The immune system is indispensable to our survival. Its primary function is to constantly monitor the organism to identify pathogenic agents (pathogens) and to differentiate between own (host) cells and foreign cells, and also cancer cells. Thanks to its constant activity, the organism is capable of defending itself against infections and diseases.

What we eat affects the functioning of each cell of the human body. Of course, the same applies also the cells forming part of the immune system. Diet is then one of environmental factors that can have a significant impact on our immune system.

It is worth noting that the immune system is not always a salvation to us. It can make errors, e.g. recognise own cells as foreign ones or react in an excessively sensitive way. In such a case, we are dealing with an incorrect immune response, which may manifest itself as allergic, atopic or autoimmune diseases.

Environmental factors affecting the immune system that we can control are:

  • Diet,
  • body nutritional status,
  • circadian rhythm,
  • level of physical activity,
  • stress level,
  • stimulants,
  • medicines.

Thanks to a balanced diet, optimal body weight, sufficient sleep and also its quality, regular physical activity, reducing stress (or learning how to better handle stress situations) and stimulants, we support the functioning of our immune system. At the same time, the efficiency of our own immune system drops if we disregard any of these factors.

Does an immunity-boosting diet exist?

There are many nutritional factors that affect the functioning of our immune system. If I were to respond to this question briefly, a diet with anti-inflammatory properties which boosts our immunity is a diet with an optimal protein intake, rich in vegetables and fruit, such as the Mediterranean diet, vegetarian diet or even vegan diet (with a well-balanced protein intake). We must however take a broader look at different nutritional and lifestyle factors affecting the nutritional status and the condition of the immune system.

Immunity vs. body nutritional status

Overweight and obesity inhibit the functioning of the immune system. Obesity in particular impairs immunity due to an increase in inflammatory mediators. Chronic inflammation accompanying obesity increases the risk of many diseases and infections which impair immunity.

Malnutrition caused by hunger, lack of food or diseases also negatively affects immunity-related functions. The level of immunity impairment depends in this case on the range of nutritional deficiencies and the age of the person suffering malnutrition.


Age is a factor greatly affecting our immunity. From the moment we are born, immunity is shaped by two main factors. These are exposure to external factors and our eating habits. Breastfeeding has a much more positive impact on immunity-related functions and is recommended especially in babies with a family history of immune-related conditions.

The first years of life are a very important period in terms of gaining immunity. Factors affecting the development of the immune system include the presence of pets at home, the existence of siblings, the use of antibiotics, and diet.

With time, the level of immunity in an adult may get reduced. However, in such a case, lowered immunity can be related to nutritional deficiencies. It is especially connected with protein and zinc deficiencies, which have proved to be quite common in elder people. In this situation, intervention aimed at supporting the immune system should focus on supplementing nutritional deficiencies.

Immunity vs. physical activity

Regular and moderate physical activity has great benefits for the organism, including the immune system functions. In turn, intensive physical activity causes a short-term decrease of immunity. According to literature data, such a decrease in immunity persists 3 to 72 hours after finishing intensive workout. It depends in part on carbohydrates intake. In intensive workout routine, immunity can be increased by consuming carbohydrates before and after the workout. Similarly, a low-carb diet will lower the immunity.

Immunity vs. intestines

There is a strong link between intestinal microbiota and immunity. Changes in the intestinal microflora increase the probability of many diseases, including allergy, asthma, autoimmunological diseases and many other disorders. Intestinal microbiota may change as a result of diet and environmental factors.

The factor with a very negative impact on microbiome is antibiotic therapy, thus, taking probiotics during antibiotic treatment is always recommended.

The basic nutritional intervention focussed on strengthening the intestinal microbiome is taking probiotics and prebiotics. The microbiome status is also affected by many lifestyle factors, which must be taken into account when referring to immunity. Such factors include primarily the circadian rhythm, stress level, the level of physical activity, medications taken and consumption of stimulants.

Protein vs. immunity

The deficiency of protein and other amino acids will impair the production of antibodies, and therefore immunity-related functions, in spite of the lack of vitamins and minerals deficiency. At this point, it is worth mentioning vegetarian and vegan diets, which have the greatest benefits for our immune system only on the condition that they provide us with the optimal intake of protein and necessary amino acids. Protein requirement differs depending on the physiological condition, age, health condition, body weight and the level of physical activity. Protein requirement for healthy men and women starting from the age of 19 is 0.9 g/kg of body weight.

Arginine is an exogenous amino acid that is very important for the immune system. According to studies, it has immunostimulating properties. A shorter hospitalisation time was observed in patients receiving arginine supplementation. It is justified by the beneficial effect on the process of regeneration and convalescence. Glutamine and taurine are also believed to have immunomodulating properties.

Antioxidant vitamins: C, E and beta-carotene

Vitamin C deficiency negatively affects the immune system, while no studies exist to prove immunostimulating properties of higher doses. Vitamin C improves immunity only when it is deficient. A good source of vitamin C is rosehip, peppers, blackcurrant and parsley leaves.

Vitamin E dissolves in fats. It is a strong antioxidant and shows immunostimulating properties not only during disease. Deficiencies of this vitamin are rare. They can appear for example in fat malabsorption disorders and coeliac disease. Good sources of vitamin E are vegetable oils, nuts and seeds, such as, e.g. almonds, hazelnuts or sunflower seeds.

Beta-carotene, i.e. provitamin A, is a substance used by the organism to produce vitamin A. Studies confirm the beneficial effect of carotenoids, and beta-carotene in particular, on lowering the risk of cancer and many other chronic diseases. It is, however, worth noting that high doses of vitamin A may produce an immunosuppressive effect, that is reduce the immunity. In the event of a confirmed deficiency, it is worth using supplementation, while for prevention purposes, it is better to include beta-carotene in diet. Good sources of beta-carotene are, among others, carrots, tomatoes, sweet potatoes, peppers, broccoli, spinach.

Vitamin D3

While most people have no problems with antioxidant vitamin deficiencies, the majority of the population suffers from vitamin D deficiency. Vitamin D3 level can be checked by the 25-OH vitamin D test. Exposure to a deficiency of this vitamin, which is of key importance to immunity, increases in the autumn and winter period due to less sunlight. Vitamin D3 deficiency is related to a higher risk of infections and autoimmune diseases. Supplementation of this vitamin is recommended and is safe. Exact recommendations on supplementation can be found in a separate article under this link.


Our diet greatly affects the functioning of the immune system. A well-balanced Mediterranean diet will be very beneficial, as abounds in vegetable and fruit, which are a good source of fibre, vitamins and minerals. It is also important to consume sufficient quantities of protein – standard demand is 0.9-1.5 g/kg of body weight and depends on several factors, such as the physiological condition, age or health condition. With increased activity, the protein requirement can be higher, and it should be individually determined. It is important to maintain the right body weight, because either underweight or overweight and obesity will negatively affect the immune system. Nutritional deficiencies are a special threat. An important vitamin of key importance for immunity and which is deficient in a significant part of the population is vitamin D3. Apart from strictly diet-related factors, the following are key to appropriate immunity: regular circadian rhythm, learning ways to deal with stress, moderate and regular physical activity, elimination of stimulants (smoking tobacco, abuse of alcohol).
When taking medication, especially antibiotics, is necessary, they should be taken strictly in accordance with doctor’s recommendations (duration of therapy, dose), without forgetting about the need to use gastroprotective probiotics.