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Diet, immune system and viral infections. Italian scientific study

The correlations between diet, immune system, inflammation and viral infections are the subject of the scientific study published in the 'International Journal of Environmental Research and Public Health', thanks to the collaboration between the University of Milan Bicocca and Égalité Onlus. (1)

A wide-ranging scientific review allows us to evaluate the link between diet, immune system and intestinal microbiota. With the aim of promoting a healthy diet appropriate to the needs that Covid-19 has highlighted. And particular attention to the elderly, as the most vulnerable category.

Lifestyle, inflammation and infection risks

Overweight and obesity, unbalanced diets (particularly due to ultraprocessed foods with excessive levels of saturated fat, sugar and / or salt) and unhealthy lifestyles - physical inactivity, stress and exposure to harmful environments (e.g. pollution, cigarette smoke) - are related to chronic low-grade inflammation ( CD inflammation or LGI, Low-grade inflammation). With possible long-term onset of chronic degenerative diseases.

The rise of LGI it is in turn associated with a greater exposure to the risk of infections of various kinds, including that from Covid-19. In this case, individuals with chronic low-grade inflammation, such as the elderly and other vulnerable individuals, are more at risk of the so-called 'inflammatory storm'. A balanced immune response is vice versa a function of an optimal nutritional state, as science has amply demonstrated and the mainstream media he insists on ignoring. Prevention therefore begins at the table and in daily life.

Vitamins for the immune system

Deficiencies and low intakes of micronutrients occur in the elderly and children and can increase the risk of infectious diseases. Correcting these deficiencies can help restore the proper functioning of the immune system and increase the body's resistance to infections.

Vitamins they play a crucial role in stimulating the immune system. In particular:

- vitamin D. Its shortage is quite widespread in the Mediterranean countries. It can stimulate immune reactions and reduce the risk of infections in general. It has proved useful in mitigating the effects of Covid-19, even if the evidence gathered so far deserves further study, (2)

- C vitamin. It intervenes in the reduction and duration of upper respiratory tract infections and is a very active antioxidant to reduce ROS (reactive oxygen species) produced by immune cells to eliminate pathogenic microorganisms. Therefore, its protective function against Covid-19 is hypothesized, still awaiting clinical studies, (3)

- vitamin A. Essential to ensure the functionality and integrity of immune cells,

- Vitamin E. Protects cell membranes and promotes the activity of immune cells,

- vitamins B6, B9, B12. They regulate inflammatory states and are active in the production of antibodies and lymphocytes, as well as preserving the innate immune system.

Minerals, amino acids, Omega 3 and polyphenols

And minerals most important for antioxidant activity and modulation of immune responses are iron, zinc, selenium and copper. There are also two amino acids, glutamine and arginine, which play a fundamental role in activating immune responses.

Omega 3 fatty acids, EPA and DHA, promote the resolution of inflammation (in addition to making important health benefits). Polyphenols - which are rich in plants, fruits and derivatives (eg extra virgin olive oil) - in turn exert an effective anti-inflammatory receptor action. (4)

Prebiotics, probiotics and the immune system

The intestinal microbiota, also known as the 'second brain', can be thought of as the pivot of immune reactions. Its balance (so-called intestinal eubiosis) must in fact:

- modulation of the immune system and of the agents responsible (e.g. cytokines, lymphocytes),
- reduction of the onset of intolerances and allergies,
- maintenance of energy homeostasis, thanks to the production of short-chain fatty acids (SCFA) and modulation of body weight,
- bi-directional modulation of the brain-intestine axis (this explains the correlation between mood and digestive problems),
- functionality of organs and systems. (5)

Microbiota, health strategies

The variety and quantity of microorganisms that are allies of health in the microbiota can be favored through:

- intake in the diet of prebiotic fibers found in fruit, vegetables, legumes and whole grains (MAC, Microbiota Accessible Carbohydrates),

- contributions of polyunsaturated fatty acids and phenolic compounds, which in turn positively modulate the microbiota,

- consumption of organic food, as it can provide greater quantities and varieties of microorganisms favorable to health, (6)

- regular exercise and rest,

- dietary supplementation with probiotics. Live and vital microorganisms, in the right doses and timing, regulate the function of the organism. They are also present in some fermented products (eg yogurt, kefir). (7)

Focus on the third age

Advancing age is accompanied by the chronic condition of low intensity inflammation (inflammation, LGI) which can progressively lead to frailty in the elderly. Inadequate nutrition and a sedentary lifestyle are the first two risk factors. Immunosenescence in turn exposes the third age to a greater chance of getting sick.

It's important therefore pay attention to the quality of the diet which must include all macro- and micronutrients. (8) To generally meet these requirements, it is important to frequently vary foods in the diet to include both animal and plant-based foods. The latter are rich in phyto-compounds useful for promoting a better individual health.

