How to Optimize Your Immune System

NewsGuard 100/100 Score

The immune system is a central difference in the protection against pathogenic organisms. Several factors influence the strength of the immune system; some of these factors are not capable of being modified, such as genetics and stage of life, but several modifiable factors can influence the immune system. By optimizing each of these modifiable factors, the immune system can be optimized for function.

Immune System

Image Credit:

What are the modifiable factors affecting the immune system?

Several risk factors are capable of being modified by individuals to ensure that their immune system is optimized for function. The following represent the most salient factors that can be modified:

  • Alcohol consumption: alcohol can suppress a wide range of immune responses, including disrupting communication between the gut microbiome and the intestinal immune system. Alcohol also damages the epithelial cell barrier, compromises T cell and neutrophil function, therefore disrupting the gut barrier function. These effects are also seen in acute binge drinking. Therefore, moderate alcohol consumption can optimize immune response
  • Smoking status: cigarettes contain several compounds which act as pro-inflammatory and immunosuppressive agents; these include nicotine, formaldehyde, carbon monoxide, tar, benzopyrene, acetone, cadmium, nitrogen oxides, ammonia, and hydroxyquinone. Nicotine in particular results in a decreased phagocytotic activity of neutrophils, in addition to inhibiting homing, and the release of reactive oxygen species, therefore compromising neutrophil activity. Overall, the inflammatory agents compound tissue destruction on further release of inflammatory agents that can lead to chronic inflammatory syndrome. Therefore, smoking cessation is the best way to optimize immunity.
  • Stress
  • Diet: this includes total nutrient intake (macro and micronutrient)
  • Level of exercise, physical fitness, and body fat percentage

The factors that cannot be modified include age, illness, infection and infection history, genetics, vaccination status, got to microbiota profile, frailty, time of day, and stage of the life course (i.e., pregnancy status, menopause, etc.)

The effect of obesity on immunity

The competence of the immune system can be diminished as a consequence of being overweight or obese. This effect occurs because of the reduced activity of helper T cells, cytotoxic T cells, B cells, and natural killer cells.

Moreover, there is reduced antibody and interferon-gamma production. Consequently, those with obesity are increasingly susceptible to a range of pathogenic infections relative to healthy-weight individuals and demonstrate poor responses to vaccination.

An example of this effect was seen during the 2009 H1N1 influenza A pandemic; obese individuals demonstrated weakened and delayed antiviral responses to the infection. Obese individuals also recovered poorly relative to healthy weight counterparts. Studies in both animals and humans have demonstrated an increased period of viral shedding, indicating impaired viral control and targeting.

Studies have demonstrated the number of activated, interferon-gamma producing, and granzyme expressing cytotoxic T cells are reduced in obese individuals relative to healthy individuals. Moreover, obesity is correlated with increased inflammatory mediators, indicating an underlying state of chronic low-grade inflammation. Subsequently, those with obesity are predisposed to contracting chronic conditions.

Ensuring that body fat percentage is kept within a healthy range through the maintenance of a healthy weight. This can be aided in part by maintaining a healthy diet, exercising regularly, and getting adequate sleep.

The importance of diet on the immune system

Nutrition plays a central role in optimizing immune system function. A balanced diet provides:

  • Energy for the cells in the immune system to function
  • Material for the production of RNA, DNA, and protein production (receptive, acute phase proteins, antibodies, cytokines, etc.) and new immune cells
  • Factors capable of regulating the immune cell metabolism (i.e., Vitamin A and zinc)
  • Nutrients with antibacterial or antiviral capabilities (i.e., vitamin D and zinc)
  • Oxidative and inflammatory stress regulators (e.g., vitamin C, vitamin E, selenium, zinc, omega 3 fatty acids, selenium, and plant polyphenols)
  • Fuel for the intestinal microbiota which can modulate the immune system

In the absence of a nutritionally balanced diet, the immune system is not provided with adequate quantities of nutrients to function optimally. Subsequently, individuals with poor diets are at increased susceptibility to infection and demonstrate a poor ability to control infection. The following table outlines the effects of micronutrients on different aspects of immunity:


Role in barrier function

Role in the cellular aspect of innate immunity

Role in T cell-mediated immunity

Role in B cell-mediated immunity

Vitamin A

Promotes epithelial cell differentiation and homing of B and T cells

Supports activity of macrophages is and regulates the number and function of natural killer cells

Regulate the development and differentiation of Th1 and Th2 cells as well as the conversion of naive T cells into regulatory T cells; regulates interleukin (IL)-2 IFN-γ and TNF production

