As the COVID-19 turns into a national crisis in Kenya, individual counties in the country are taking some of the necessary measure to contain the pandemic. Most of the counties are engaging the national government in the acquisition of necessary interventions for preparedness for a possibility of the outbreaks in the regions, but very few are concerned with the food and nutrition of their natives, with Mombasa County being in the frontline as reported in the local dailies. However, this would contribute to the levels malnutrition amongst the population in Kenya. As documented by the World Health Organization (WHO) nutrition is a critical determinant of the immune responses and malnutrition the most common cause of immunodeficiency worldwide. Further, WHO with bodies such as National Center for Biotechnology Information (NCBI) and Kenya Medical Research Institute (KEMRI) outlines the role of body’s immune system is to protect the host against infection from pathological microbes, to clear damaged tissues, and to provide constant surveillance of malignant cells that grow within the body. Also, the immune system develops appropriate tolerance to avoid unwanted response to healthy tissues of self or harmless foreign substances.
There are considerable factors among individuals in the dynamism of their immunological responses, owing to nutrition, lifestyle, genetics, environment, and the interface of these factors. Nutrition is key and impacts the body’s immune system. Just as other bodily systems, the immune system depends on adequate nutrients to function properly. It is well-documented by the NCBI that nutritional status is closely associated with immunity and host resistance to infection. There is bantam argument that deficiency in both macro – and micro – nutrients impairs the immunological responses, but the good news is that this can be reversed by nutrient repletion. Nutritional deficiencies are still prevalent in Kenya, following UNICEF Kenya Humanitarian Situation Report by February 2019 there were 1.1 million food insecure people in Kenya, up from 700,000 people in 2018. Therefore, nutritional deficiencies due to food insecurity in Kenya are among the main contributors to a high incidence of morbidity and mortality from infectious diseases eg the current COVID-19. Even in developed countries such as the USA and Italy where general nutritional deficiencies are rare, nutrition issues such as specific nutrient deficiencies, less ideal diet composition, and excess calorie consumption are still a challenging reality among their populations. In Kenya nutritional deficiencies are particularly important in children under the age of five years, women of the reproductive age (15 – 49 years) and the elderly population due to a variety of physiological factors such as dependency, disease, poor food selection, and lower socio-economic status. Although it is established that nutritional deficiency or insufficiency needs to be improved to ensure proper immunological, growing proof proposes that for certain nutrients, increased intake above currently recommended levels may help optimize immune function including improving defence function and thus resistance to infection, while maintaining tolerance.
Research has shown that fruits and vegetables provide nutrients like beta carotene (Vitamin A precursors), vitamin C and vitamin E that can boost the immunological responses. Because most of the vegetables and fruit and other plant based foods are rich diets in antioxidants they help reduce the oxidative and inflammatory stress as documented by Eichelmann and colleagues, 2016 in the Journal Obesity reviews. Firstly, beta-carotene a powerful antioxidant predominant in vitamin A rich vegetables and tubers (pumpkin, carrot, squash, or orange fleshed sweet potato and red sweet pepper) green leafy vegetables (amaranth, cassava leaves, Sukuma wiki, spinach and vitamin A rich fruits (ripe mango, apricot, ripe papaya, dried peach, and 100% fruit juice made from these). Beta-carotene can reduce inflammation and boost immunological functions by increasing disease-fighting cells in the body. Secondly, vitamin C and E are antioxidants that help the to destroy free radicals and support the body natural immune response. Key sources vitamin C are citrus fruits (oranges and lemons), strawberries, mangoes, red peppers, broccoli, amaranth, cassava leaves, Sukuma wiki, spinach while vitamin E sources are nuts, spinach, Sukuma wiki, seeds and broccoli. Thirdly, Grant WB and colleagues, 2020 in the journal nutrients have outlined evidence that vitamin D supplementation could reduce risk of influenza, COVID-19 infections and deaths, by reducing production of pro-inflammatory compounds in the body. Likewise, increased blood levels of vitamin D has been linked to prevention of other chronic diseases including tuberculosis (TB), hepatitis and cardiovascular disease. Sources include cereals, milk, egg, Organ Meat (liver, kidney, heart or other organ meats or blood-based foods) and Flesh Meats (beef, pork, lamb, goat, rabbit, chicken, duck etc). Fourthly, zinc predominant in nuts, pumpkin seeds, sesame seeds, beans and lentils, is a mineral that can boost white blood cells, which defend against invaders.
Aside from the commonly known nutrients, there are a wide variety of non-nutritive phytochemicals (such as phenols and flavonoids) and functional foods (probiotics and fibre). They are not essential for maintaining normal cell metabolism and function thus do not have recommended levels of intake in dietary guidelines. Despite this, many phytochemicals and functional foods have been shown to have beneficial effects on immune function. While there are many other nutrients and non-nutritive categories that are also known to affect immune function, included are only a few as representative.
Despite, this evidence that nutrition and other lifestyle measures influences the immunological strength and susceptibility to infectious disease. Whether these measures do or do not influence susceptibility to COVID-19 or its clinical course is not yet known. Henceforth there is every motivation to put what we do know about foods and immune defences to use in addition to the everyday preventive measures- such as handwashing, avoiding contact with sick people, good hygiene as per the MoH and WHO guidelines – can go a long way in reducing your risk for viruses, bacteria and other pathogens.
Chadwick Digo, RNS, CPHN (Nutrition Scientist & Adjunct Lecturer, Department of Human Nutrition, Egerton University) firstname.lastname@example.org