The role of plant-based diet in protecting the immune system during the COVID-19 pandemic


Judit  Molnár* and Mahendra, Pal**

The resurgence of COVID-19 pandemic highlighted the concern among the people for their good health by taking immune boosting foods that can protect from this life threatening disease. The beneficial and disease preventing effects of a healthy diet are addressed by several researchers in their publications. Due to COVID-19 pandemic, the plant based diet may also play an increased role to boost the immunity of the body and thus may help in its prevention. Some of the fruits and vegetables like oranges, lemons, strawberries, kiwis, black berries, papaya, grapefruits, avocado, pineapple, peach, guavas, grapes, apples, red bell peppers, mangoes, bananas, watermelon, gooseberry, cabbages, Brussels sprouts, broccoli, tomatoes, potatoes, green peas, carrots, spinach, ginger, turmeric etc., are rich sources of minerals, vitamins, antioxidants and polyphenols that support the immune system of the body and also promote overall health and wellness of the human beings. The strong immune system of body may fight against the infections and thus help to protect the health.

Keywords: Antioxidants, COVID-19 pandemic, Fruits, Immune system, Minerals, Plant-based diet, Vegetables, Vitamins

Since the identification of a novel human coronavirus, severe acute respiratory syndrome coronavirus  2(SARS-CoV-2 in Wuhan city of China in December 2019, the virus has made its way across the globe affecting  over 200 countries including India. SARS-CoV-2 has infected sexes, all age groups, and all ethnicities in developed as well as developing nations of the world. COVID-19 pandemic has emerged as a global disaster due to significant morbidity as well as mortality all over the world (Coutino and Zandi, 2021; Mannucci et al., 2020; Pal et al., 2020). Currently, there are 184,573,165 cases and 3,993,577 deaths due to COVID-19 worldwide. In India, presently, COVID -19 is responsible for 29,700,313 cases and 381,931 deaths (M. Pal Personal Communication).

The prevention is considered better than cure. The most effective method of prevention currently practiced is the use of a safe and potent vaccine against COVID-19. However, the use of other control methods, such as healthy eating, is also very important (Jaeger et al., 2021; Suarez et al., 2021). Within a healthy diet, many types of diets are prevalent in different regions of the world. The consumption of healthy diet provides various essential nutrients that are required to prevent the diseases that affect our health. The plant based diet, including the vegetables and fruits have got immense antioxidant activity that scavenges acid free radicals and reduce the oxidative stress and also increase resistance against many infectious agents that cause significant morbidity and mortality in susceptible people throughout the world (Vinayraj, 2020). It is pertinent to mention that vitamins, minerals, and antioxidant contents of the vegetables and fruits help to fight viral infections (Cömert et al., 2020). 

The plant based diets are provided in a variety of forms by food companies to provide a complete nutrient. In addition to fresh, unprocessed products (fresh fruits and vegetables), processed foods and hot ready meals are also included. As a result, many foods of animal origin can be substituted, such as meat, milk, and dairy products. A wide variety of plant-based products, plant-based drinks, plant-based yogurt and other dairy products have also appeared on the shelves of companies. In addition, tofu can be used to replace the meat. Hot ready meals can be made from the plant-based products in the same way (fried, cooked, fried) as from products of animal origin. In addition, fresh salads, fresh vegetables, and fresh fruits are also recommended (Essen, 2021; Williams and Patel, 2017). The manuscript, therefore, summarizes the positive properties of the vegetables and fruits, paying attention to their role in healthy diet.

The role of vegetables and fruits in the plant-based diet
Food is indispensable for the survival of human beings (Pal, 2020).Good nutrition plays a key role to boost immune systems that resist the body against the infection. It is well recognized that an individual with a weak immunity is easily susceptible to the infections including COVID-19. It is pertinent to mention that immune system needs energy, macro and micro nutrients for a good immune response. Hence, good nutrition plays a vital role to support the immune system and a good immune response can decrease the risk of infectious diseases (M.Pal Personal Communication).  According to the recommendations of a healthy diet, it is advised to consume the fruits and vegetables daily in the most varied form (Han et al., 2008; Marles, 2017). During the consumption, it is advisable to monitor the freshness, and the vitamin and mineral content of the food. A large variety of  the fruits and vegetables like orange, pear, mulberry, plum, bread fruit, apricot, pear, grape fruit, persimmon, cherry, grapes, papaya, strawberry, mango, pineapple, watermelon, pomegranate, banana, apple, lemon, carrot, turnip, radish, scallion, ginger, spinach, snap beans, tomato, rutabaga, yam, sweet potato  etc., are consumed globally. These have a number of properties that contribute to the maintenance of good health, and also in the prevention or treatment of diseases (M. Pal Personal Communication). 

-Most vegetables and fruits contain large amounts of water, so their consumption also helps in hydration (Khandpur and Gogate, 2015).
-The fiber contents of vegetables and fruits are high and therefore, they aid in the digestion and also reduce the development of the cardiovascular disease (Sucupira et al., 2020).
-The vitamins and minerals contents of fruits and vegetables are very diverse, so they support the immune system of our body to fight against the infection (Augustin et al., 2020).
-The fruits and vegetable are the most significant sources of antioxidants, which reduce the development of tumors and increase the protective power of the immune system (Hegazy et al., 2019).
-Polyphenols are the naturally occurring compounds that are present in several plant based diet like orange, mango, gooseberry, grapes, ginger, turmeric etc. The consumption of polyphenol rich diet provides protection against infectious agents (Vinayraj, 2020).

