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Effects of Diet on Immune System

The immune system’s primary role is to defend the body against disease and infection caused by fungi, bacteria, viruses, and parasites pathogenic organisms. Several factors, including nutrition, influence its function, and therefore, for best immunological outcomes, optimal nutrition is fundamental. The immune system acts in four different ways: It prevents microbes from entering the body and therefore acting as a barrier, it recognizes foreign invaders and recognizes if exposed again, distinguishing if they are harmful or not, they act on and destroy microbes identified as being harmful and lastly it generates immunological memory which enables its response to be more rapid and stronger if re-exposed to these harmful substances than it was for the original response (Venter et al.,2020). The human immune system’s many cell types, each with individual functional capabilities, help it achieve these complex and sophisticated actions. Like every other health aspect, a person’s diet influences their immune system. This research paper will give a better understanding of diet and nutrition’s role in maintaining immune function.

No individual diet or nutrient will boost the immune system as boosting refers to stimulation above a normal level; therefore, it is flawed to think that the immune system is boosted through diet. Proper diet acts to maintain and supports the already boosted immune system. The body’s nutrition can be achieved from an endogenous and exogenous source. Vitamins or micronutrients found from dietary intake activating immune functions are exogenous sources . Endogenous nutrients are instantaneous sources stored in the body cells and organs in the form of proteins, carbohydrates, proteins, and fats assimilated by the body during starvation or fasting. When exogenous nutrients are insufficient or absent, the body derives these sources through various mechanisms broken down for body use (Shao et al., 2021). The continuous energy supply needed by the immune system to function is obtained from carbohydrates. For the immune system to effectively clear pathogens, it must continuously remain active, and this active mode requires energy. Functional nutriments are nutritional elements beneficial for our body’s physiological and immune systems. Dietary factors that help in supporting or maintaining the immune system are either macro-nutrient elements (protein, fats, and carbohydrate) or micronutrient elements (minerals, water, and vitamins).

Innate and adaptive immune responses are the major subdivisions of the immune system. Innate immunity is the first line of defense from pathogens. Its mechanism of action is rapid and uses non-specific. It achieves its defense by using protective barriers such as skin and mucus to trap pathogens. This immunity is less effective, resulting from it not being specialized. Adaptive or acquired immunity is regulated by organs such as the spleen, bone marrow, lymph nodes, and thymus. It is pathogen-specific, thereby recognizing the specific pathogen and recalling it if re-exposed. The immune system’s response is noted by body inflammation (Childs and Miles, 2019). There exists a complex interconnection between the immune system and diet example; immune function is affected by nutrition impact on the microbiome, inflammatory process, white blood cell, and gut barrier function. It is not in diet quantity but the quality that sustains or supports the immune system. Diet and infection are a vicious cycle; Poor diets or malnutrition make one susceptible to infections, and vice versa, infection leads to malnutrition. An inappropriate or inadequate diet leads to lowered immunity. A lowered immunity leads to malabsorption, appetite loss, and nutrient diversion for immune response, which leads to nutrient loss, further damaging the defense mechanism.

There are specific roles for dietary components in maintaining and enhancing an effective immune system. Micronutrients such as iron, selenium, vitamin A, C, D and zinc have been identified for maintaining the effectiveness of the immune system. Vitamin A helps in the integrity of respiratory and gastrointestinal tract epithelium inhibiting infectious attacks and ensuring a proliferative response within the immune system by regulating cell division. Vitamin A maintains goblet cells’ presence in epithelial line coating. The mucus creates a barrier in the entry of diseases. The process of infection results in oxidative burden, vitamin C through non-specific mechanisms help release this burden. It accumulates in phagocytic cells, enhancing their phagocytic and chemotaxis role, ultimately killing microbes (Gombart and Maggini, 2020). Vitamin D is a key mediator of innate immune function, evidenced by increased vitamin D receptor expression in macrophages following a pathogenic attack. Its presence prevents the proliferation of B cells and immunoglobin secretion. Vitamin D is an essential component in the treatment of tuberculosis. Additionally, it shifts from Th1 to Th2 phenotype by suppressing T cell proliferation.

Selenium protects the cell against oxidative damage by lowering oxidative stress, reducing inflammation, and enhancing antibody levels in the blood. Selenium is mostly obtained from heart and aquatic products. Dietary sources are shellfish, dairy products, eggs, and whole grains. Neutrophils, during their attack on bacteria in the body, form highly toxic hydroxyl radicals. The myeloperoxidase activity necessary in this process is enhanced by iron. The immune system’s proliferative function is crucial in fighting infections. Cell division that allows for a proliferative response within the immune system is regulated by zinc.

The change in function of immune cells is influenced by the direct or indirect impact of nutrients. The more the quality of the diet is, the stronger the function of the immune system. Dietary provision of nutritional elements benefits immunity function and prevents overuse and side effects.


Childs, C. E., Calder, P. C., & Miles, E. A. (2019). Diet and immune function. Nutrients11(8), 1933.

Gombart, A. F., Pierre, A., & Maggini, S. (2020). A review of micronutrients and the immune system–working in harmony to reduce the risk of infection. Nutrients12(1), 236.

Shao, T., Verma, H. K., Pande, B., Costanzo, V., Ye, W., Cai, Y., & Bhaskar, L. V. K. S. (2021). Physical Activity and Nutritional Influence on Immune Function: An Important Strategy to Improve Immunity and Health Status. Frontiers in Physiology, 1702.

Venter, C., Eyerich, S., Sarin, T., & Klatt, K. C. (2020). Nutrition and the immune system: a complicated tango. Nutrients12(3), 818.


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