Diet can reduce risk of COVID-19, Polish scientists show

The effectiveness of a diet rich in vegetables and fruits, with a suitable amount of garlic, nuts, whole grain products and legumes, in protecting against the coronavirus disease can reach 80 percent.

'The results and conclusions of our research apply to young, physically moderately active, healthy, non-obese, non-smoking adults. In this group, a well-balanced diet, rich in vegetables, fruits and nuts, as well as groats and legumes, suitable amount of onion and garlic, could reduce the risk of COVID-19 by more than 80 percent. It did not guarantee that a person would not get sick, because this is impossible, but it significantly reduced that risk', emphasizes Dr. Paweł Jagielski, the first author of the study from the Department of Nutrition and Drug Research, Institute of Public Health, Faculty of Health Sciences, Jagiellonian University Medical College.

In a paper published in Nutrients, Dr. Jagielski and colleagues described the 2020/2021 research project aimed at assessing the impact of physical activity, nutritional behaviours and gut microbiomes of people on a vegetarian and non-vegetarian diets on the risk of SARS-COV-2 infection.

'The numerous consequences of the coronavirus disease 2019 (COVID-19) pandemic in healthy young people and the lack of clarity as to the long-term disease outcomes have spurred the search for risk factors for SARS-CoV-2 infection', explain researchers from Kraków.

95 people were recruited for the experiment: 54 on a traditional diet and 41 vegetarians. All subjects were in the 25-45 age group, they had no chronic diseases and their BMI was in the range of 18.5-29.9. Participants were observed for one week. 'It was a usual week in the life of the participants, with similar diet and physical activity to the previous weeks', the authors of the publication explain.

The activity level of participants was measured with special sports watches. They also documented their entire diet. After one week, during a follow-up visit, stool samples delivered by participants were collected for gut microbiota testing.

It turned out that people on a balanced diet with an average daily consumption of at least 500 g of vegetables and fruit and at least 10 g of nuts had an 86% lower risk of COVID-19 compared with those whose diet was not balanced and who consumed lower amounts of these products

According to the US Centers for Disease Control and Prevention, the persons from the age group of 20–44 years account for 20% of hospitalised patients with COVID-19, of whom 12% required admission to the intensive care unit. While young adults typically show a less severe course of the disease, they also develop symptoms. In addition, their sickness is associated with a significant economic burden.

In turn, according to the Nationwide Seroepidemiological Study COVID-19 conducted in Poland, 29.5% of people aged 20–39 years contracted COVID-19.

Where did the idea to search for links between COVID-19 and diet? According to the scientists, literature data suggest that the morbidity of COVID-19 is associated with increased levels of inflammatory mediators, and the severity of symptoms is linked with hyperactive immune response, due to increased levels of cytokines and chemokines. The connection between diet and the immune system is well established, and available evidence shows that adequate nutrition is necessary for proper immune function.

Other important issues that inspired Krakow scientists to look at diet included the previously suggested relationship between intestinal dysbiosis (disrupted function and imbalanced composition of gut microbiota) and respiratory infections, as well as the recently reported link between the intake of omega-3 fatty acids, vitamin D, probiotics, multivitamin supplements, and a lower risk of positive test results for SARS-CoV-2.

'Our results confirm that nutrition is a particularly important issue in the prevention of COVID-19, as stated by some clinicians and nutritionists since the onset of the pandemic', th aquthors write. 'Beginning in spring 2020, medical experts, including Dr Zbigniew Martyka and Professor Piotr Kuna, have underlined the importance of optimal immune function (achieved via proper nutrition and physical activity) in the context of reducing the risk of SARS-CoV-2 infection and COVID-19'.

They add that there were more such suggestions in the scientific literature. The results of Dr. Jagielski's research confirm these reports.

They show, for example, that the nutrition of people with a history of COVID-19 was characterized by a significantly lower energy value, water content, and intake of plant protein, carbohydrates, and fiber, compared with people without a history of COVID-19. The researcher explain that the consumption of a certain amount of protein with high biological value is crucial for the optimal production of antibodies. However, protein derived from foods such as processed meat and cheese promote lipogenesis and increasing inflammation. On the other hand, the anti-inflammatory properties of plant-based proteins are well recognized.

'In our study, people who did not develop COVID-19 showed a higher dietary intake of plant-based protein than those with COVID-19 (…).People with a history of COVID-19 consumed lower amounts of groats and rice, fruit and vegetables (including garlic), nuts, and legumes. They had a lower dietary intake of water, plant protein, dietary fiber, potassium, magnesium, iron, zinc, copper, vitamin E, thiamin, vitamin B6, and folates', the scientists write.

Since we still have no fully effective methods of combating COVID-19, it is important - according to the authors - to use of all available ways to reduce the risk of developing the disease. Vased on their results, they recommend moderate daily physical activity, maintenance of normal body weight, and consumption of the appropriate amounts of red and green peppers, broccoli, onions, garlic, carrots, tomatoes, cauliflower, sauerkraut, oranges, grapefruits, apples, plums, buckwheat groats, oatmeal, whole meal bread, yoghurt, curdled milk, nuts, seeds, pulses, ginger, fish, lean meat, poultry, eggs, olive and rapeseed oil, bee products, drinking mineral water, green tea, as well as cod liver oil as a source of vitamin D, and omega 3 fatty acids.

'We can hypothesize that if the above results translated to the entire population of young people without comorbidities, it could be expected that the number of people contracting COVID-19 would decrease significantly, which would provide health, economic, social, and psychological benefits', the researchers emphasize.

Importantly, the results may have a wider application than those related to the ongoing pandemic. 'We currently do not know when medicine will deal with SARS-CoV-2 infection. Moreover, other viruses may cause new epidemic outbreaks in the future. Therefore, it is important to emphasize the role of proper nutrition for optimal immune function', they write.

Physical activity and a proper diet ensuring the supply of all necessary nutrients should form the basis of health maintenance. This applies even to cases where there is access to vaccinations or effective pharmacotherapy, given that vaccinated people are still at risk of SARS-CoV-2 infection and the development of COVID-19.

'Proper nutrition, physical activity, and maintenance of normal weight ensure optimal function of the immune system and are thus necessary to maintain health. Therefore, their importance as a preventive measure cannot be marginalized. As nutritionists, dietitians, and medics, we call for immediate social campaigns educating the public on how to eat properly and maintain normal weight to ensure optimal immune function, especially in the context of SARS-CoV-2 infection and COVID-19', they conclude.

Link to the source article: https://www.mdpi.com/2072-6643/14/2/350

PAP - Science in Poland, Katarzyna Czechowicz

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