference between the controls and patients were more pronounced after the sample was organized by quartiles of E-DII scores. People with the most pro-inflammatory diets (highest quartile of E-DII) were almost 6 times more likely to have schizophrenia than those with the most anti-inflammatory diets (quartile 1). This is the first study to assess the link between DII and schizophrenia cases in a Middle Eastern population. The results suggest that a pro-inflammatory diet is related to schizophrenia. [NPIDs: insomnia, sleep, sleep disorders, inflammation, schizophrenia, Bahrain, inflammatory index, Middle East]

Ashton et al. (2020) examined a randomized controlled trial on the impact of several nutraceutical treatments on patients with bipolar depression. The 133 participants received 16 weeks adjunctive treatment of either placebo or N-acetylcysteine (alone or combined with mitochondrial-enhancing nutraceuticals). Four weeks after stopping the treatment, the subjects were assessed on diet (quality, inflammatory potential), body mass index, and other significant outcomes (depression symptoms, clinician-rated improvement, and functioning measures). Neither the Australian Recommended Food Score (measure of diet quality), dietary inflammatory index, nor body mass index scores could predict change in depression scores when comparing the combination treatment group with the placebo group. However, participants with better diet quality showed reduced general depression, bipolar disorder symptoms, and greater clinician-rated improvements, regardless of treatment and time. Moreover, a more anti-inflammatory diet (lower dietary inflammatory index score) was linked with less impairment in functioning. It was also suggested that the combination treatment of nutraceuticals may reduce the adverse effects of the pro-inflammatory diet on functioning. Furthermore, cohorts with lower BMIs who were given the combination therapy or N-acetylcysteine alone were reported to show better improvements by the clinicians. Although these results should be interpreted cautiously because of limitations, the data implies that there is an association between quality and inflammatory potential of diet, BMI, and the response to nutraceutical treatment for bipolar disorder in this clinical trial. [NPIDs: insomnia, sleep, sleep disorders, inflammation, depression, Australia, diet quality, bipolar, nutraceuticals, N-acetylcysteine]

Although the associations between dietary fiber intake with depression and inflammation are supported by several studies, Swann et al. (2020) state that the potential mechanisms behind these relationships are still poorly understood. This review therefore looks at the evidence on dietary fiber’s impact on depression and considers plausible mechanisms by which the fiber content of the diet is connected with depression. Possible explanations include the actions of microbiota - possibly modifying gene expression and increasing production of neurotransmitters. Inflammation is believed to mediate the interaction between dietary fiber consumption and depression. The author suspects that fiber-rich diets may lower inflammation by modifying both the pH and permeability of the gut. The result is a reduction in inflammatory compounds that may disrupt the concentration of neurotransmitters and ultimately reduce depressive symptoms. Yet, additional research is required to provide guidance on ways to enhance and prevent inflammatory and depressive disorders. [NPIDs: insomnia, sleep, sleep disorders, inflammation, depression, fiber, neurotransmitters, gut permeability]

While the previous study conducted by Noronha et al. reported the obesity-inducing potential of high-fat diets in rats (with elevated anxiety-related defensive behaviors and reactivity to stress), this present study published in 2019 induced obesity in rats and assessed their anxiety-related defensive behavioral responses. Also, their thermoregulatory responses to stress were tested through an open field assessment. Nine weeks of the fat-enriched diet induced obesity in the rats and increased their anxiety-related defensive behavioral responses and proinflammatory cytokine levels in several regions of their brain. Moreover, the rats’ tail skin temperature rose from the beginning and throughout the open field test. These results support the hypothesis that the high-fat diet induces neuroinflammation, heightens reactivity to stress, enhances anxiety-like defensive behavioral responses, and modifies excitability of brain nuclei that regulate neuroendocrine, autonomic, and behavioral responses to stressful stimuli. [NPIDs: insomnia, sleep, sleep disorders, obesity, stress, reactivity, anxiety, fat, neuroinflammation, behavior, neuroendocrine response]

