Immune system health is never taken for granted – in fact, in the current climate, immunity, and health are arguably more crucial than before. Our immune systems protect us from foreign bodies and harmful environmental factors. In order for them to perform at their best without problems, our immune systems need our support: with the right diet, sleep quality, little stress, and proper hygiene.
Our immune system works like a machine: It needs the right fuel and enough of it. It gets bogged down if it has to run at full speed all the time. Like a machine, you yourself can maintain your body’s immunity regularly and contribute to an optimal and well-oiled immune system. By following a healthy diet, organizing your daily routine in a way that eliminates stress and gives you enough time to sleep, you create the necessary conditions to boost your immune system.
Read on for important insights into immune system boosters – that is, foods, nutrients, and vitamins for immune system health, as well as how you can optimize your health with the right nutrients and lifestyle changes.
What Is the Immune System?
Your immune system works with a range of different cells and chemical processes to protect you from pathogens. Your immune system needs strength, so that it can fight pathogens properly. It gets this from a healthy diet, sufficient exercise, and rest.
If you lack important nutrients or are plagued by stress in everyday life, the function of your immune system decreases. Especially in children and the elderly, care must be taken to maintain a strong immune system. In childhood, the immune system is not yet mature; in old age, immune function is lower.[1, 2]
Did you know that the production of T cells decreases with age? Therefore, the number of infections may increase in elderly people, especially in their respiratory tract.[1, 2]
The following table gives you a brief overview of the most important terms related to the immune system.
Table: Your immune system at a glance
These are proteins on the surface used by immune cells to recognize foreign bodies
They control foreign bodies
They produce antibodies and memory cells
B memory cells
They produce antibodies
These are aggressive oxygen molecules that promote inflammation
These combat bacteria and allergies
These include B cells, T cells, natural killer cells, natural killer T cells
These are white blood cells – granulocytes, lymphocytes, monocytes
These are monocytes, which are found in tissue
These are scavenger cells that digest pathogens
Natural killer cells
These detect cancerous or virus-infected cells and initiate cell death
Natural killer T cells
These are a combination of T cells and natural killer cells
This is when pathogens are digested by monocytes
These recognize antigens
This is the organ behind the breastbone, responsible for producing immune cells
What Are 5 Ways to Boost Your Immune System?
In order for your immune system to perform its defensive function optimally, you should ensure you optimize the following in your everyday life:[3, 4]
- Maintain a balanced diet and body weight, avoid nutrient deficiencies
- Exercise regularly
- Avoid smoking and limit or avoid alcohol consumption
- Reduce stress and promote a healthy sleeping pattern
- Take preventive health and hygiene measures – through disinfection, vaccination, etc.
Immune System Boosters: Which Nutrients Do I Need?
Without nutrients, nothing works in the body – and, of course, this also applies to the immune system. Carbohydrates, fats, and proteins provide the body with an energy source. Vitamins serve as catalysts and boost your immune system.
In addition, vitamins, minerals, and secondary plant compounds have an antioxidant effect. Together, they prevent free radicals from causing cellular damage.
Your body can also form antioxidants on its own. However, in order for them to protect cells, they require minerals such as zinc, manganese, iron, selenium, and copper.
Are There Nutrients That Boost Your Immune System?
To boost your immune system, you should always ensure that your diet meets your needs. As soon as the body’s defense weakens and becomes vulnerable to infections, this can lead to a vicious circle. For example, a nutrient deficiency might lead to an infection. This, in turn, can lead to a further loss of nutrients through deficiency symptoms such as fever, loss of appetite, or diarrhea.
You should regularly check your vitamin or mineral levels with nutrient deficiency tests – for peace of mind. According to studies, the following nutrients have the greatest influence on the immune system:
- Vitamins A, C, D and E
- Zinc and selenium
- Omega-3 and omega-6 fatty acids
- Prebiotics and probiotics
Particularly in old age, it is absolutely crucial to maintain a diet that meets individual needs. With increasing age, the feeling of lack of appetite can increase, which can lead to malnutrition. Subsequently, a protein deficiency leads, for example, to a decrease in T cells.
Vitamins for Immune System Health: How Does Vitamin D Help?
