Your immune system has the innate ability to fight infections. However, the optimal functioning of your immune system relies on how well you take care of your body and mind beginning from childhood to your senior years. There are key nutrients, lifestyle and dietary factors that play an important role in your overall immune health. Vitamin C and vitamin D both help your immune cells detect and fight viruses while getting adequate rest and eating a clean diet that is low in refined carbohydrates is also a necessity for immune function. Other nutrients to consider during cold and flu season include medicinal mushrooms and oil of oregano.
The human body has an incredible ability to filter out and protect against most microbial infections. However, in order for the immune system to function at its highest potential, several dietary and lifestyle changes, as well as supplementation, may increase the ability of the immune system to protect against both bacterial and viral infections.
A healthy diet can make a positive impact on immune function. To optimize immune function, you should try to limit the intake of large amounts of sugar and simple carbohydrates, which rapidly turn to sugar in the blood stream. Simple carbohydrates include foods such as bagels, cereals and white breads. Spikes in your blood sugar levels can hinder the immune response and increase your susceptibility to infection.1
On the other hand, foods that are rich in antioxidants such as broccoli, spinach, carrots, avocados, beets, squash and sweet potato can aid in the immune response.2 Antioxidants activate the special immune cells involved in the immune cascade, prevent damage to immune cells and protect against the harmful effect of excess production of reactive oxygen species.2
Reactive oxygen species are oxygen molecules that damage your healthy cells.
The ability to manage stress is a key skill to practice in order to optimize immune function.
The impact that stress has on immune function was demonstrated in a study in which 276 healthy volunteers had their stress hormone levels tested at the beginning of the study before they were exposed to the virus that causes the common cold.3 The volunteers were then quarantined and monitored for the next 5 days. They were assessed for the viral load as well as symptoms of the common cold. The researchers found that the participants who had exposure to a long-term threatening stressful experience demonstrated increased stress hormones at the beginning of the study and this increase in stress hormones put them at higher risk of developing the virus which led to the display of more cold symptoms.3 Throughout the lifespan, beginning in early childhood to late adulthood, environmental and situational stressors can negatively affect your immune system. Therefore, managing stress through meditation, deep breathing, yoga and exercise can be beneficial in both limiting the negative impacts of stress response but also supporting the immune function throughout the lifespan.
Good quality sleep is another key component of immune health. When you sleep, cytokines, which are proteins used to help the body fight of infection, are produced.4 When released, these proteins signal an immune cascade of cells needed to help fight off infection.4 Without proper sleep, less cytokines are produced and there is an increased risk of infection.4 Sleep needs are different for everyone, however on average, approximately 8 hours of quality sleep each night is recommended.
Exercise can be both helpful and a hinderance for a healthy immune response. Regular, moderate exercise can be protective and enhance immune function.5 Moderate exercise includes going for a brisk walk or jog, yoga, weight lifting, hiking, swimming or playing a sport. However, prolonged periods of intense exercise can actually depress immunity, especially without adequate recovery time.6 Therefore, it’s important to manage the expectations of your body. If you’ve had a long week at work and are feeling run-down, it might be best to select a yoga class instead of a high intensity workout.
During times of increased or prolonged stress, the immune response can be supported with specific herbs and supplements.
Vitamin C is a well-known antioxidant nutrient which plays an important role in immune function for all ages. A diet rich in fruits and vegetables can supply most individuals with the proper amount needed to fight of infection. However, many people in North America do not have an adequate intake of fruits in vegetables in their diet to reach these levels of vitamin C.7 This includes young children and teens who may be picky eaters or struggle to consume adequate amounts of fruits and vegetables. For this population, a vitamin C supplement may be helpful. Adults can also benefit from taking a vitamin C supplement; however, adults may need a higher dose, to help support immune function.
Vitamin D is involved in the immune response and individuals who are deficient in vitamin D are at a greater risk for infections.8 In Canada, 24% of the population ages 6 to 11 and 29% of people between age 12 to 19 are deficient in the sunshine vitamin,8 making it one of the most common nutrient deficiencies for children.9 Individuals at any age who are not eating a large amount of vitamin D rich foods or who have minimal sun exposure, may benefit from supplementing with vitamin D at a dose appropriate for their age. It is best to have this nutrient tested regularly due to the prevalence of deficiency and vital role that it plays in the body.
