September 22, 2022
Immunity is a defence system consisting of a vast network of cells and tissues in our body which provides protection against disease-causing microbes. This is critical for our survival. In the case of the prevailing Covid-19 pandemic, we are beginning to read reports that state the correlation of NCDs – non-communicable diseases to the fatalities of Covid-19. Individuals in certain pre-existing illnesses like diabetes, hypertension, cardiovascular disease, and respiratory issues are at a higher risk of having Covid-19 complications.
We have well established data stating that our complex immune system requires several micronutrients that have vital, often interdependent roles at every phase of the immune response. It has been noted that even borderline deficiencies in certain nutrients tend to impair the immune system.
Moreover, deficiency of a single nutrient can alter the body’s immune response as well. Based on a variety of clinical data, Proteins, Vitamins A, B6, B12, C, D, E, Folate, Zinc, Iron, Copper, Selenium, Magnesium, Omega-3 and Probiotics, are particularly important in boosting the immune response.
These nutrients help the immune system in several ways:
work as antioxidants to protect healthy cells,
sustain growth and activity of immune cells,
Malnutrition or a diet lacking in one or more nutrients can impair the production and activity of immune cells and antibodies.
Eating enough nutrients as part of a varied diet is required for the health and function of all cells, including immune cells. Certain dietary habits may better prepare the body for microbial attacks and excess inflammation, but it is unlikely that individual foods offer special protection. Each stage of the body’s immune response relies on the presence of many micronutrients.
Proteins, more specifically amino acids, are used for cell-specific production of components with great physiological importance. Protein deficiency is associated with impaired immunity among other issues. Individual amino acids have been shown to influence components of the immune system by enhancing T-cell response.
Products in which Protein is naturally found: Cereals, Grains, Pulses, Dairy & Dairy products, Nuts (whole nuts, nut butter, nut milk), Seeds, Health Food Drinks, Soy products (tofu, soy milk, soy nuggets), Eggs, Meat.
Recommended Daily Allowance: 0.8 – 1.0 g/kg/day
Vitamin A has a central role in enhancing immune function and plays regulatory roles in cellular immune responses. It also forms an integral part of epithelial tissues and mucous membranes which form the first line of defence against infections.
Products in which Vitamin A is naturally found: Red, orange, and yellow coloured fruits and vegetables, dried fruits, Dairy & Dairy products (milk, Dahi, yogurts, fermented dairy beverages), and Egg yolk. Many foods are also fortified with Vitamin A. This makes Vitamin A available in food sources beyond its natural sources, like Milk, Dahi, Dairy Products, Multigrain Attas, Breakfast Cereals, Ready-to-cook-&-eat products, Edible Oil & Health Food Drinks.
Recommended Daily Allowance: 600 mcg /day (retinol)
Vitamin D plays a regulatory role in immune response and helps in the maturation of immune cells. Laboratory studies show that Vitamin D can reduce cancer cell growth, help control infections and reduce inflammation.
Products in which this nutrient is naturally found: Dairy & Dairy products, Egg yolk, and fatty fish. Like Vitamin A, many foods are also fortified with Vitamin D. This makes Vitamin D available in food sources beyond its natural sources, like Milk, Dahi, Edible Oil and Health Food Drinks.
Recommended Daily Allowance: 10 mcg/day
Vitamin E is primarily effective against infections due to its potent antioxidant functions. It enhances the activity of white blood cells and helps them to destroy foreign cells, thereby enhancing resistance against infectious agents.
Products in which this nutrient is naturally found: Vegetable Oils, Nuts (whole nuts, nut butters, nut milks), Seeds (sunflower seeds, pumpkin seeds, melon seeds, etc.)
Recommended Daily Allowance: 15 mcg/day
Vitamin C acts an antioxidant and protects cells from oxidative damage from free radicals. It provides protection against disease-causing bacteria and viruses. It also supports the immune cells to fight microbes, improving the body’s immunity against them. Moreover, Vitamin C plays an important role in the healing of sites affected by the infection.