Bonaccio et al. (2015) writes about the link between Mediterranean-like eating behavior with lower levels of inflammatory biomarkers, suggesting the anti-inflammatory action of Mediterranean-like foods. This review was focussed on the findings from the Moli-sani study, which addresses this connection between dietary habits and subclinical inflammation. The objective of the Moli-sani study was to investigate the genetic and environmental factors that either pose a risk or play protective roles in cardiovascular and tumor disease. Since it has been hypothesized that a diet abundant in healthy compounds could positively affect the production and clearance of platelets and white blood cells, the large-scale study assessed whether the Mediterranean diet determines the number of these inflammatory biomarkers in the subjects’ bodies. The Moli-sani study was an important cohort since it showed evidence of an association between a Mediterranean-like diet with lower levels of glucose, lipids, C-reactive protein (CRP), blood pressure, and 10-year cardiovascular risk. In addition, the intake of healthy foods rich in antioxidant vitamins and phytochemicals was found to correlate with lower blood pressure and CRP concentration in men. [NPIDs: insomnia, sleep, sleep disorders, Med diet, Mediterranean diet, inflammation, the Moli-sani study, cardiovascular disease, tumor disease, phytochemicals, antioxidants]

The aim of this 2017 study was to examine the relationship between the inflammatory potential of the diet and the presence of incident depressive symptoms, while also investigating the modulatory roles of sex, age, physical activity, and smoking status. Adjibade et al. recruited the 3523 participants of the SU.VI.MAX (Supplémentation en Vitamines et Minéraux Antioxydants) cohort, who were all initially free of depressive symptoms. Over an average follow-up period of 12.6 years, there were 172 reports of incident depressive symptoms. The dietary inflammatory index (DII), which measures the inflammatory potential of the diet, was not related to incident depressive symptoms among the sample population. However, DII was positively linked with risk of incident depressive symptoms in men. When the subjects were sorted by smoking status, current and former smokers with higher DII scores were also found to be more likely to show incident depressive symptoms. Finally, another meaningful relationship was identified between less physically active individuals and increased odds of depressive symptoms. To conclude, this study suggests that eating a healthy diet with anti-inflammatory properties might prevent signs of depression, especially among men, smokers, and physically inactive people. [NPIDs: insomnia, sleep, sleep disorders, inflammation, depression, smokers, physical activity]

Although there has been progress in the development of psychiatric therapy over the last few decades, Subramaniapillai et al. (2017) find that the efficacy of these treatments is limited. With the ongoing search for novel approaches, some have explored the idea of inflammation playing an influential role in mood disorder development. It has been identified that a large proportion of people with mood disorders are in pro-inflammatory environments. The aim of this review was to present the evidence showing the involvement of inflammation in various effector systems in mood disorders. The researchers looked at glutaminergic and immune system signaling, as well as metabolic parameters. The article examined infliximab for example as a target of the immune inflammatory system and a potential corrector of abnormal inflammatory social environments. [NPIDs: insomnia, sleep, sleep disorders, psychiatric therapy, inflammation, mood, pro-inflammatory environment, glutaminergic signaling, immunity, immune system]

Phillips et al. (2019) point out that there have been 480,000 references to inflammation by articles on diet and health in the National Library of Medicine database, in addition to 30,000+ peer-reviewed articles published on the relationship between diet, inflammation, and health outcomes. With this vast amount of evidence, it is now established that chronic systemic inflammation is associated with most non-communicable diseases (NCDs), including diabetes, obesity, cardiovascular disease, cancers, respiratory and musculoskeletal disorders. Since dietary constituents can influence the level of inflammation in a person, a dietary inflammatory index (DII) has been recently created to calculate the inflammatory potential of diet. While evidence linking this dietary inflammatory index with the risk of various NCDs has grown, this review aims to inspect the current state of research regarding DII’s relationship with cancers, neurodevelopment, mental health outcomes, as well as cardiometabolic, respiratory and musculoskeletal diseases. This article collected the findings of recent studies, discussed possible underlying mechanisms, and commented on future avenues of investigation in this field of nutritional research. [NPIDs: insomnia, sleep, sleep disorders, inflammation, non-communicable disease, diabetes, obesity, cardiovascular disease, cancer, respiratory disorders, musculoskeletal disorders, inflammatory index, cancer, neurodevelopment, cardiometabolic diseases, respiration, musculoskeletal]