For a long time, it was assumed that vitamin D only regulates bone strength and stability. However, researchers have been able to show that vitamin D strengthens our immune cell activity, especially macrophages. Current research results indicate that an adequate vitamin D intake reduces the risk of autoimmune diseases, such as type 1 diabetes.
It is thus no surprise that vitamin D is considered one of the most important vitamins to boost immune system health. To prevent vitamin D deficiency, you can check your vitamin D levels regularly to make sure that they are not low. Spend at least 30 minutes outside on sunny days and take vitamin D supplements if your levels are too low.[1, 5, 6]
How Does Vitamin A Affect the Immune System?
Did you know that our gut mucosa functions as a barrier for our immune system; it prevents harmful bacteria and viruses from entering the bloodstream. This is why gut health is currently such a promoted and insightful health topic.
Vitamin A, or its precursor beta-carotene, is found in offal as well as in orange, yellow, and green fruits, and vegetables.
Vitamins to Boost Immune System Health: What Should I Take?
When it comes to immune system function, vitamin C and vitamin E are a great team. Vitamin E protects cell membranes from free radicals, meaning cells remain stable and can perform their functions. After carrying out its tasks in our bodies, vitamin E itself becomes a free radical and vitamin C converts the vitamin E radical back into an ordinary vitamin E molecule.
Our body also needs vitamin C to make B and T cells – and vitamin C additionally helps immune cells find pathogens more quickly. Vitamin E is found mainly in vegetable oils and nuts, while vitamin C is abundant in peppers, kiwi, berries, and citrus fruits.[1, 7]
Do Minerals Keep Your Immune System Strong?
Zinc and selenium are found in high amounts in whole grains and nuts. Iron is found in meat, nuts, whole grains, broccoli, and kale.
Gut Health: Do Probiotics Improve Immune System Health?
Did you know that a total of 70 percent of our immune system is located in our intestine? Gut flora located there fight pathogens and prevent them from spreading around the body. Infections, antibiotics, an unhealthy diet, and chronic stress promote imbalanced gut flora. Harmful bacteria can thus gather in your intestine, pass through your gut mucosa more easily, and enter your bloodstream.
To curb the effects of antibiotics, it is recommended that you take probiotics – dietary supplements containing intestinal bacteria to strengthen your gut microbiome. Fermented foods such as sauerkraut, kefir and kimchi, and cheeses such as mozzarella and cheddar contain probiotic bacteria.
Prebiotics support the growth of intestinal bacteria that fight pathogens and strengthen our intestinal lining. Prebiotics are found in whole grains, fruits, and vegetables.
To find out whether your gut is healthy, you can take a gut flora test, which screens your sample for the composition of various bacteria – both good and bad – in your stool. You can either organize to take this test with your doctor, a registered homeopath, or by purchasing a test online from a reputable retailer specializing in health diagnostics.
Does Omega-3 Improve Immune System Health?
To optimize your omega-3 levels, you can consume a tablespoon of cold-pressed virgin flax oil daily, a handful of nuts, and eat coldwater fish, such as mackerel or herring once a week. Omega supplements based on fish oil or, as a vegan option, algae oil are also an option.
Please note: Only take supplements if you have a confirmed deficiency. Make sure you eat a balanced and varied diet to absorb all the important nutrients.
How Does Obesity Affect Immunity?
Obesity is accompanied by a number of inflammatory processes: fat cells secrete adipokines, proteins that promote inflammation. They interfere with immune system function and our white blood cells’ ability to transmit signals – inflammation within the body is therefore not detected in time. In addition to excess weight, large amounts of food that exceed actual requirements can also promote inflammation.[11,12]
Alcohol & Smoking: Does Smoking Weaken Your Immune System?
Sometimes it is said, albeit jokingly, that alcohol and cigarettes could perhaps also kill viruses and bacteria with their toxins. Unfortunately, this is not true. Studies suggest that alcohol abuse even inhibits certain immune cells, weakening the immune system and increasing the risk of infection.. If you spend the evening heavily intoxicated in a busy bar or club, your body is less able to fight off the pathogens that are spread around.
In one study, it was proven that 20 minutes after test participants drank a large amount of vodka, inflammation levels and defense processes in the body briefly increased. After two hours, however, the immune system was depleted, and the number of defence cells such as monocytes (phagocytes) and natural killer cells decreased. According to the researchers, therefore, even a single drink increases the risk of becoming ill.