Products in which this nutrient is naturally found: Guava, Amla, Tomatoes, Citrus fruits like orange, lemon, sweet lime, fruit & vegetable beverages. Vitamin C fortification commonly seen in Breakfast Cereals
Recommended Daily Allowance: 40 mg/day
Studies suggest that Vitamin B6 deficiency affects the immune response. Growth and maturation of immune cells are altered by deficiency, immune responses are reduced, and antibody production may be indirectly impaired.
Products in which this nutrient is naturally found: Whole grains (wheat, rice, millets, quinoa, etc.), Wholegrain and Multigrain flour, Bread, Soy & Soy products, and Peanut butter.
Recommended Daily Allowance: 1.7 mg/day
Human studies have demonstrated various immunity-altering effects of Vitamin B12. It plays a role in immunity by enhancing the activity of Immune cells like Lymphocytes and Natural Killer cells.
Products in which this nutrient is naturally found: Meat and Meat products, Egg, Dairy & Dairy Products (milk, dahi, cheese). Vitamin B12 is also found in Fortified Breakfast Cereals and Health Food Drinks.
Recommended Daily Allowance: 1 mcg/day
Inadequate levels of folic acid and B12 can change our immune responses through a variety of processes as well as interfere negatively with the activity of immune cells.
Products in which this nutrient is naturally found: Whole pulses and legumes, Green leafy vegetables, nuts, and seeds. Folate is also found in Fortified Breakfast Cereals and Health Food Drinks.
Recommended Daily Allowance: 200 mcg/day
Research studies show that low iron levels affect the cascade of adequate immune response. It is required for immune cell production and growth, particularly lymphocytes, which are related to the initiation of specific responses to infection.
Products in which this nutrient is naturally found: Pulses and Pulse-based products (beans, sprouts, dals), Nuts & Seeds, Dried Fruits, Meat, and Egg. Iron is also found in fortified and enriched Bread, Breakfast Cereals, and Health Food Drinks.
Recommended Daily Allowance: 19-21 mg/day
Research shows that zinc affects multiple aspects of the immune system. It is crucial for the normal development and function of immune cells. Zinc also is an antioxidant and has anti-inflammatory actions. Zinc insufficiency leads to changes in immune cell numbers and activities, which results in increased susceptibility to infections and the development of inflammatory diseases.
Products in which this nutrient is naturally found: Whole grains (wheat, rice, millets, quinoa, etc.), Wholegrain and Multigrain Flours, Bread, Dairy & Dairy Products, Meat & Meat products, Nuts (whole nuts, nut butter, nut milk), Seeds. Fortified Breakfast Cereals and Health Food Drinks are fortified with zinc.
Recommended Daily Allowance: 12 mg/day
Magnesium has a role to play in innate as well as acquired immunity. Its deficiency is associated with impaired immune function as the production and activity of phagocytes (immune cells which destroy microbes) are affected by the availability of Magnesium.
Products in which this nutrient is naturally found: Dark Chocolate, Whole grains (wheat, rice, millets, quinoa, etc.), Wholegrain and Multigrain Flours, Bread, Dairy & Dairy Products, Pulses and Pulse-based products (beans, sprouts, dals), Nuts & Seeds.
Recommended Daily Allowance: 340 mg/day
Selenium is an important part of the body’s antioxidant system, protecting the body against oxidative stress. Selenium plays a key role in the functioning of the immune system. This can be attributed to its role in regulating oxidative stress and excessive immune responses as well as chronic inflammation.
Product categories in which this nutrient is naturally found: Whole grains (wheat, rice, millets, quinoa, etc.), Wholegrain and Multigrain Flours, Bread, Dairy & Dairy Products, Meat & Meat products naturally contain good amounts of selenium. Some Health Food Drinks are fortified with selenium.
Recommended Daily Allowance: 40 mcg/day
Copper deficiency leads to reduced formation of immune cells. This cements the fact that copper is essential for effective immune response and inadequate levels leads to increased susceptibility to bacterial infections.
Products in which this nutrient is naturally found: Whole Grains, Beans, Nuts, and Dried Fruits are good sources of copper.
Recommended Daily Allowance: 2000 mcg/day
Omega 3 fatty acids play major roles in activation of immune cells. Its role in immune function can also be attributed to its antioxidant properties.