Immunoglobulin production and the support of  cell function

Vitamin B6

Promotes the homing of T cells to the gut

Supports activity of the natural killer cells

Enhances differentiation of T cells; promotes IL-2 production

Aids antibody production

Vitamin B9

Acts as a survival factor for regulatory T cells when they enter the gut

Supports activity of the natural killer cells

Promotes expansion of T cells and enhances the Th1 response

Aids antibody production

Vitamin B12

A cofactor for microbiota function

Supports activity of the natural killer cells

Promotes differentiation of T cells, expansion, and function (cytotoxic T cells; controlling the ratio of these to T helper cells)

Necessary for antibody production

Vitamin C

Promotes production of collagen and keratinocytes; protects against the effect of oxidative damage; enhances healing of wounds; stimulates the complement cascade

Supports the function of phagocytotic cells (neutrophils, monocytes, and macrophages) as well as natural killer cell activity

Promotes differentiation of T cells, expansion, and function; regulates IFN-γ production

Enhances antibody production

Vitamin D

Stimulates the production of antimicrobial proteins; stimulates tight gut junctions; promotes homing of T cells to the skin

Promotes differentiation of monocytes to macrophages and macrophage function

Promotes antigen processing but inhibits antigen presentation; vitamin D may also compromise subsets of T cell function while enhancing others; inhibits differentiation and maturation of dendritic cells

Can compromise antibody production

Vitamin E

Protects against the effects of oxidative damage

Supports the activity of the natural killer cells

Promotes interaction between dendritic cells anti cells as well as T cell function, particularly Th1 cells; promotes il-2 production

Aids antibody production


Keeps integrity of the skin and mucosal membrane; stimulates the complement cascade

Promotes phagocytosis and natural killer cell activity

Promote Th1 cell response and proliferation of cytotoxic T cells; development of regulatory T cells;  promotes IL-2 and IFN-γ production

Aids antibody production - specifically immunoglobulin G


Promotes phagocytosis as well as natural killer cell activity

Regulates differentiation and expansion of T cells; promotes IL-2 production


Supports natural killer cell activity

Regulates differentiation and expansion of T cells; promotes IFN-γ production

Aids antibody production


Supports natural killer cell activity; regulates macrophages; supports natural killer cell activity

Regulates differentiation and expansion of T cells; promotes IFN-γ production

Adapted from Calder PC, et al.

The optimization of the immune system can be achieved through the modification of several lifestyle factors. Of these nutrition and exercise are key. Immunity is markedly compromised in elderly people, particularly those who are frail, those with obesity, those who are insufficiently nourished, and then those with an inadequate intake of micronutrients.

Nutritional inadequacy has been shown to increase susceptibility to illness and allow dysregulation of inflammation and oxidative stress, which results in a poor outcome of infection.

Can you actually boost your immune system? Here's the truth | Body Stuff with Dr. Jen Gunter


  • Childs CE, Calder PC, Miles EA. (2019) Diet, and Immune Function. Nutrients. doi:10.3390/nu11081933.
  • Calder PC. (2021) Nutrition and immunity: lessons for COVID-19. Nutr Diabetes. doi:10.1038/s41387-021-00165-0.
  • Bae YS, Shin EC, Bae YS, et al. (2019) Editorial: Stress and Immunity. Front Immunol.;10:245. doi:10.3389/fimmu.2019.00245.
  • Alagawany M, Attia YA, Farag MR, et al. (2021) The Strategy of Boosting the Immune System Under the COVID-19 Pandemic. Front Vet Sci. doi:10.3389/fvets.2020.570748.

Further Reading

Last Updated: Dec 23, 2021

Hidaya Aliouche

Written by

Hidaya Aliouche

Hidaya is a science communications enthusiast who has recently graduated and is embarking on a career in the science and medical copywriting. She has a B.Sc. in Biochemistry from The University of Manchester. She is passionate about writing and is particularly interested in microbiology, immunology, and biochemistry.


Please use one of the following formats to cite this article in your essay, paper or report:

  • APA

    Aliouche, Hidaya. (2021, December 23). How to Optimize Your Immune System. News-Medical. Retrieved on April 19, 2024 from

  • MLA

    Aliouche, Hidaya. "How to Optimize Your Immune System". News-Medical. 19 April 2024. <>.

  • Chicago

    Aliouche, Hidaya. "How to Optimize Your Immune System". News-Medical. (accessed April 19, 2024).

  • Harvard

    Aliouche, Hidaya. 2021. How to Optimize Your Immune System. News-Medical, viewed 19 April 2024,


The opinions expressed here are the views of the writer and do not necessarily reflect the views and opinions of News Medical.
Post a new comment

While we only use edited and approved content for Azthena answers, it may on occasions provide incorrect responses. Please confirm any data provided with the related suppliers or authors. We do not provide medical advice, if you search for medical information you must always consult a medical professional before acting on any information provided.

Your questions, but not your email details will be shared with OpenAI and retained for 30 days in accordance with their privacy principles.

Please do not ask questions that use sensitive or confidential information.

Read the full Terms & Conditions.

You might also like...
Females' immune system edges out males but at a cost of higher autoimmune risk