However, individual studies suggest that limited alcohol consumption may actually boost your immune system in the long run. However, these results are controversial among researchers – and other recent studies suggest that even smaller amounts of alcohol are generally unhealthy and could increase the risk of cancer and other illnesses.
Smoking has an effect on the outermost protective walls of our immune system: The mucous membranes of our respiratory tract and the cilia of our lungs. This makes it easier for pathogens to penetrate our airways and can thus increase the risk of pneumonia, among other things.
Defense cells also appear to suffer from nicotine intake. It has been shown that smokers, on average, suffer more frequently from infections such as colds.
Does Stress Weaken an Immune System?
Chronic stress and thus elevated cortisol levels prevent immune cells from fighting pathogens in a timely and effective manner. Furthermore, chronic stress impairs the formation of lymphocytes and humoral immune response – the body produces fewer antibodies to fight pathogens.[10,13]
Making your everyday life less stressful not only brightens your mood, but it also strengthens your immune response. Your body can produce more and more active T cells. Natural killer cells also work more effectively. Well-being is furthermore thought to lower the risk of autoimmune diseases and the incidence of free radicals.
To make everyday life less stressful, implement these changes in your life:
- Get sufficient and restful sleep to reduce your stress levels
- Do exercise to counteract stress – especially if it’s a sport you love
- Drink black tea; this is said to counteract the release of stress hormones
- Consume enough omega-3 fatty acids, B vitamins, and antioxidants via your diet
- Enjoy daily relaxation techniques such as meditation, yoga, or qigong
Being with your loved ones stimulates the production of the love hormone oxytocin. This hormone reduces stress levels and even strengthens the immune system.
How Does Sleep Impact Your Immune System?
During sleep, our bodies produce defence cells, such as T cells and natural killer cells. In this time, lymphocytes are particularly active. Their task is to recognize potential threats in good time, while recovery and repair processes take place.
If you don’t receive sufficient sleep, fewer immune cells are also produced. The body then releases more inflammatory substances and stress hormones, which reduce immune activity.[17, 18]
With the right sleeping routine, you can drastically boost your immune system:
- Always try to go to bed and get up at the same time.
- Your bedroom should have a temperature of around 64 degrees Fahrenheit.
- Don’t watch TV or look at your smartphone two hours before bedtime.
- Have your last meal of the day four hours and your last coffee six hours before bedtime.
- The sleep hormone melatonin plays an essential role in you falling asleep and staying asleep. If there are disturbances in your melatonin balance, sleep supplements can help.
How Can Sport Affect Your Immune System?
Researchers observed that physical activity can increase the activity of natural killer cells and granulocytes. In addition, exercise is thought to curb the weakening of the immune system, which happens when you get older. Try to schedule five 30-minute exercise sessions a week. But don’t overdo it – overly intense workouts may weaken your immune system and lead to muscle fatigue.
If you consume carbohydrates after your exercise session, the risk of inflammation may be reduced.[20, 21]
While free radicals are formed after exercise, they are not formed to a degree that harms the immune system. 
Is There a Test to Check Your Immune System?
With an immune system test or an immunodeficiency test, you can take a blood sample within the comfort of your own home for doctors to analyze in a specialized laboratory. Doctors commonly check the presence of lymphocytes in your blood – an indication of how strong or weak your immune system is at the time the test was taken.
Following the laboratory analysis, you usually receive a report telling you about the lymphocyte count in your blood and how you will be able to boost your immune system to an optimal level to fight off future infections.
Vitamins for Immune System Health: Which Should I Take?
Immune system boosters are foods or dietary supplements that are designed to act as immune system boosters. Often, such supplements to boost immune system health are marketed as miracles in fighting against infections. However, studies show that most of them do not prevent infections completely: Taking either zinc or vitamin C supplements, for example, does not prevent a cold – they may only shorten the duration of the illness.
Studies have been conducted on foods and supplements to increase natural killer cells in the body, such as vitamin A, vitamin E, garlic, ashwaganda, and curcumin. One particular study showed that there was an increase in NK activity after rats were given ashwagandha extract. These studies are only preliminary, and more studies need to be carried out in order to investigate this topic further.
