Relationship between Omega-3 and Omega-6 Fatty Acid Intake and Chronic Obstructive Pulmonary Disease Morbidity

Distinguishing science from pseudoscience in commercial respiratory interventions: an evidence-based guide for health and exercise professionals

Respiratory function has become a global health priority. Not only is chronic respiratory disease a leading cause of worldwide morbidity and mortality, but the COVID-19 pandemic has heightened attention on respiratory health and the means of enhancing it. Subsequently, and inevitably, the respiratory system has become a target of the multi-trillion-dollar health and wellness industry. Numerous commercial, respiratory-related interventions are now coupled to therapeutic and/or ergogenic claims that vary in their plausibility: from the reasonable to the absurd. Moreover, legitimate and illegitimate claims are often conflated in a wellness space that lacks regulation. The abundance of interventions, the range of potential therapeutic targets in the respiratory system, and the wealth of research that varies in quality, all confound the ability for health and exercise professionals to make informed risk-to-benefit assessments with their patients and clients. This review focuses on numerous commercial interventions that purport to improve respiratory health, including nasal dilators, nasal breathing, and systematized breathing interventions (such as pursed-lips breathing), respiratory muscle training, canned oxygen, nutritional supplements, and inhaled L-menthol. For each intervention we describe the premise, examine the plausibility, and systematically contrast commercial claims against the published literature. The overarching aim is to assist health and exercise professionals to distinguish science from pseudoscience and make pragmatic and safe risk-to-benefit decisions.

Acetate-encapsulated Linolenic Acid Liposomes Reduce SARS-CoV-2 and RSV Infection

Emergent Coronaviridae viruses, such as SARS-CoV-1 in 2003, MERS-CoV in 2012, and SARS-CoV-2 (CoV-2) in 2019, have caused millions of deaths. These viruses have added to the existing respiratory infection burden along with respiratory syncytial virus (RSV) and influenza. There are limited therapies for respiratory viruses, with broad-spectrum treatment remaining an unmet need. Since gut fermentation of fiber produces short-chain fatty acids (SCFA) with antiviral potential, developing a fatty acid-based broad-spectrum antiviral was investigated. Molecular docking of fatty acids showed α-linolenic acid (ALA) is likely to interact with CoV-2-S, NL63-CoV-S, and RSV-F, and an ALA-containing liposome interacted with CoV-2 directly, degrading the particle. Furthermore, a combination of ALA and a SCFA-acetate synergistically inhibited CoV2-N expression and significantly reduced viral plaque formation and IL-6 and IL-1β transcript expression in Calu-3 cells, while increasing the expression of IFN-β. A similar effect was also observed in RSV-infected A549 cells. Moreover, mice infected with a murine-adapted SARS-CoV-2 (MA10) and treated with an ALA-liposome encapsulating acetate showed significant reductions in plaque-forming units present in lung tissue and in infection-associated lung inflammation and cytokines. Taken together, these results demonstrate that the ALA liposome-encapsulating acetate can be a promising broad antiviral therapy against respiratory infections.

Lipid-Sensing Receptor FFAR4 Modulates Pulmonary Epithelial Homeostasis following Immunogenic Exposures Independently of the FFAR4 Ligand Docosahexaenoic Acid (DHA)

The role of pulmonary free fatty acid receptor 4 (FFAR4) is not fully elucidated and we aimed to clarify the impact of FFAR4 on the pulmonary immune response and return to homeostasis. We employed a known high-risk human pulmonary immunogenic exposure to extracts of dust from swine confinement facilities (DE). WT and Ffar4-null mice were repetitively exposed to DE via intranasal instillation and supplemented with docosahexaenoic acid (DHA) by oral gavage. We sought to understand if previous findings of DHA-mediated attenuation of the DE-induced inflammatory response are FFAR4-dependent. We identified that DHA mediates anti-inflammatory effects independent of FFAR4 expression, and that DE-exposed mice lacking FFAR4 had reduced immune cells in the airways, epithelial dysplasia, and impaired pulmonary barrier integrity. Analysis of transcripts using an immunology gene expression panel revealed a role for FFAR4 in lungs related to innate immune initiation of inflammation, cytoprotection, and immune cell migration. Ultimately, the presence of FFAR4 in the lung may regulate cell survival and repair following immune injury, suggestive of potential therapeutic directions for pulmonary disease.