Products in which this nutrient is naturally found: Nuts (walnuts), Seeds (Flaxseed, Chia seeds, Mustard seeds), Fatty Fish, Edible oils (Mustard Oil, Flaxseed Oil, Soybean Oil, Canola Oil). Omega-3 is also found in omega-fortified Dairy and Dairy products, Breakfast Cereals and Health Food Drinks.
Recommended Daily Allowance: 2 g/day
Probiotics regulate immune responses by influencing the functions of immune cells. The good microbes found in probiotic food maintain the balance of bacteria and suppress the growth of potentially disease-causing bacteria in the gut. The gut has a direct effect on our immune system, hence consuming fermented foods can help maintain your health in the gut. Product categories in which this nutrient is naturally found: Fermented Dairy products (Dahi, Yogurt, Kefir, Lassi), Kombucha, Pickles, Natural Cheese, Sourdough bread, Miso, Tempeh.
There is no evidence that any specific food is directly seen to combat or cure viruses or bacteria, but it is recommended to build your immunity with the help of the mentioned nutrients. Excessively consuming food/food items rich in these nutrients is not advised but focus should be that you meet your daily recommended needs of the above nutrients to stay protected.
As certain nutrients help in building immunity, there are a few nutrients that suppress our immunity making us more susceptible to diseases and illnesses.
Diets that are not diverse, limited in variety and lower in nutrients, such as certain ultra-processed packaged foods, can negatively affect a healthy immune system. It is also believed that a diet high in refined sugar, fat and sodium and low in fruits and vegetables can promote instabilities in healthy intestinal microorganisms, resulting in chronic inflammation of the gut, and associated suppressed immunity.
Consuming excess sugar has been shown to suppress the immune system by negatively impacting the function of phagocytes (immune cells that engulf and destroy microbes). Excess sugar consumption has also been liked to increased inflammatory components, which contribute to inflammatory diseases like cancer.
Product categories in which this nutrient is found: Sugar-sweetened beverages like Fruit & Vegetable Juices, Flavoured Milk, Flavoured Drinks, Carbonated Beverages, Flavoured Dairy products, Packaged Sweets (mithai) & Desserts, Bakery Products, and Sugar-sweetened Breakfast Cereals.
Daily Values: Not to exceed 50 g/day
Increased saturated fatty acids in the diet elicit a proinflammatory response that contributes to immune dysfunction that worsens infection control. Both the concentration and composition of dietary fat (saturated fatty acids as well cholesterol) can alter the serum lipoprotein profile, which influences the activity of the immune cells. Dietary Fats have the ability to directly affect immune cells function by changing the lipid composition of the immune cells.
Product categories in which this nutrient is found: Packaged Sweets (mithai) & Desserts, Bakery Products, Hydrogenated Vegetable Fats, Savoury Snacks & Namkeen.
Daily Values: Saturated Fat not to exceed 22 g/day; Trans Fat not to exceed 2 g/day
Studies suggest that a high-salt diet can directly affect immune cells resulting in a proinflammatory immune response which causes more harm than good. Excess salt also causes increased levels of glucocorticoids, which have immunosuppressant properties.
Product categories in which this nutrient is found: Bakery Products, Savoury Snacks (Chips, Wafer, Crackers and more) & Namkeen, Savoury Breakfast Cereals.
Daily Values: Sodium not to exceed 2000 mg per day (=5g Salt /day)
Eat a balanced diet with grains, legumes, fruits and vegetables, and dairy products.
Minimize consumption of packaged foods that are high in fat, sugar, and salt.
Avoid smoking and alcohol.
Get 7-8 hours of sleep.
Aim to manage stress. Take up a hobby, meditate or talk to a loved one.
Perform moderate intensity exercises like running, jogging, and cycling.
Wash hands throughout the day; when coming in from outdoors, before and after preparing and eating food, after using the toilet, and after coughing or blowing your nose.
Breda Gavin-Smith (2020). The Role of Nutrition in the Immune System (Online). Available on https://sightandlife.org/blog/nutrition-immunity-part-ii/
Fast food fever: reviewing the impacts of the Western diet on immunity, Ian A Myles, 2014.
Nutrition and Immunity, Harvard School of Public Health
Saayma Rizvi (BSc in Food Science and Nutrition)