Dietary supplements should mainly be taken when there is a confirmed deficiency or when certain nutrients cannot be absorbed from your diet due to illness, allergies, or intolerances.[23, 24] There are also home remedies or foods that, according to studies, can function as immune system boosters. So far, proven benefits have mainly been observed in studies conducted on animals.
Immune System Boosters: Which Foods Should I Eat?
Ginseng, ginger, and garlic promote a healthy immune system. They strengthen the activity of immune cells such as natural killer cells, macrophages, and granulocytes.[25, 26]
Spicy foods such as chili or peppers contain the secondary plant compound capsaicin – this supports the elimination of defective or harmful cells and pathogens.
Curcumin from turmeric can increase the production of B cells, T cells, and natural killer cells. The phytochemical may also increase the response rate of the immune system.
The amino acid theanine from green or black tea and the medicinal plant echinacea was found to improve immune function in rats.[29, 30]
How Can I Help My Body Fight Off Infections?
You can not only boost your immune system in the long term, but also ensure that you come into contact with fewer pathogens in everyday life. Hygiene measures to do this may seem small and insignificant, yet these will greatly help support your body’s defense.
- Good hand hygiene is a must. Wash your hands regularly if you have come into contact with possible sources of pathogens – whether in the bathroom, kitchen, or public bathrooms.
- When you sneeze or cough, cover your mouth with your elbow to avoid infecting others.
- Open sores should be washed out immediately with lukewarm water and covered with a bandage or plaster.
- Condoms can protect against sexually transmitted infections, such as HIV, syphilis, and gonorrhea.
- To remove as many pathogens as possible from food, wash food thoroughly first. Raw animal products must be well heated and cut on a separate cutting board. If you are going abroad, it is advisable to find out in advance whether the drinking water is contaminated with bacteria.
Tip: Before traveling, always find out how high the risk of infectious diseases is in the respective country, so that you can take appropriate precautions.
How Do Vaccinations Affect the Immune System?
Vaccinations are used to protect you against certain diseases. Small amounts of a certain pathogen are injected into your body, after which your body can produce antibodies in advance. If an infection with this pathogen should occur, your body can counter the infection with the appropriate antibodies. You can get vaccinated against the following diseases and pathogens:
- Tetanus, diphtheria
- Whooping cough, influenza (flu)
- Hepatitis B
- Shingles, pneumococcus, rotavirus, meningococcus, HPV
- Measles, mumps, rubella, chickenpox, polio
How Can You boost Your Immune System – at a Glance
How Can I Strengthen My Immune System?
To ensure that your immune system protects you from infections in the long term, you should make sure you eat a balanced diet that meets your needs, so that you take in enough nutrients to boost your immune system. These include vitamins A, C, D and E, zinc, selenium, and iron. Furthermore, you should make sure you regularly get a restful sleep, sufficient exercise, and maintain low stress levels in everyday life. Vaccinations, vitamins for immune system health, and optimal personal hygiene also prevent the risk of infections.
Which Are the Best Foods for Immune System Health?
Foods that are said to strengthen the immune system include ginger, garlic, and medicinal plants such as ginseng or echinacea. Spicy foods containing the active ingredient capsaicin are also said to be immune system boosters. Theanine from green and black tea and curcumin from turmeric are said to have similar positive effects on your immune system.
How Do I Protect Myself from Pathogens?
When viruses or other pathogens are going around, you can take small steps to help prevent you and others from catching them. Wash your hands thoroughly, sneeze into your elbow and not your hand, and always wash fresh food. During flu season, the flu vaccination can also be beneficial.
 Calder, P. C. ‘Feeding the immune system’, Proc Nutr Soc, vol. 72(3), pp. 299–309, August 2013, doi: 10.1017/S0029665113001286.
 Brodin, P., Davis, M. M., ‘Human immune system variation’, Nat Rev Immunol, vol. 17(1), pp. 21–29, January 2017, doi: 10.1038/nri.2016.125.
 Sarkar, D., Jung, M. K., Wang, H. J. ‘Alcohol and the Immune System’, Alcohol Res, vol. 37(2), pp. 153–155, 2015.
 Qiu, F. et al. ‘Impacts of cigarette smoking on immune responsiveness: Up and down or upside down?’, Oncotarget, vol. 8(1), pp. 268–284, November 2016, doi: 10.18632/oncotarget.13613.