Habitual fish oil supplementation and incident chronic obstructive pulmonary disease: Data from a prospective cohort study

BACKGROUND

Fish oil is one of the most popular supplements in the UK and other developed countries. However, the relationship between fish oil use and chronic obstructive pulmonary disease (COPD) is unclear.

OBJECTIVE

To prospectively examine the association of habitual fish oil supplementation with incident COPD risk and to evaluate potential effect modification by genetic predisposition.

METHODS

This study included 484,414 participants (mean and standard deviation [SD] age: 56.5 [8.1] years) from the UK Biobank who completed a touchscreen questionnaire on habitual fish oil supplement use between 2006 and 2010 and were followed up through 2018. Cox regression models were used to estimate the hazard ratios (HRs) and 95% confidence intervals (95% CIs) with adjustment for sociodemographic and lifestyle behaviours, health conditions, and other potential confounding factors. A weighted genetic risk score (GRS) for COPD was derived from 112 validated single nucleotide polymorphisms.

RESULTS

During a median follow-up of 9.0 years, 8860 incident COPD events were recorded. A total of 31.4% (152,230) of the study participants reported habitual fish oil supplementation at baseline. Habitual fish oil supplementation was significantly associated with a lower risk of incident COPD (adjusted HR: 0.88; 95% CI: 0.84-0.93). The association with COPD did not differ by GRS strata (P for interaction = 0.880). The results from subgroup and sensitivity analyses supported the robustness of our findings.

CONCLUSIONS

Our findings suggest that habitual fish oil supplementation is associated with a lower risk of incident COPD, irrespective of genetic predisposition.

Ambient ozone effects on respiratory outcomes among smokers modified by neighborhood poverty: An analysis of SPIROMICS AIR

BACKGROUND

Neighborhood poverty has been associated with poor health outcomes. Previous studies have also identified adverse respiratory effects of long-term ambient ozone. Factors associated with neighborhood poverty may accentuate the adverse impact of ozone on respiratory health.

OBJECTIVES

To evaluate whether neighborhood poverty modifies the association between ambient ozone exposure and respiratory morbidity including symptoms, exacerbation risk, and radiologic parameters, among participants of the SPIROMICS AIR cohort study.

METHODS

Spatiotemporal models incorporating cohort-specific monitoring estimated 10-year average outdoor ozone concentrations at participants' homes. Adjusted regression models were used to determine the association of ozone exposure with respiratory outcomes, accounting for demographic factors, education, individual income, body mass index (BMI), and study site. Neighborhood poverty rate was defined by percentage of families living below federal poverty level per census tract. Interaction terms for neighborhood poverty rate with ozone were included in covariate-adjusted models to evaluate for effect modification.

RESULTS

1874 participants were included in the analysis, with mean (± SD) age 64 (± 8.8) years and FEV₁ (forced expiratory volume in one second) 74.7% (±25.8) predicted. Participants resided in neighborhoods with mean poverty rate of 9.9% (±10.3) of families below the federal poverty level and mean 10-year ambient ozone concentration of 24.7 (±5.2) ppb. There was an interaction between neighborhood poverty rate and ozone concentration for numerous respiratory outcomes, including COPD Assessment Test score, modified Medical Research Council Dyspnea Scale, six-minute walk test, and odds of COPD exacerbation in the year prior to enrollment, such that adverse effects of ozone were greater among participants in higher poverty neighborhoods.

CONCLUSION

Individuals with COPD in high poverty neighborhoods have higher susceptibility to adverse respiratory effects of ambient ozone exposure, after adjusting for individual factors. These findings highlight the interaction between exposures associated with poverty and their effect on respiratory health.

