The novel coronavirus (COVID-19) has put a spotlight on the critical role of nutrition in supporting immune health. The World Health Organization (WHO) reports that “while no foods or dietary supplements can prevent or cure COVID-19 infection, healthy diets are important for supporting immune systems”.¹ According to the Centers for Disease Control and Prevention (CDC), people with weakened immune systems are at greater risk for serious complications from the virus and may have it for a longer period of time than those with stronger immune systems. While a strong immune system may not prevent certain viruses, eating an adequate amount of nutrients as part of a varied diet is essential for the health and function of all cells, including immune cells. Overall, good nutrition is vital for health, especially when the immune system needs the strength to fight back.
Types of Immunity
In understanding how nutrition plays a role in immunity, it’s important to recognize that the cells of the immune system are divided into two types of immune responses: innate and adaptive. The innate (natural) immune response is the first response to an invading pathogen. The innate immune system is comprised of anatomical barriers to infection, including skin, the acidity of stomach secretions, and normal microflora of the gastrointestinal tract. Furthermore, it’s comprised of soluble factors and phagocytic cells that form the first line of defense against pathogens. The adaptive (active) immune response serves as the second line of defense against immunity and is more complex than the innate response as it involves antigen-specific responses and has the ability to specifically recognize a pathogen and ‘remember’ it if exposed to it again. Adaptive immunity is developed when individuals are exposed to diseases or when they are immunized against them with vaccines. Components of both innate and adaptive immunity interact and work synergistically to protect the body from infection and disease.
The Impact of Malnutrition
Nutrition is a critical determinant of the immune response, and malnutrition has been long understood to impair immune function. While malnutrition is often suggested to be related to undernutrition, it encompasses overnutrition, as well. The extent of impairment is dependent upon the severity of the deficiency, consideration to nutrient interactions, the presence of infection, and age. Research suggests that nutrients may directly or indirectly impact immune cells causing changes in their function or may exert effects via changes in the gut microbiome.²
While maintaining adequate nutrition is vital, there are specific nutrients that are essential for immunocompetence, namely vitamins A, C, D, E, B6, and B12, folic acid, iron, selenium, and zinc. Micronutrient deficiencies can predispose an individual to certain infections, and immune function may be improved by restoring deficient micronutrients to recommended levels, which can increase resistance to infection and support recovery. However, it should be noted that while poor nutrition can compromise immune function and increase infection risk, excessive nutrient intake of some micronutrients, such as iron, may impair the immune system. With inadequate nutrient intake, diet alone may be insufficient and tailored micronutrient supplementation based on specific age-related needs necessary.³
Specific Nutrients to Support the Immune-Response
Protein: Protein is vital to build and repair tissues in the body. You need protein to create antibodies and cells that attack infections. If you don’t consume enough protein, you’ll manufacture fewer white blood cells to combat antigens and your immune system won’t operate at full strength.
Vitamin C: Vitamin C is a potent antioxidant that supports the immune system by stimulating the activity of white blood cells which help to protect the body against infection.
Vitamin D: Vitamin D supports the function of immune cells that protect your body against pathogens.
Zinc: Zinc is an essential micronutrient that’s needed for normal development and functioning of immune cells. It also supports wound healing.
Iron: Iron supports the immune system by stimulating the production of white blood cells that combat pathogens and prevent infection.
Vitamin B6: Vitamin B6 is essential in the formation of healthy red blood cells and aids in maintaining the lymphatic system; a network of tissues and organs which helps protect the body from infection and disease.
Vitamin B12: Vitamin B12 supports white blood cell activity which are essential for proper immune system functioning.
Vitamin E: Vitamin E is an important antioxidant that protects cells from damage and supports a healthy inflammatory response.
Vitamin A: Vitamin A helps regulate the immune system and protects against infections by keeping skin and tissues in the mouth, stomach, intestines and respiratory system healthy.
Folate/Folic Acid: Folate/Folic Acid helps create and repair cells’ DNA in the body and plays an important role in the healthy balance of the immune system.
Selenium: Selenium is an important antioxidant that helps combat oxidative stress, which reduces inflammation and supports immune function.
Probiotics: Probiotics can influence the activity of our own immune cells, regulating inflammation, barrier function, and cell-to-cell signaling. A robust population of beneficial bacteria can help crowd out harmful bacteria.
For more information on how nutrition and other factors can support immunity, check out these resources on our website and let’s support better health, together!
¹ Healthy at Home. Retrieved October 7, 2020, from https://www.who.int/campaigns/connecting-the-world-to-combat-coronavirus
² Childs, C. E., et al., Nutrients. 2019; 11(8): 1933, doi: 10.3390/nu11081933
³ Maggini, S., et al., Nutrients. 2018; 10(10): 1531, doi: 10.3390/nu10101531