 Prietl, B., Treiber, G., Pieber, T. R., Amrein K.‘Vitamin D and Immune Function‘, Nutrients, vol. 5(7), pp. 2502–2521, July 2013, doi: 10.3390/nu5072502.
 Wu, D., Lewis, E. D., Pae, M., Meydani, S. N. ‘Nutritional Modulation of Immune Function: Analysis of Evidence, Mechanisms, and Clinical Relevance’, Front. Immunol., vol. 9, 2019, doi: 10.3389/fimmu.2018.03160.
 Carr, A. C., Maggini, S. ‘Vitamin C and Immune Function’, Nutrients, vol. 9(11), November 2017, doi: 10.3390/nu9111211.
 Kiecolt-Glaser, J. K., Glaser, R., Christian, L. M. ‘Omega-3 Fatty Acids and Stress-Induced Immune Dysregulation: Implications for Wound Healing’, Mil Med, vol. 179(110), pp. 129–133, November 2014, doi: 10.7205/MILMED-D-14-00167.
 Patterson, E., Wall, R., Fitzgerald, G. F., Ross, R. P., Stanton, C. ‘Health Implications of High Dietary Omega-6 Polyunsaturated Fatty Acids’, J Nutr Metab, vol. 2012, 2012, doi: 10.1155/2012/539426.
 Bae, Y.-S., Shin, E.-C., Bae, Y.-S., Van Eden, W. ‘Editorial: Stress and Immunity’, Front. Immunol., vol. 10, 2019, doi: 10.3389/fimmu.2019.00245.
 de Heredia, F. P., Gómez-Martínez, S., Marcos, A. ‘Obesity, inflammation and the immune system’, Proc Nutr Soc, vol. 71(2), pp. 332–338, May 2012, doi: 10.1017/S0029665112000092.
 Andersen, C. J., Murphy, K. E., Fernandez, M. L. ‘Impact of Obesity and Metabolic Syndrome on Immunity12’, Adv Nutr, vol. 7(1), pp. 66–75, January 2016, doi: 10.3945/an.115.010207.
 Segerstrom, S. C., Miller, G. E. ‘Psychological Stress and the Human Immune System: A Meta-Analytic Study of 30 Years of Inquiry’, Psychol Bull, vol. 130(4), pp. 601–630, July 2004, doi: 10.1037/0033-2909.130.4.601.
 Abdurachman und Herawati, N., ‘THE ROLE OF PSYCHOLOGICAL WELL-BEING IN BOOSTING IMMUNE RESPONSE: AN OPTIMAL EFFORT FOR TACKLING INFECTION’, Afr J Infect Dis, vol. 12(1) Suppl, pp. 54–61, March 2018, doi: 10.2101/Ajid.12v1S.7.
 Steptoe. A. et al. ‘The effects of tea on psychophysiological stress responsivity and post-stress recovery: a randomised double-blind trial’, Psychopharmacology (Berl.), vol. 190(1), pp. 81–89, January 2007, doi: 10.1007/s00213-006-0573-2.
 Schlack, R., Hapke, U., Maske, U., Busch, M. Cohrs, S ‘Häufigkeit und Verteilung von Schlafproblemen und Insomnie in der deutschen Erwachsenenbevölkerung’, Bundesgesundheitsbl., vol. 56(5), pp. 740–748, May 2013, doi: 10.1007/s00103-013-1689-2.
 Besedovsky, L., Lange, T. Born, J. ‘Sleep and immune function’, Pflugers Arch, vol. 463(1), pp. 121–137, January 2012, doi: 10.1007/s00424-011-1044-0.
 Asif, N., Iqbal, N. R., Nazir, C. F. ‘Human immune system during sleep’, Am J Clin Exp Immunol, vol. 6(6), pp. 92–96, December 2017.
 Dimitrov, S. et al. ‘Gαs-coupled receptor signaling and sleep regulate integrin activation of human antigen-specific T cells’, Journal of Experimental Medicine, jem.20181169, February 2019, doi: 10.1084/jem.20181169.
 Nieman, D. C., Wentz, L. M. ‘The compelling link between physical activity and the body’s defence system’, Journal of Sport and Health Science, vol. 8(3), pp. 201–217, May 2019, doi: 10.1016/j.jshs.2018.09.009.
