Nutrition care is an important part of the prevention and treatment of respiratory illness. Proper nutrient intake may lower the likelihood of respiratory infections and can cut the severity and length of illness.
The role of vitamin D in health is well recognized. It supports the immune system against infection by upregulating defensins and cathelicidins; antimicrobial proteins secreted by immune cells (1). These proteins have anti-bacterial, anti-viral, and anti-fungal properties. Vitamin D deficiency is also associated with increased susceptibility to infections and more severe respiratory illness.
The body’s primary source of vitamin D enters through the skin, which synthesizes it in response to sunlight. Dietary sources include milk, fortified juices, fatty fish like salmon, eggs, and mushrooms. Supplementation may be recommended when a deficiency is present and is typically below 4,000 IU (international units), the upper limit for adults. Always consult your doctor or dietitian before supplementing high levels of vitamin D.
Omega-3 Fatty Acids
Omega-3 fatty acids include Eicosapentaenoic acid (EPA), Docosahexaenoic acids (DHA), and alpha-linolenic acids (ALA). Omega-3’s have been found to control inflammation throughout the body by affecting cells involved in the inflammatory response and the production of inflammatory mediators (3). EPA and DHA also used to create lipid mediators known as resolvins, which control inflammation by blocking the production of pro-inflammatory mediators.
Omega-3 fatty acids are considered essential because the body cannot make them and must be acquired through diet. Dietary sources of EPA and DHA include fatty fish like salmon, tuna, mackerel, and sardines. ALA is commonly found in nuts, seeds, and vegetable oils. Many foods such as cereals, eggs, milk, yogurt, and juices are also fortified with omega-3s.
Vitamin C is a powerful antioxidant that works throughout the whole body. It protects organs and tissues from oxidative damage and supports immune cells (like neutrophils) in fighting disease. It also recycles vitamin E and its antioxidant properties. The immune system uses more vitamin C during illness, cases of scurvy (caused a vitamin C deficiency) have even been reported after severe respiratory illness (2).
Vitamin C is needed to repair damaged lining and supports the epithelium in its barrier function against invaders. This is because vitamin C enhances collagen synthesis, an integral protein of the lining, and protects it against oxidative damage from toxins. It enhances proliferation and differentiation of B- and T- lymphocytes as well as antibody levels.
Vitamin C is commonly found in produce such as citrus fruits and broccoli. The body has a poor storage ability for vitamin C and so it must be consumed continuously through diet. While many vitamin C supplements exist, it is always best to get it from plant food sources that offer countless other benefits and phytonutrients.
While vitamin C, vitamin D, and omega-3 fatty acids offer health benefits, these are not miracle workers. Their ability to support health and prevent illness is very much dependent on a well-balanced diet that offers adequate amounts of macro- and micronutrients. It is always best to get nutrients from real food sources and not just supplements. It is good practice to take adequate amounts of these nutrients continuously as part of a healthy diet and not just mega-dose when the risk for illness increases. Mega-dosing can be dangerous, it is always good practice to consult your doctor or dietitian before supplementing on a specific nutrient.
- Berthon, B. S., & Wood, L. G. (2015, March 5). Nutrition and respiratory health–feature review. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4377870/
- Carr, C., A., & Silvia. (2017, November 3). Vitamin C and Immune Function. Retrieved from https://www.mdpi.com/2072-6643/9/11/1211
- Calder, P. C. (2010, March). Omega-3 fatty acids and inflammatory processes. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3257651/