Senior citizens, nutritional recommendations

The diet of the older ones must consider a greater need for proteins, to maintain the integrity and efficiency of the organs and the muscular system. And the lower absorption capacities of vitamins (K, B6, B12 and D (in primis)) and minerals, including due to taking medications. It is recommended to reduce the salt / sodium intake to mitigate the risks of arterial hypertension and cardiovascular disease. And to ensure adequate contributions, among other things, of:

- zinc. Valuable ally of the immune system and bone metabolism, it strengthens behavioral and mental functions, (9)

- iron. Its deficiency can lead to anemia. It is recommended to take it together with sources of vitamin C, to promote its absorption. Vitamins B9 and B12 are also useful in preventing anemia,

- soccer. Its need is greater, due to the demineralization of the bones. Multi-vitamin and multi-mineral supplements have proved useful in over-55, also to strengthen the immune system. (10)


To learn more the topics covered are referred to the 'Volume I - People'of our trilogy'Covid-19, the ABC'. Right in the drafting phase of the aforementioned ebook the research mentioned here began, thanks to friends Paola Palestini, Carlotta Suardi and Emanuela Cazzaniga.

Dario Dongo and Andrea Adelmo Della Penna


(1) Carlotta Suardi, Emanuela Cazzaniga, Stephanie Graci, Dario Dongo, Paola Palestini (2021). Link between viral infections, immune system, inflammation and diet. International Journal of Environmental Research and Public Health 18: 2455, https://doi.org/10.3390/ijerph18052455

(2) Dario Dongo, Andrea Adelmo Della Penna (2020) Vitamin D, immune system and Covid-19. New scientific evidence. GIFTS (Great Italian Food Trade), https://www.greatitalianfoodtrade.it/salute/vitamina-d-sistema-immunitario-e-covid-19-nuove-evidenze-scientifiche

(3) Dario Dongo, Andrea Adelmo Della Penna (2020). The potential of vitamin D in the prevention and treatment of Covid-19. GIFT (Great Italian Food Trade), https://www.greatitalianfoodtrade.it/salute/il-potenziale-della-vitamina-d-nella-prevenzione-e-trattamento-di-covid-19

(4) Dario Dongo, Salvatore Parisi (2020). Polyphenols and health. Vegetables that are friendly to the immune system. GIFTS (Great Italian Food Trade), https://www.greatitalianfoodtrade.it/salute/polifenoli-e-salute-i-vegetali-amici-del-sistema-immunitario

(5) Paola Palestini, Dario Dongo (2019). Microbiome and intestine, the second brain. GIFT (Great Italian Food Trade), https://www.greatitalianfoodtrade.it/salute/microbioma-e-intestino-il-secondo-cervello

(6) Dario Dongo, Andrea Adelmo Della Penna (2020). Organic food and the immune system, scientific evidence. GIFTS (Great Italian Food Trade), https://www.greatitalianfoodtrade.it/salute/alimenti-biologici-e-sistema-immunitario-evidenze-scientifiche

(7) Dario Dongo, Carlotta Suardi (2020). Prebiotics and probiotics, microbiome and immune system. GIFTS (Great Italian Food Trade), https://www.greatitalianfoodtrade.it/salute/prebiotici-e-probiotici-microbioma-e-sistema-immunitario

(8) Paola Palestini, Dario Dongo (2020). Coronavirus and infections, how to strengthen the defenses of the over-65s with a good diet. GIFT (Great Italian Food Trade), https://www.greatitalianfoodtrade.it/salute/coronavirus-e-infezioni-come-rafforzare-le-difese-degli-over-65-con-una-buona-dieta

(9) Meunier, N., O'Connor, J., Maiani, G. et al. (2005). Importance of zinc in the elderly: the ZENITH study. Eur J Clin Nutr 59, S1 – S4. https://doi.org/10.1038/sj.ejcn.1602286

(10) Dario Dongo, Andrea Adelmo Della Penna (2020). Over-55, strengthen the immune system with vitamin and mineral supplements. Study. GIFTS (Great Italian Food Trade), https://www.greatitalianfoodtrade.it/salute/over-55-rafforzare-il-sistema-immunitario-con-integratori-di-vitamine-e-minerali-studio

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Dario Dongo, lawyer and journalist, PhD in international food law, founder of WIISE (FARE - GIFT - Food Times) and Égalité.

Andrea Adelmo Della Penna
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Graduated in Food Technologies and Biotechnologies, qualified food technologist, he follows the research and development area. With particular regard to European research projects (in Horizon 2020, PRIMA) where the FARE division of WIISE Srl, a benefit company, participates.

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