The manuscript presents the role of various fruits and vegetables in supporting the immune system, including the plant-based diet. The liquid, fiber, antioxidant, vitamin and mineral contents of the vegetables and fruits also contribute to their positive effects. Furthermore, thanks to their useful content values, vegetables and fruits help in digestion, reduce the development of cardiovascular diseases, and support the immune system. The manuscript focuses on the importance of plant-based diets and recommendations for consuming the vegetables and fruits daily in moderate quantity as a part of our diet. It is emphasized that immunity boosting foods including the fruits and vegetables must be included in the daily diet to keep safe and healthy during COVID-19 pandemic. Furthermore, it can also help to strengthen the immune system and fight the pandemic through good nutrition.Author’s Bio

*Dietitian, MSc in Food Safety and Quality Engineering; Ph.D. in Food Sciences - 1 1/9 Palánkutca, 9200 Mosonmagyaróvár, Hungary (e-mail:
**Narayan Consultancy on Veterinary Public Health and Microbiology- Anand-388001, Gujarat, India 
**Corresponding Author: Prof.Dr.Mahendra Pal, Founder Director of Narayan Consultancy on Veterinary Public Health and Microbiology, Aangan, Jagnath Ganesh Dairy Road, Anand-388001, Gujarat, India

We are very thankful to Prof. Dr. R.K. Narayan for his suggestions during the preparation of manuscript and Anubha Priyabandhu for computer help.

Contribution of authors
Both the authors contributed equally. They read the final version, and approved it for the publication.

Conflict of interest
The authors declare that they do not have conflict of interest.

Source of financial grant
There was no financial support for this manuscript.

1.Augustin, M. A., Sanguansri, L., Fox, E. M., Cobiac, L. and Cole, M. B. (2020): Recovery of wasted fruit and vegetables for improving sustainable diets. Trends in Food Science and Technology, 95:75-85.

2.Coutino, A. and Zandi, M. (2021): Global loss of production capacity caused by the COVID-19 pandemic. Journal of Policy Modelling, 43:493-502.

3.Cömert, E. D., Mogol, B. A. and Gökmen, V. (2020): Relationship between colour and antioxidant capacity of fruits and vegetables. Current Research in Food Science, 2:1-10.

4.Essen von, E. (2021): Young adults transition to a plant-based diet as a psychosomatic process. A psychoanalytically informed perspective. Appetite, 157:1-10.

5.Han, J.H., Yang, Y.X.and  Feng M.Y. (2008): Contents of phytosterols in vegetables and fruits commonly consumed in China. Biomedical and Environmental Sciences, 21:449-453.

6.Hegazy, A. K., Mohamed, A. A., Ali, S. I., Alghamdi, N. M., Abdel-Rahman, A. M.  and Al-Sobeai, S. (2019): Chemical ingredients and antioxidant activities of underutilized wild fruits. Heliyon, 5:1-8.

7.Jaeger, S. R., Vidal, L., Ares, G., Chheang, S. L. and Spinelli, S. (2021): Healthier eating: COVID-19 disruption as a catalyst for positive change. Food Quality and Preference, 92: 1-6.

8.Khandpur, P. and Gogate,  P. R. (2015): Effect of novel ultrasound based processing on the nutrition quality of different fruit and vegetable juices. Ultrasonics Sonochemistry,   27:125-136.

9.Mannucci, E., Nreu, B. and Monami M. (2020): Factors associated with increased all-cause mortality during the COVID-19 pandemic in Italy. International Journal of Infectious Diseases, 98:121-124.

10.Marles, R. J. (2017): Mineral nutrient composition of vegetables fruits and grains: The context of reports of apparent historical declines. Journal of Food Composition and Analysis, 56: 93-103.

11.Pal, M. (2020): Walnut: A highly nutritious food with several health benefits. Food Nutrition Open Access Dec., 3 (1). 118.

12.Pal, M., Kerosa, G. B. and Kandi, R. (2020). A knowledge update on SARS-Coronavirus-2 (SARS-CoV-2)/COVID-19 and its global public health implications. American Journal of Clinical Medicine Research, 8: 48-56.

13.Suarez, M., Carrasco, M. E. T., Morales, D., Kuritzky, A., Abril, V. and  Encalada L. (2021): Eating healthy: Distrust of expert nutritional knowledge among elderly adults. Appetite, 165:1-9.

14.Sucupira, N. R., Sousa Sabino de, L. B., Neto, L. G., Gouveia, S. T., Wilane de Figueiredo, R. and Maia, G. A., Machado do Sousa P. H. (2020): Evaluation of cooking methods on the bioactive compounds of cashew apple fibre and its application in plant-based foods. Heliyon, 6:1-9.

15.Vinayraj, B.G. (2020). Polyphenols: For an immune health benefits. Vedic Times, 5:10-11.

16.Williams, K. A. and Patel, H. (2017): Healthy plant based diet: What does it really mean? Journal of the American College of Cardiology, 70:1-3.