Nutritional immunology is field of immunology that focuses on studying the influence of nutrition on the immune system and its protective functions. This special area of immunology also involves studying possible effects of diet on prevention and managing development of diseases such as autoimmune diseases, allergy, cancer and infectious diseases. Other related topics of nutritional immunology are: malnutrition, malabsorption and nutritional metabolic disorders including the determination of their immune products.
The Role of Nutrition and Diet in Diseases
Autoimmune diseases
Causes of development and progression of many autoimmune diseases are generally unknown. The "Western pattern diet" consists of high-fat, high-sugar, low-fiber meals with surfeit of salt and highly processed food, which have pro-inflammatory effects and may promote Th1 and Th17 - biased immunity, release of pro-inflammatory mediators and alter monocyte and neutrophil migration from bone marrow. The impact of diet is studied in relation to these autoimmune diseases:
Number of people who suffer from food allergies has risen over the past decades. Again, there are many factors and theories, why the prevalence is increasing, e.g. the hygiene hypothesis. Nutrition can help as a prevention of development food allergies, especially early food intake. Breastfeeding is considered to be the main aid how to prevent food allergies due to milk constitution and properties, such as oligosaccharides, secretory IgA, vitamins, antioxidants and possible transfer of microbiota.
Cancer
is disease with multifactorial roots. Nutrition and diet also have indirect influence of induction of this illness, however, it's mostly associated to unhealthy lifestyle, cigarette smoking and alcohol drinking.
Nutrients with Positive Effect
Polyphenols
s are organic chemicals which naturally occur in plants. They are important antioxidants with anti-inflammatory properties. It was demonstrated that curcumin can modulate immunity in many ways, mainly via regulation and inhibition transcription factors such as nuclear factor NF-kB and activator protein 1. Another polyphenol, resveratrol modulates and promotes immune response.
and docosahexaenoic acid are omega-3 fatty acids, which can be found in seafood, primarily in salmon, tuna, mackerel, herring and sardines and in fish oil. These two fatty acids are important components of cell membranes. It has been shown that they have anti-inflammatory effect in the body. EPA and DHA inhibit production of pro-inflammatory cytokines such as IL-1β, TNF-α, IL-6; decrease expression of adhesion molecules which are involving in inflammation and may modulate and decrease production of prostaglandins and leukotriens from the n-6 fatty acid arachidonic acid. These changes are most likely caused by alterations in lipid rafts on cell membranes that has effect on signaling cascades and inhibition of activation of the pro-inflammatory transcriptional factor NF-κB. EPA and DHA can increase production of anti-inflammatory cytokine IL-10 and promote production of protective mediators such as resolvins, protectins and maresins.
Prebiotics and probiotics
Dietary prebiotics are defined according to International Scientific Association of Probiotics and Prebiotics as “a selectively fermented ingredient that results in specific changes in the composition and/or activity of the gastrointestinal microbiota, thus conferring benefit upon host health”. Prebiotics involve mainly oligosaccharides carbohydrates. They can modulate immune responses in gut through many mechanisms, directly or indirectly. One of the regulation is happening via regulation of growth of beneficial microbial organisms in intestine. Energy source requirements varies among different bacterial population, therefore specific food components may induce increase of specific bacteria and their anaerobic fermentation of prebiotics produces mainly short chain fatty acids. Butyrates can reduce macrophage and neutrophil recruitment and can inhibit NF-κB signaling pathway. SCFAs can also modulate immune system directly, e.g. via interaction with carbohydrates receptors on immune cells Definition of probiotics by the Food and Agriculture Organization of the United Nation and World health Organization is: “…live microorganisms which when administered in adequate amounts confer a health benefit on the host”. Probiotics and their metabolites are balancing and modulating anti-inflammatory or pro-inflammatory immune responses in gut, therefore they are important for preservation of equilibrium in the intestine. Mechanisms of the modulation are varied, for example: competing with pathogen organisms for nutrients, attachment and space thus maintaining intestinal barrier, inducement of antimicrobial peptides such as β-defensin-2, they increase of T regulatory cells, down/up-regulation of cytokines and chemokines, they can affect polarization of the immune response, icrease the production of IgA in gut and many more. Most commonly used bacteria populations as probiotics belong to Lactobacillus, Enterococcus, Bifidobacterium group
