Regulation of immune function in healthy adults: one-stop guide on the role of dietary fatty acids, gut microbiota-derived short chain fatty acids, and select micronutrients in combination with physical activity.

The immune system requires an adequate supply of nutrients, although current dietary recommendations may not account for optimal immune function in healthy adults. Nutrient inadequacies due to the growing influence of the western diet pose a risk for immune dysfunction. This review aims to determine the beneficial effects of supplementing dietary fats, nutrients that modulate gut microbiota, and specific micronutrients on systemic immune functions (concentrations of plasma cytokines, antibodies, and acute phase proteins) during health and acute inflammatory conditions, including COVID-19. We discussed micronutrients (selenium, zinc, and vitamin D) with compelling evidence supporting immunomodulatory properties. Additionally, the synergistic effects of physical activity and dietary interventions on systemic immune markers are explored. Briefly, evidence suggests that dietary consumption of monounsaturated (oleic and palmitoleic acids) and omega-3 polyunsaturated fatty acids (eicosapentaenoic and docosahexaenoic acids) promotes anti-inflammatory properties. Food sources (fiber, prebiotics, probiotics, omega-3) and patterns (Mediterranean diet) increase the production of short-chain fatty acids, beneficially altering gut microbiota composition, which subsequently enhances the immunomodulatory properties of circulating immune cells. A positive synergistic role of nutrient supplementation (omega-3 and fiber) and physical activity on circulating C-reactive protein and interleukin-6 levels has been observed. Lastly, omega-3 supplementation during COVID-19 infection may reduce circulating C-reactive protein and pro-inflammatory cytokines and improves pain and fatigue symptoms. This review highlights recent findings that support the beneficial role of specific nutrients in promoting systemic immune function in healthy adults. However, to establish specific dietary recommendations to support optimal immune function, more research is required. Key takeaway: Increasing dietary fats (fish and olive oils) and specific micronutrients may positively impact systemic immune function in healthy adults. Evidence suggests that these nutrients promote immunomodulatory properties useful in resolving acute infection.

Nutrition and immunity: perspectives on key issues and next steps.

In January 2022, a group of experts came together to discuss current perspectives and future directions in nutritional immunology as part of a symposium organized by the Canadian Nutrition Society. Objectives included (1) creating an understanding of the complex interplay between diet and the immune system from infants through to older adults, (2) illustrating the role of micronutrients that are vital to the immune system, (3) learning about current research comparing the impact of various dietary patterns and novel approaches to reduce inflammation, autoimmune conditions, allergies, and infections, and (4) discussing select dietary recommendations aimed at improving disease-specific immune function. The aims of this review are to summarize the symposium and to identify key areas of research that require additional exploration to better understand the dynamic relationship between nutrition and immune function.

Impact of Cesarean Delivery and Breastfeeding on Secretory Immunoglobulin A in the Infant Gut Is Mediated by Gut Microbiota and Metabolites.

How gut immunity in early life is shaped by birth in relation to delivery mode, intrapartum antibiotic prophylaxis (IAP) and labor remains undetermined. We aimed to address this gap with a study of secretory Immunoglobulin A (SIgA) in the infant gut that also tested SIgA-stimulating pathways mediated by gut microbiota and metabolites. Among 1017 Canadian full-term infants, gut microbiota of fecal samples collected at 3 and 12 months were profiled using 16S rRNA sequencing; C. difficile was quantified by qPCR; fecal metabolites and SIgA levels were measured by NMR and SIgA enzyme-linked immunosorbent assay, respectively. We assessed the putative causal relationships from birth events to gut microbiota and metabolites, and ultimately to SIgA, in statistical sequential mediation models, adjusted for maternal gravida status in 551 infants. As birth mode influences the ability to breastfeed, the statistical mediating role of breastfeeding status and milk metabolites was also evaluated. Relative to vaginal birth without maternal IAP, cesarean section (CS) after labor was associated with reduced infant gut SIgA levels at 3 months (6.27 vs. 4.85 mg/g feces, p < 0.05); this association was sequentially mediated through gut microbiota and metabolites of microbial or milk origin. Mediating gut microbiota included Enterobacteriaceae, C. difficile, and Streptococcus. The milk or microbial metabolites in CS-SIgA mediating pathways were galactose, fucose, GABA, choline, lactate, pyruvate and 1,2-propanediol. This cohort study documented the impact of birth on infant gut mucosal SIgA. It is the first to characterize gut microbe-metabolite mediated pathways for early-life SIgA maturation, pathways that require experimental verification.

Cross-Sectional Study Protocol for the COVID-19 Impact Survey of Mothers and Their 7-11 Year Old Children in Alberta, Canada.

Objectives: Our aim is to understand the effect of the COVID-19 pandemic on families who have been followed longitudinally in two cohorts studied in Alberta, Canada. We will examine household infections during the COVID-19 pandemic, financial impact, domestic violence, substance use, child school and daily life and relationships in the home. We will identify risk and protective factors for maternal mental health outcomes using longitudinal data that can inform policy and government resource allocation in future disasters. Methods: Mothers who are currently participating in two longitudinal studies, Alberta Pregnancy Outcomes and Nutrition (APrON; N = 1,800) and All Our Families (AOF: N = 2,534) were eligible to participate. Mothers were invited to complete the baseline COVID-19 Impact Survey (20-30 min) within 4 months of March 15, 2020, which was when the province of Alberta, Canada, implemented school closures and physical-distancing measures to prevent the spread of COVID-19. Mothers were asked to report on their own, their child's and their family's functioning. Mothers were re-surveyed at 6 months after completion of the initial COVID-19 Impact Survey, and will be re-surveyed again at 12 months. Results: Responses from participants in both cohorts will be examined in harmonized analyses as well as separately. Descriptive, multivariable analysis will be undertaken to examine risk and resiliency over time and factors that predict mental health and well-being. Conclusions: This study will provide timely information on the impact of COVID-19 for Albertan families. It will identify risk and protective factors for mental health and well-being among contemporary urban families supported by a publicly funded health care system to inform allocation of resources to support those most vulnerable during a global pandemic.