Foods That Help Our Immune System

About the immune system

With the flu season in full force, it is now more important than ever to focus on your health and boosting your immune system. 

The immune system consists of different organs, tissues, cells, and proteins that work together through bodily processes to protect the body against bacteria, viruses and pathogens. This system is able to distinguish healthy cells from unhealthy cells through the release of white blood cells in the bloodstream. There are two types of white blood cells – phagocytes and lymphocytes. Phagocytes include neutrophils, macrophages, dendritic cells, monocytes and mast cells which surround and absorb pathogens, causing their destruction. Lymphocytes including B lymphocytes, T lymphocytes, and natural killer cells that  help the body to recognise and remember previous invaders if they return to the body again.1

A good way to keep your immune system strong is through your diet. There are many different types of foods that can boost your immunity which range from fruit and vegetables to nuts, yogurt and meat. This article will explore these options and tell you just how they work to boost our immune system. 

Foods that boost our immune system

Citrus fruits

Vitamins are essential for the body and normal health, but the body cannot produce vitamins itself so they must be received through food. The key vitamins involved in the immune system are vitamin B6, A, C, D and E which aid in body development and repair processes that ultimately increases immunity. 

Vitamin C is a water-soluble vitamin and citrus fruits such as lemons, limes, oranges and grapefruits are a high source of vitamin C. Studies show that a high dose of vitamin C of about 12g per day was enough to significantly improve the condition of patients with severe acute respiratory tract infections.2 Research also shows that vitamin C works by increasing the response of cells in the immune system which decreases the severity of respiratory infections and colds.2

For continued health, the recommended daily amount of vitamin C for adults is 75mg for women and 90mg for men. 


Spinach is a vegetable rich in vitamin C and A. Vitamin A is a fat-soluble vitamin that is essential for growth, development, immunity and eye vision. Vitamin A has different active forms including retinol, retinal and retinoic acid. Retinoic acid works by increasing the production of anti-inflammatory cytokines and antibodies which work to protect the body against viral infections such as measles. A recent study showed that a deficiency in vitamin A caused excessive inflammation and increased the risk of viral infection.2


Yoghurt is a great source of vitamin D. Studies show that vitamin D increases immunity by increasing the natural killer cells called cytotoxic T cells and macrophages, which are the cells involved in fighting diseases in your body.2

Yoghurt is also a good source of probiotics which are living microorganisms that aid in general health and immunity. Probiotics work through different mechanisms to boost the immune system and ultimately protect the body against gastrointestinal pathogens.3

For a healthier option, opt for plain yoghurts instead of flavoured yoghurts with added sugar. You can sweeten plain yoghurt by adding a drizzle of honey or by adding fruit.

Green tea

Green tea is packed with both flavonoids and EGCG which are a type of antioxidant. Green tea boosts the immune system by protecting the body against oxidants and free radicals. When the body is unable to deal with free radicals and oxidative stress, it is more vulnerable to diseases and the risk of infection increases. Oxidative stress is often linked with stroke, cancer, heart disease, respiratory diseases and Parkinson’s disease. 

Therefore green tea is a great way to provide the body with enhanced immunity and protection against various diseases.4 Green tea can be a healthier alternative to coffee or black tea, although all three have their benefits.

Red meat

Red meat is packed with iron which is essential for the healthy development of the immune system. Iron plays an important role as it is needed for protein synthesis, DNA synthesis and repair, cellular respiration, maturation of lymphocytes and regulation of gene expression. Iron-deficiency results in reduced innate immunity or non-specific immunity which is the defence system that you were born with. This is the body’s first line of defence against pathogens and it prevents harmful materials from entering your body.2


Certain types of shellfish such as oysters, mussels, crab and lobster are packed with zinc. Zinc plays an important role in immunity and antibody production by regulating the function of immune cells such as macrophages, neutrophils, T cells and B cells. Animal studies have shown that a zinc deficiency leads to a loss of immunity.2 Another recent study showed that zinc had the ability to reduce respiratory tract infections such as pneumonia, rhinovirus infection or the common cold.2 

Red peppers

Red peppers are another good source of vitamin C. In fact, they contain three times more vitamin C than an orange and so they are a great addition to your diet.2 They are also a rich source of beta-carotene which is converted into vitamin A, and helps keep your eyes and skin healthy along with its great immunity benefits.2


Dates are rich in phytochemicals and are therefore a good source of antioxidants. Antioxidants are known to increase immunity and are effective against chronic diseases such as cardiovascular disease and cancer. The three antioxidants that contribute to these amazing effects are flavonoids, carotenoids and phenolic acid. Flavonoids work by reducing inflammation which lowers your risk of chronic diseases such as Alzheimer’s disease, diabetes and cancer. Carotenoids are turned into vitamin A by your body which helps boost immunity and protect eye health. Lastly, phenolic acid boosts immunity by reducing free radicals to prevent cancer and other diseases.1