A biological rationale for the disparate effects of omega-3 fatty acids on cardiovascular disease outcomes

The omega-3 fatty acids (n3-FAs) eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) rapidly incorporate into cell membranes where they modulate signal transduction pathways, lipid raft formation, and cholesterol distribution. Membrane n3-FAs also form specialized pro-resolving mediators and other intracellular oxylipins that modulate inflammatory pathways, including T-cell differentiation and gene expression. Cardiovascular (CV) trials have shown that EPA, administered as icosapent ethyl (IPE), reduces composite CV events, along with plaque volume, in statin-treated, high-risk patients. Mixed EPA/DHA regimens have not shown these benefits, perhaps as the result of differences in formulation, dosage, or potential counter-regulatory actions of DHA. Indeed, EPA and DHA have distinct, tissue-specific effects on membrane structural organization and cell function. This review summarizes: (1) results of clinical outcome and imaging trials using n3-FA formulations; (2) membrane interactions of n3-FAs; (3) effects of n3-FAs on membrane oxidative stress and cholesterol crystalline domain formation during hyperglycemia; (4) n3-FA effects on endothelial function; (5) role of n3-FA-generated metabolites in inflammation; and (6) ongoing and future clinical investigations exploring treatment targets for n3-FAs, including COVID-19.

N-3 PUFAs and their specialized pro-resolving lipid mediators on airway inflammatory response: beneficial effects in the prevention and treatment of respiratory diseases

Respiratory diseases include a wide range of pathologies with different clinical manifestations, affecting the normal airways and lung function. An increase in the inflammatory response is considered a characteristic hallmark of these diseases, being also a critical factor for their progression. The n-3 polyunsaturated fatty acids (n-3 PUFAs) eicosapentaenoic acid (C20:4n-3, EPA), docosahexaenoic acid (C22:6n-3, DHA) and their lipid mediators are known to have an inflammation pro-resolution effect. The effects of these n-3 PUFAs in the prevention and treatment of respiratory diseases are beginning to be understood. Consequently, this article aims to analyze the influence of n-3 PUFAs and their lipid mediators on the inflammatory response in respiratory health, emphasizing recent data concerning their beneficial effects in the prevention and possible treatment of different respiratory diseases, particularly asthma, airway allergic syndromes and chronic obstructive pulmonary disease. The review includes studies regarding the effects of EPA, DHA, and their specialized pro-resolving lipid mediators (SPMs) on in vivo and in vitro models of respiratory disease, concluding that EPA and DHA have a positive impact in attenuating the pro-inflammatory response in respiratory diseases, reducing symptoms like nasal congestion, fever and difficulty in breathing. Controversial data reported are probably due to differences in several factors, including the dosages, administration vehicles, and the supplementation times employed, which are aspects that remain to be addressed in future studies.

Inhalation of nebulized omega-3 fatty acids mitigate LPS-induced acute lung inflammation in rats: Implications for treatment of COPD and COVID-19

Many current treatment options for lung inflammation and thrombosis come with unwanted side effects. The natural omega-3 fatty acids (O3FA) are generally anti-inflammatory and antithrombotic. O3FA are always administered orally and occasionally by intravenous (IV) infusion. The main goal of this study is to determine if O3FA administered by inhalation of a nebulized formulation mitigates LPS-induced acute lung inflammation in male Wistar rats. Inflammation was triggered by intraperitoneal injection of LPS once a day for 14 days. One hour post-injection, rats received nebulized treatments consisting of egg lecithin emulsified O3, Budesonide and Montelukast, and blends of O3 and Melatonin or Montelukast or Cannabidiol; O3 was in the form of free fatty acids for all groups except one group with ethyl esters. Lung histology and cytokines were determined in n = 3 rats per group at day 8 and day 15. All groups had alveolar histiocytosis severity scores half or less than that of the disease control (Cd) treated with LPS and saline only inhalation. IL-6, TNF-α, TGF-β, and IL-10 were attenuated in all O3FA groups. IL-1β was attenuated in most but not all O3 groups. O3 administered as ethyl ester was overall most effective in mitigating LPS effects. No evidence of lipid pneumonia or other chronic distress was observed. These preclinical data suggest that O3FA formulations should be further investigated as treatments in lung inflammation and thrombosis related lung disorders, including asthma, chronic obstructive pulmonary disease, lung cancer and acute respiratory distress such as COVID-19.

