Ingestion, Immunity, and Infection: Nutrition and Viral Respiratory Tract Infections

Abstract

Respiratory infections place a heavy burden on the health care system, particularly in the winter months. Individuals with a vulnerable immune system, such as very young children and the elderly, and those with an immune deficiency, are at increased risk of contracting a respiratory infection. Most respiratory infections are relatively mild and affect the upper respiratory tract only, but other infections can be more serious. These can lead to pneumonia and be life-threatening in vulnerable groups. Rather than focus entirely on treating the symptoms of infectious disease, optimizing immune responsiveness to the pathogens causing these infections may help steer towards a more favorable outcome. Nutrition may have a role in such prevention through different immune supporting mechanisms. Nutrition contributes to the normal functioning of the immune system, with various nutrients acting as energy sources and building blocks during the immune response. Many micronutrients (vitamins and minerals) act as regulators of molecular responses of immune cells to infection. It is well described that chronic undernutrition as well as specific micronutrient deficiencies impair many aspects of the immune response and make individuals more susceptible to infectious diseases, especially in the respiratory and gastrointestinal tracts. In addition, other dietary components such as proteins, pre-, pro- and synbiotics, and also animal- and plant-derived bioactive components can further support the immune system. Both the innate and adaptive defense systems contribute to active antiviral respiratory tract immunity. The initial response to viral airway infections is through recognition by the innate immune system of viral components leading to activation of adaptive immune cells in the form of cytotoxic T cells, the production of neutralizing antibodies and the induction of memory T and B cell responses. The aim of this review is to describe the effects of a range different dietary components on anti-infective innate as well as adaptive immune responses and to propose mechanisms by which they may interact with the immune system in the respiratory tract.

Effects of Dietary Supplementation with Carrot-Derived Rhamnogalacturonan-I (cRG-I) on Accelerated Protective Immune Responses and Quality of Life in Healthy Volunteers Challenged with Rhinovirus in a Randomized Trial

“…These results indicate that dietary supplementation with cRG-I does not lead to broad, non-specific activation of the innate immune system, but rather enhances its responsiveness during immune challenges such as a viral infection. These and earlier findings support the notion that dietary intake of 0.3 g/d cRG-I leads to some form of priming or training of the innate immune system, and this altered responsiveness to an immune challenge can be observed in ex vivo NK cell activity and CXCL-10 production in the blood compartment and locally in the respiratory tract [ 3 , 7 , 11 ]. A limitation of this study is that NK cell and phagocytic activity were not measured after the RV16 challenge.…”

“…While certain vitamins (A, B6, B12, folate, C, D and E) and minerals (zinc, copper, selenium, and iron) contribute to the normal function of the immune system [ 1 , 2 ], other food components and especially certain fibers can play an important role in educating and regulating immune cell responsiveness. Everything we ingest is sampled by immune cells in the Waldeyer’s ring in the nasopharynx, in Peyer’s patches in the small intestine and by dendritic cells protruding through the intestinal epithelial layer [ 3 ]. The responsiveness of macrophages and dendritic cells (DC) that sense molecular patterns on microorganisms, but also on food components, via pattern recognition receptors (PRR) can be modulated and is known as immune training or priming.…”

“…Moreover, changes in composition of the gut microbiota and production of bioactive metabolites such as short chain fatty acids (SCFA) can also modify immune responsiveness [ 4 ]. Given that macrophages and DCs from the intestine can recirculate via lymph and blood to other mucosal areas such as the respiratory tract, alterations in immune responsiveness due to effects in the gut can increase responsiveness to, e.g., airway infections [ 3 ].…”

Evaluation of nutritional status in lung transplant recipients and its correlation with post-transplant short-term prognosis: a retrospective study

“…Additionally, the drainage volume 24 hours after surgery, hospitalization duration and total costs of the recipients with nutritional risk were significantly increased, which may be because malnourished patients experience a decline in immune function. Plasma protein levels can reflect the nutritional status of the body's visceral proteins (26,27). Albumin and prealbumin, which are synthesized in the liver, serve as important indicators in the assessment of nutritional status (28,29).…”

Association between levels of blood trace minerals and periodontitis among United States adults

“…The glutathione peroxidase system is the most widely studied, which uses the selenium of its active site to detoxify ROS, such as hydrogen peroxide and phospholipid hydrogen peroxide. Similarly, selenium regulates the activity of transcription factors (nuclear factor-kappa B and activator protein-1) and the expression of related genes ( 41 ). Selenium even reduces levels of tumor necrosis factor-α and cyclooxygenase-2 produced by macrophages in response to endotoxins and down-regulates the expression of adhesion molecules.…”