Almonds are a good source of vitamin E as well as manganese, magnesium and fiber. Vitamin E is a powerful antioxidant similar to vitamin C and has the benefit of increasing immunity. This vitamin works by regulating the function of T cells as well as increasing antioxidant activity through the regulation of the expression of antioxidant enzymes. A study revealed that vitamin E could be useful in the treatment of the hepatitis B virus in children. Vitamin E is an antiviral agent as it plays a role in decreasing the replication of the virus which therefore boosts immunity.2

Sunflower seeds

Similar to almonds, sunflower seeds are a good source of vitamin E, which enhances immune function by fighting off free radicals which can damage cells. In addition to being a good source of vitamin E, sunflower seeds are also packed with copper. Copper improves natural killer cell activity through its role in macrophages, neutrophils and monocytes, which are the cells involved in the immune system. It is known to be effective against many viruses including influenza viruses and noroviruses.2

Oily fish

Oily fish such as salmon, tuna and pilchard are a rich source of omega-3 fatty acids. Findings show that these fish can enhance the function of the immune system by reducing inflammation and increasing the body’s ability to fight off illnesses.2

Brazil nuts

Brazil nuts are a great source of selenium which play a key role in increasing immunity, protecting against oxidative stress and maintaining antibody levels. Selenium protects against oxidative stress by removing potentially damaging free radicals. Research shows that selenium is effective against HIV, hepatitis and influenza A viruses.2


Turmeric is known for its anti-inflammatory and antioxidant properties. The yellow component of turmeric called curcumin is responsible for these beneficial effects. Curcumin works with several cells involved in the immune response such as macrophages, B cells, T cells and dendritic cells. A recent study showed that when given to patients, curcumin led to a decrease in inflammation and allergies, and an increase in immunity against pathogens, cardiovascular diseases and tumour cells. In addition, curcumin can boost the immunity of elderly patients and reduce their risk of infectious diseases.5 


When you’re sick, you often opt for a nice warm bowl of chicken soup which actually has tremendous benefits. Poultry such as chicken and turkey are a rich source of vitamin B6. Vitamin B6 aids in the chemical reactions in the immune system and also helps the body create new red and white blood cells. A deficiency in vitamin B6 could negatively affect the body’s immune response.6


Garlic is a common household ingredient used in many dishes all over the world and it is known to be effective at fighting infections. Adding garlic to your food can increase the number of T-cells in your blood which increases your body’s ability to fight viruses. In addition, studies show that eating garlic extract can reduce the severity of common colds and flu.7

Other ways to boost our immune system

Keeping healthy and maintaining a healthy diet is a great way to boost your immunity. Another important way of boosting immunity is through immunisation such as the annual flu vaccine, which can help protect you and others. As well as this, exercising regularly, avoiding smoking, staying hydrated, and sleeping well are general tips to enhance your immunity and help you to stay healthy during flu season. 


Overall, keeping your body healthy is an effective way of boosting the immune system and reducing the risk of infections. A combination of healthy food in your diet including vitamins C, D, E, B6, and A as well as zinc, copper, selenium, and iron is a great way to ensure your body has an increased ability to protect itself against bacteria and viruses. 


  1. Bi̇çer A. A study on foods that boost the immune system during the covid-19 pandemic. NATURENGS [Internet]. 2020 Nov 11 [cited 2022 Nov 25];28–37.
  2. Thirumdas R, Kothakota A, Pandiselvam R, Bahrami A, Barba FJ. Role of food nutrients and supplementation in fighting against viral infections and boosting immunity: A review. Trends in Food Science & Technology [Internet]. 2021 Apr 1 [cited 2022 Nov 25];110:66–77.
  3. Ashaolu TJ. Immune boosting functional foods and their mechanisms: A critical evaluation of probiotics and prebiotics. Biomedicine & Pharmacotherapy [Internet]. 2020 Oct 1 [cited 2022 Nov 25];130:110625.
  4. Chacko SM, Thambi PT, Kuttan R, Nishigaki I. Beneficial effects of green tea: A literature review. Chin Med [Internet]. 2010 Apr 6 [cited 2022 Nov 25];5:13.
  5. Allegra A, Mirabile G, Ettari R, Pioggia G, Gangemi S. The impact of curcumin on immune response: an immunomodulatory strategy to treat sepsis. International Journal of Molecular Sciences [Internet]. 2022 Jan [cited 2022 Nov 25];23(23):14710.
  6. Qian B, Shen S, Zhang J, Jing P. Effects of vitamin b6 deficiency on the composition and functional potential of t cell populations. J Immunol Res [Internet]. 2017 [cited 2022 Nov 25];2017:2197975. 
  7. Arreola R, Quintero-Fabián S, López-Roa RI, Flores-Gutiérrez EO, Reyes-Grajeda JP, Carrera-Quintanar L, et al. Immunomodulation and anti-inflammatory effects of garlic compounds. J Immunol Res [Internet]. 2015 [cited 2022 Nov 25];2015:401630.
This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Suad Mussa

Bachelor of Science – BSc, Biology. Queen Mary University of London

Suad Mussa is a biology graduate with a strong passion for medical writing and educating the public about health and wellbeing.

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