Mushrooms are gaining popularity as important supplements in part, due to their beta-glucan content. Beta-glucans are special polysaccharides found in the cell walls of mushrooms and yeasts.10 Glucans are part of a group of biologically active natural molecules with immune-stimulating function.10 Commonly used mushrooms include: Chaga, Reishi, Lion’s Mane, Cordyceps, Turkey Tail, and Maitake. These mushrooms can be made into a tea, powder form or ingested as capsules. Mushrooms have adaptive qualities which means that when taken regularly, they can help the body to manage stress.11 Therefore, mushrooms may be useful for adults who find themselves struggling to manage stress while supporting overall immune function and energy.
Oil of oregano is a potent oil extracted from the leaves of the oregano plant. Taken as a supplement, it typically used when dealing with common cold symptoms.12 In research, this plant extract also works as a natural antifungal and antimicrobial both topically and internally.13 It is available in both a liquid and capsule form. A 2019 study tested the use of oregano along with thyme on several different viruses12. Although not effective against all viruses, the oil demonstrated strong antiviral activity against the rhinovirus which is the cold virus, and most of the influenza strains.12
Although infections cannot always be controlled or prevented, with certain lifestyle modifications, a healthy diet and a combination of the right immune-supporting supplements, you can hopefully feel more at ease heading into the fall season.
- Jafar N, Edriss H, Nugent K. The effect of short-term hyperglycemia on the innate immune system. The American journal of the medical sciences. 2016 Feb 1;351(2):201-11.
- A Puertollano M, Puertollano E, Alvarez de Cienfuegos G, A de Pablo M. Dietary antioxidants: immunity and host defense. Current topics in medicinal chemistry. 2011 Jul 1;11(14):1752-66.
- Cohen S, Janicki-Deverts D, Doyle WJ, Miller GE, Frank E, Rabin BS, Turner RB. Chronic stress, glucocorticoid receptor resistance, inflammation, and disease risk. Proceedings of the National Academy of Sciences. 2012 Apr 17;109(16):5995-9.
- Irwin MR. Sleep and inflammation: partners in sickness and in health. Nature Reviews Immunology. 2019 Nov;19(11):702-15.
- Simpson RJ, Kunz H, Agha N, Graff R. Exercise and the regulation of immune functions. Progress in molecular biology and translational science. 2015 Jan 1;135:355-80.
- Gleeson M. Effects of exercise on immune function. Sports Science Exchange. 2015;28(151):1-6.
- Vanherwegen AS, Gysemans C, Mathieu C. Regulation of immune function by vitamin D and its use in diseases of immunity. Endocrinology and Metabolism Clinics. 2017 Dec 1;46(4):1061-94.
- Haimi M, Lerner A. Nutritional deficiencies in the pediatric age group in a multicultural developed country, Israel. World Journal of Clinical Cases: WJCC. 2014 May 16;2(5):120.
- Akramienė D, Kondrotas A, Didžiapetrienė J, Kėvelaitis E. Effects of ß-glucans on the immune system. Medicina. 2007 Aug;43(8):597.
- Rossi P, Buonocore D, Altobelli E, Brandalise F, Cesaroni V, Iozzi D, Savino E, Marzatico F. Improving training condition assessment in endurance cyclists: effects of Ganoderma lucidum and Ophiocordyceps sinensis dietary supplementation. Evidence-Based Complementary and Alternative Medicine. 2014 Apr 1;2014.
- Tseliou M, Pirintsos SA, Lionis C, Castanas E, Sourvinos G. Antiviral effect of an essential oil combination derived from three aromatic plants (Coridothymus capitatus (L.) Rchb. f., Origanum dictamnus L. and Salvia fruticosa Mill.) against viruses causing infections of the upper respiratory tract. Journal of Herbal Medicine. 2019 Sep 1;17:100288.
- Wijesundara, N. M., Lee, S. F., Cheng, Z., Davidson, R., & Rupasinghe, H. P. (2021). Carvacrol exhibits rapid bactericidal activity against streptococcus pyogenes through cell membrane damage. Scientific Reports, 11(1). https://doi.org/10.1038/s41598-020-79713-0