Your immune system is hard at work protecting us against pathogens, and its energy must come from somewhere. Nutritional support must come in form of feeding cells of both innate and cell-mediated immunity and tolerogenic reactions towards non-threatening organisms, food components and even yourself.
Undernutrition weakens immune responses and heightens susceptibility to infection, decreasing overall immunity. Diets should contain the recommended amounts of micronutrients; however, supplements may be necessary in certain populations and situations that cannot always access a balanced, nutritious diet.
Vitamin C
Vitamin C is an indispensable nutrient with multiple uses in the body, playing an essential role in leukocyte functionality and immune regulation, including controlling production of pro-/anti-inflammatory cytokines and immunoglobulins (Igs).
Vitamin C helps improve epithelial barrier function and enhance phagocytic cell activity, and is required for biosynthesising certain collagens and glycoproteins, while acting as a cofactor in several enzymes that control production of reactive oxygen species, protecting cells against oxidative damage.
Vitamin C has been demonstrated to be antiviral in humans, increasing survival rate and attenuating excessive inflammation. Further clinical trials will need to be completed with definitive outcomes in order to establish whether dietary or pharmaceutical supplementation with high doses of Vitamin C prevents COVID-19 infection.
Vitamin D
Vitamin D is vital in supporting immune health and innate response in the body, binding to receptors on immune cells to induce them to produce antiviral and anti-inflammatory peptides which impede viral entry and limit inflammation.
Research studies conducted in vitro have demonstrated that 1,25(OH)2D can stimulate macrophages to release cathelicidins and defensins – natural antiviral peptides which strengthen innate immunity – as well as enhance their phagocytic ability and increase conversion of CD4 T cells into regulatory T (Treg) cells.
Studies have demonstrated that low vitamin D levels increase the risk of autoimmune diseases. Vitamin D can be found in foods like oily fish, eggs, mushrooms and full-fat dairy products and is essential to healthy skin and eye functioning. Furthermore, its production helps form mucus layers for digestion and respiratory systems that need protection.
Selenium
Selenium is an essential trace mineral found in Earth’s soil. Once in food sources such as plants and animals, animals ingest selenium through eating meats, seafood, fish shellfish nuts seeds whole grains vegetables as dietary sources for selenium consumption.
Animal studies demonstrate that mice lacking adequate levels of selenium exhibit less robust cell-mediated and humoral immune responses against viruses, tumors and allergens compared with their Se-adequate counterparts. Some human studies show selenium supplements enhance immunity; results depend on which immune response they target.
Human studies have suggested that selenium supplementation could mitigate some of the toxic side effects associated with chemotherapy drugs like cisplatin, an inorganic platinum-based chemotherapy drug used to treat cancers of the ovary, bladder, and lung. But these preliminary results need further confirmation before being accepted as true. Furthermore, chronically high intakes of selenium could result in seleniosis, with symptoms including brittle nails and hair; garlic breath; digestive upset; skin rashes; nausea; and diarrhea.
Zinc
Zinc is an essential trace mineral required for proper cell metabolism and an integral component of over 100 enzymes, playing an integral part in growth and development, cell division, immune responses and more. Zinc deficiency negatively impacts multiple aspects of immune responses such as phagocytosis, cell-mediated killing and cytokine production – which all are key aspects to their effective functioning.
Zinc-deficient children with sickle cell disease (SCD) tend to be shorter and weigh less than their age-matched peers, increasing the risk of infection, hospitalizations, and vaso-occlusive pain crises [3,48]. Supplemental zinc helps accelerate growth in these individuals while decreasing the frequency of these events [3,49].
Zinc ions have proven themselves highly effective at activating Th1 lymphocytes, which produce interferon g (IFN-g). IFN-g has proven its antiviral and antitumor properties; one study demonstrated this by showing serum levels of IL-2 and IFN-g reached their maximum concentration after only 16 h of exposure to zinc ions; normal concentrations typically take over 24 hours to reach this point.
Fatty Acids
Fatty acids are organic molecules composed of carbon chains with double bonds. They make up part of triglycerides, which store chemical energy needed for metabolism that requires oxygen. Fatty acids can also be taken up by cells for beta oxidation in the citric acid cycle before being burned off with oxygen to produce large amounts of ATP energy.
Studies demonstrate the impact of specific nutrients and diet patterns on immunity function. Unfortunately, our immune systems are complex systems, making it unlikely that any single food or nutrient would provide specific immunity-enhancing properties.
Diets rich in whole, nutrient-dense foods (such as fruits, vegetables, fish and legumes) that provide essential immune support are ideal. Furthermore, healthy lifestyle practices that emphasize sleep quality and stress management further boost immunity.