Our immune system is a sophisticated defence mechanism that relies on the harmonious interaction of cells, molecules, tissues, and organs to ensure the body’s protection and optimal performance.
For optimal performance, the immune system must possess the ability to differentiate between what belongs to the body and what does not. This entails the capability to distinguish between harmful non-self molecules like invading viruses and bacteria and non-threatening non-self molecules like those encountered in our food consumption.
The Role of a Wholefood Diet
Nutrition plays an essential role in the regulation of immunological responses and the function of immune cells. In order to support the immune system through dietary choices, it is advisable to incorporate a wide selection of fruits and vegetables, wholegrains, nuts and seeds, and protein derived from sources such as meat, seafood, and legumes.
The consumption of a varied selection of wholefoods is essential for providing your body and immune system with a wide spectrum of vital nutrients, including vitamins, minerals, healthy fats, and proteins, necessary for the proper functioning of all cells in our body.
Consuming diets that consist predominantly of processed, packaged, and refined sugary foods often lack essential nutrients. These types of diets often result in heightened inflammation throughout the body, an imbalance in the gut’s good and bad bacteria, and a disrupted immune system. Additionally, continuously following highly restrictive diets can cause deficiencies in vital nutrients.
Maintaining a Healthy Diet Seasonally
Generally, during the winter months, we experience an increased number of infections from colds and flu, mainly from spending more time indoors and in closer proximity to other people. Once we become infected with a virus or bacterial pathogen, our immune system becomes activated, which further increases the demand for energy and nutrients, especially when we experience a fever.
Maintaining adequate nutrition levels while battling an infection enables immune cells to function efficiently and swiftly. One way to achieve this is by adhering to a whole-food diet and opting for fresh, locally available, and seasonal ingredients.
Specific Nutrients for Healthy Immune Function
Certain vitamins and minerals that are essential to support the development, growth and function of immune cells include:
Vitamin C supports the increase in blood levels of antibodies, which the body needs to fight off infections, and helps differentiate white blood cells, enabling the body to determine the required type of immune protection.
Food sources include green leafy vegetables, broccoli, capsicums, citrus fruits, tomatoes, berries, and kiwi fruit.
Vitamin D helps to support the functioning of the innate immune system, which is our first line of defence. Research has also shown that Vitamin D exhibits antibacterial activity within specific immune cells, providing protection against invading bacteria.
Food sources include fatty fish such as salmon, sardines, mackerel, sundried mushrooms and cod liver oil.
Vitamin A is a potent antioxidant and supports the immune system by helping antibodies respond to invading pathogens more effectively.
Food sources include beef liver, sweet potato, carrot, capsicum, pumpkin, spinach, mangoes and apricots.
Zinc is required for supporting immune responses, especially immune cell development and communication. It plays an important role in regulating the inflammatory response of the immune system when we become infected and acts as an antioxidant. Research has shown that a mild zinc deficiency has been associated with an imbalance in the functioning of both the adaptive and innate immune response and a greater risk of infections.
Food sources include seafood (especially oysters), beef, pork, chicken, legumes, seeds, nuts, eggs and whole grains.
Selenium is a potent antioxidant that can help reduce inflammation, specifically within the respiratory tract. A diet deficient in selenium may result in impaired immune responses and an increased susceptibility to infections.
Food sources include seafood, organ meats and nuts such as Brazil nuts.
The Importance of Hydration
Research has shown that our immune cells function better when we are adequately hydrated. The mucous membranes in our mouth need plenty of water to produce salivary immunoglobulin A, which is one of the first lines of defence against invading bacteria and viruses. Dehydration has been linked with poorer functioning of immune cells, specifically neutrophils, a type of white blood cell that helps to fight infection. Being properly hydrated also helps to deliver nutrients and oxygen to your cells.
Aim to keep well hydrated, especially in the winter months when you might not feel as thirsty. Herbal teas and bone broths can be incorporated to help maintain optimal hydration. How much water you should be drinking can be variable depending on exercise levels, weight, if you’re pregnant or breastfeeding, however aiming for at least 2 – 2.5 litres a day is a good start.
References:
- Childs CE, Calder PC, Miles EA. Diet and immune function. Nutrients. 2019 Aug 16;11(8):1933.
- Noor S, Piscopo S, Gasmi A. Nutrients Interaction with the Immune System. Archives of Razi Institute. 2021 Dec;76(6):1579.
- Tourkochristou E, Triantos C, Mouzaki A. The influence of nutritional factors on immunological outcomes. Frontiers in Immunology. 2021 May 31;12:665968.
- Mourtzoukou EG, Falagas ME. Exposure to cold and respiratory tract infections. The International Journal of Tuberculosis and Lung Disease. 2007 Sep 1;11(9):938-43.
- Carr AC, Maggini S. Vitamin C and immune function. Nutrients. 2017 Nov 3;9(11):1211.
- Aranow C. Vitamin D and the immune system. Journal of investigative medicine. 2011 Aug;59(6):881-6.
- Huang Z, Liu Y, Qi G, Brand D, Zheng SG. Role of vitamin A in the immune system. Journal of clinical medicine. 2018 Sep 6;7(9):258.
- Prasad AS. Zinc in human health: effect of zinc on immune cells. Molecular medicine. 2008 May;14(5):353-7.
- Huang Z, Rose AH, Hoffmann PR. The role of selenium in inflammation and immunity: from molecular mechanisms to therapeutic opportunities. Antioxidants & redox signaling. 2012 Apr 1;16(7):705-43..
- Fortes MB, Diment BC, Di Felice U, Walsh NP. Dehydration decreases saliva antimicrobial proteins important for mucosal immunity. Applied Physiology, Nutrition, and Metabolism. 2012 Oct;37(5):850-9.
- Chishaki T, Umeda T, Takahashi I, Matsuzaka M, Iwane K, Matsumoto H, Ishibashi G, Ueno Y, Kashiwa N, Nakaji S. Effects of dehydration on immune functions after a judo practice session. Luminescence. 2013 Mar;28(2):114-20.
- Better Health Channel. Water – a vital nutrient [Internet]. Melbourne: Department of Health, State Government of Victoria; 2021 November 9.