 Fernandez, D. M., Clemente, J. C., Giannarelli, C. ‘Physical Activity, Immune System, and the Microbiome in Cardiovascular Disease’, Front. Physiol., vol. 9, 2018, doi: 10.3389/fphys.2018.00763.
 Campbell, J. P., Turner, J. E. ‘Debunking the Myth of Exercise-Induced Immune Suppression: Redefining the Impact of Exercise on Immunological Health Across the Lifespan’, Front Immunol, vol. 9, April 2018, doi: 10.3389/fimmu.2018.00648.
 ‘Markt für Nahrungsergänzungsmittel in Deutschland 2018 - Lebensmittelverband Deutschland’, available at https://www.lebensmittelverband.de/de/verband/organisation/arbeitskreise/arbeitskreis-nahrungsergaenzungsmittel-ak-nem/20181029-zahlen-nahrungsergaenzungsmittel-markt-2018, accessed on December 18, 2019.
 Cassa Macedo, A., Oliveira Vilela de Faria, A., Ghezzi, P.‘Boosting the Immune System, From Science to Myth: Analysis the Infosphere With Google’, Front Med (Lausanne), vol. 6, July 2019, doi: 10.3389/fmed.2019.00165.
 Arreola, R., et al. ‘Immunomodulation and Anti-Inflammatory Effects of Garlic Compounds’, J Immunol Res, vol. 2015, 2015, doi: 10.1155/2015/401630.
 Kang, S., Min, H. ‘Ginseng, the “Immunity Boost”: The Effects of Panax ginseng on Immune System’, J Ginseng Res, vol. 36(4), pp. 354–368, October 2012, doi: 10.5142/jgr.2012.36.4.354.
 Granato, M., Gilardini Montani, M. S., Filardi, M., Faggioni, A. Cirone, M. ‘Capsaicin triggers immunogenic PEL cell death, stimulates DCs and reverts PEL-induced immune suppression’, Oncotarget, vol. 6(30), pp. 29543–29554, August 2015.
 Jagetia, G. C., Aggarwal, B. B. ‘“Spicing up” of the immune system by curcumin’, J. Clin. Immunol., vol. 27(1), pp. 19–35, January 2007, doi: 10.1007/s10875-006-9066-7.
 Li, C. et al. ‘L-Theanine Improves Immunity by Altering TH2/TH1 Cytokine Balance, Brain Neurotransmitters, and Expression of Phospholipase C in Rat Hearts’, Med Sci Monit, vol. 22, pp. 662–669, February 2016, doi: 10.12659/MSM.897077.
 Zhai, Z. et al. ‘Enhancement of Innate and Adaptive Immune Functions by Multiple Echinacea Species’, J Med Food, vol. 10(3), pp. 423–434, September 2007, doi: 10.1089/jmf.2006.257.
 Molina, P. E., Happel, K. I., Zhang, P., Kolls, J. K., Nelson, S. ‘Focus On: Alcohol and the Immune System’, Alcohol Res Health, vol. 33(1–2), pp. 97–108, 2010.
 Afshar, M. et al. ‘Acute Immunomodulatory Effects of Binge Alcohol Ingestion’, Alcohol, vol. 49(1), pp. 57–64, February 2015, doi: 10.1016/j.alcohol.2014.10.002.
 Hartz, S. M. et al. ‘Daily Drinking Is Associated with Increased Mortality’, Alcoholism: Clinical and Experimental Research, vol. 42(11), pp. 2246–2255, 2018, doi: 10.1111/acer.13886.
 Deutsches Krebsforschungszentrum, ‘Fakten zum Rauchen“, available at: https://www.dkfz.de/de/tabakkontrolle/Fakten_zum_Rauchen.html, accessed on March 18, 2020.
 Robert Koch Institut ‘Empfehlungen der Ständigen Impfkommission beim Robert Koch-Institut – 2019/2020’, Epidemiologisches Bulletin, no. 34, 2019.
 Public Health England ‘Research and analysis 2. Important finding’ Available at https://www.gov.uk/government/publications/covid-19-mental-health-and-wellbeing-surveillance-report/2-important-findings-so-far, December 17, 2020, accessed February 19, 2021.
 Grudzien M., Rapak A. ‘Effect of Natural Compounds on NK Cell Activation,’ J Immunol Res., 2018, vol. 2018:4868417, December 25, 2018, doi:10.1155/2018/4868417