If COVID made us realise something, it is that our immune systems might not always be ready to fight foreign bodies. The more compromised they are, the higher is our susceptibility to infections.
Our immune system needs to be retrained periodically to recognise new pathogens, by way of vaccines and boosters. And it needs to be always kept healthy and active.
However, there is no single way or food item that can boost this complex network. What it needs is a balanced diet with a combination of vitamins and minerals and a healthy lifestyle.
Mumbai-based nutritionist Harshita Kalra explains, “Every nutrient is important to our body and has its benefits. Micronutrients like Vitamins C, E, A, D as well as other dietary components have specific roles in maintaining the immune system and fighting infections or diseases.”
Incorporating all these nutrients in our daily diet is the best way to nourish the immune system.
Fighting inner battles
The immune system is vital as it protects the human body from germs and cell changes that cause illnesses. It is done by:
- Eliminating known harmful bacteria, viruses, fungi and parasites from the body
- Memorising new viruses once they enter the body
- Reacting to harmful substances in the environment – when we develop an allergy
- Fighting changes that cause disorders in the body – such as cancer cells
The immune system identifies antigens or foreign bodies, separates the harmful ones like germs from the innocuous ones like food; and activates itself according to the extent of involvement required. Its response could be an allergy to fight antigens, or an inflammation to fight pathogens.
However, when the system malfunctions, it starts destroying healthy cells, and this behaviour of the body is called autoimmune disorder.
Role of micronutrients
A review of the relationship between micronutrients and the immune system, published in the journal Nutrients in January 2020, states that Vitamins A, D, C, E, B6 and B12 need the presence of folate, zinc, iron, copper and selenium to ensure a proper immune response whenever required.
In our body, the innate immune system is the first line of defence against pathogens, and the adaptive system remembers and recognises pathogens to create their antibodies. Both systems require adequate amounts of these micronutrients for their optimal functioning.
The study also indicates that the strongest support to the immune system comes from Vitamins C, D and zinc.
The gut reaction
“Over 70 per cent of our immune cells are in our gut. A balance between good and bad gut bacteria is crucial for boosting our immune cells,” says nutritionist Katrina Cox, of Rhode Island, USA. The food we ingest can also carry pathogens, she explains.
The gut microbiome comprising thousands of microorganisms is a major producer of antimicrobial proteins that kill harmful bacteria. What we eat determines the kind of microbes that populate the gut. One way of maintaining the dominance of healthy, germ-killing microbes is to include prebiotics and probiotics in the diet. They release short-chain fatty acids which activate the cells in the immune system.
Multiple options to eat
In a 2022 study published in Nutrients, the team underlines the role of fermented foods in creating a favourable environment for the gut bacteria – a reason for including them in human diet.
The study says fermented probiotics like yogurt, kefir, and kombucha should be part of our daily diet to boost gut health and immunity.
It further suggests eating Vitamin C-rich citrus fruits like orange, lime, and grapefruit; besides papaya, kiwi, and guava.
Among vegetable sources are eggplant (brinjal or aubergine), bell peppers, beetroots, spinach, and cauliflower.
The UK’s National Health Service (NHS) recommends 49 mg of Vitamin C per day for adults. As this vitamin cannot be stored by the body, we need to ensure its daily intake.
For fish and meat eaters, the daily doses of required Vitamin D and zinc can come from tuna, salmon, sardines and red meat or liver. Zinc can also be found in cheese, chickpeas, lentils and peanuts.
Keeping inflammation at bay
Katrina Cox recommends consuming foods like ginger, garlic, turmeric, soy, seafood, berries, and grapes that are known to have anti-inflammatory benefits. She says, “While mild inflammation might be the immune response to heal your body, over-inflammation will have the opposite effect.”
According to Harshita Kalra, “Building immunity against disease is a process of being consistent with certain habits and ensuring our bodies gets all the nutrients they need.” She emphasises that a balanced diet, daily exercise, and most importantly, avoiding junk or processed food or food high in saturated fats can significantly boost our immune system.