Assessment of Polyunsaturated Fatty Acids on COVID-19-Associated Risk Reduction

Pooled evidence conveys the association between polyunsaturated fatty acids and infectious disease. SARS-CoV-2, an enveloped mRNA virus, was also reported to interact with polyunsaturated fatty acids. The present review explores the possible mode of action, immunology, and consequences of these polyunsaturated fatty acids during the viral infection. Polyunsaturated fatty acids control protein complex formation in lipid rafts associated with the function of two SARS-CoV-2 entry gateways: angiotensin-converting enzyme-2 and cellular protease transmembrane protease serine-2. Therefore, the viral entry can be mitigated by modulating polyunsaturated fatty acids contents in the body. α-Linolenic acid is the precursor of two clinically important eicosanoids eicosapentaenoic acid and docosahexaenoic acid, the members of ω-3 fats. Resolvins, protectins, and maresins derived from docosahexaenoic acid suppress inflammation and augment phagocytosis that lessens microbial loads. Prostaglandins of 3 series, leukotrienes of 5 series, and thromboxane A₃ from eicosapentaenoic acid exhibit anti-inflammatory, vasodilatory, and platelet anti-aggregatory effects that may also contribute to the control of pre-existing pulmonary and cardiac diseases. In contrast, ω-6 linoleic acid-derived arachidonic acid increases the prostaglandin G₂, lipoxins A₄ and B₄, and thromboxane A₂. These cytokines are pro-inflammatory and enhance the immune response but aggravate the COVID-19 severity. Therefore, the rational intake of ω-3-enriched foods or supplements might lessen the complications in COVID-19 and might be a preventive measure.

Graphic Abstract

Impact of diet and the bacterial microbiome on the mucous barrier and immune disorders

The prevalence of chronic immune and metabolic disorders is increasing rapidly. In particular, inflammatory bowel diseases, obesity, diabetes, asthma and chronic obstructive pulmonary disease have become major healthcare and economic burdens worldwide. Recent advances in microbiome research have led to significant discoveries of associative links between alterations in the microbiome and health, as well as these chronic supposedly noncommunicable, immune/metabolic disorders. Importantly, the interplay between diet, microbiome and the mucous barrier in these diseases has gained significant attention. Diet modulates the mucous barrier via alterations in gut microbiota, resulting in either disease onset/exacerbation due to a "poor" diet or protection against disease with a "healthy" diet. In addition, many mucosa-associated disorders possess a specific gut microbiome fingerprint associated with the composition of the mucous barrier, which is further influenced by host-microbiome and inter-microbial interactions, dietary choices, microbe immigration and antimicrobials. Our review focuses on the interactions of diet (macronutrients and micronutrients), gut microbiota and mucous barriers (gastrointestinal and respiratory tract) and their importance in the onset and/or progression of major immune/metabolic disorders. We also highlight the key mechanisms that could be targeted therapeutically to prevent and/or treat these disorders.

Associations of ω-3 Fatty Acids With Interstitial Lung Disease and Lung Imaging Abnormalities Among Adults

Docosahexaenoic acid (DHA), an ω-3 polyunsaturated fatty acid, attenuates interstitial lung disease (ILD) in experimental models, but human studies are lacking. We examined associations of circulating levels of DHA and other polyunsaturated fatty acids with hospitalization and death due to ILD over 12 years in the Multi-Ethnic Study of Atherosclerosis (MESA; n = 6,573). We examined cross-sectional associations with CT lung abnormalities in MESA (2000-2012; n = 6,541), the Framingham Heart Study (2005-2011; n = 3,917), and the Age, Gene/Environment Susceptibility-Reykjavik Study (AGES-Reykjavik) (2002-2006; n = 1,106). Polyunsaturated fatty acid levels were determined from fasting blood samples and extracted from plasma phospholipids (MESA and AGES-Reykjavik) or red blood cell membranes (Framingham Heart Study). Higher DHA levels were associated with a lower risk of hospitalization due to ILD (per standard-deviation increment, adjusted rate ratio = 0.69, 95% confidence interval (CI): 0.48, 0.99) and a lower rate of death due to ILD (per standard-deviation increment, adjusted hazard ratio = 0.68, 95% CI: 0.47, 0.98). Higher DHA was associated with fewer interstitial lung abnormalities on computed tomography (per natural log increment, pooled adjusted odds ratio = 0.65, 95% CI: 0.46, 0.91). Higher DHA levels were associated with a lower risk of hospitalization and death due to ILD and fewer lung abnormalities on computed tomography in a meta-analysis of data from population-based cohort studies.