The immunity puzzle during COVID-19: jigsaw pieces for our immune system

Vitamin

Purpose

Food Sources

Context

A

Insufficient amount in our diet increases susceptibility to a range of infections.

Preformed - Animal foods such as liver and fat portions of dairy foods(milk, cheese, butter), egg yolk and fish.

Provitamin A and β-Carotene- Dark yellow, red, green and orange pigment in plants such as carrots, spinach, pumpkin, tomatoes, broccoli. Should be taken with 3g of fat (e.g. oil, ghee, butter) to be absorbed properly.

Cooking helps release the vitamin from plants making them available for absorption.

B2/ riboflavin

First-line host immune response against invading pathogens; helps iron absorption.

Milk and cheese.

70% B2 will be lost by exposure to sunlight.

B6/ pyridoxine

Helps in the production of antibodies and immune cells.

Whole grains (brown flour and rice, oats), pulses (chickpeas, lentils dry beans) and legumes (green beans and peas, soybeans), bananas, potatoes and meat (poultry).

B9/ folic acid

Maintain the balance of the immune system and increase resistance to infections.

Dark green leafy vegetables (spinach, cabbage, cauliflower, broccoli), citrus fruits (oranges), tomatoes, cantaloupe and legumes (green beans and peas, soybeans). Some cereals and bread are fortified with folic acid.

Folate absorption depends on its source with only 50% being absorbed from plant sources. Older people are unable to absorb enough due to low gastric acid therefore intake should be more

B12/  cobalamin

Modulates immunity against viruses and bacteria.

Only in animal food - meat, poultry, fish, milk, eggs and cheese.

Individuals who are vegan or have low gastric acid levels (older population) are unable to meet daily requirements.

C/ ascorbic acid

Reduces risk, severity and duration of upper and lower respiratory tract infections.

Requirements increase during infections.

Citrus fruits (oranges and lemons), sweet potatoes, guava, strawberries, mangoes, papaya, capsicum, broccoli.

Can be easily destroyed by heat, light and action of oxygen in the air. Cook for a limited amount of time.

D

Reduces risk of respiratory tract viral infections, therefore, improving immune functions.

'The sunshine vitamin', as its source is the sunlight. Only a few other natural sources such as fish liver oils and egg yolks (only small amounts). Sources can be oily fish like trout and freshwater river carps.

Staying indoors in a lockdown can deprive us of the daily requirements of sunlight.

It is recommended to take a supplement of 10 mcg = 400 IU (International Units). The recommended daily amount of vitamin D is 400 IU for children up to age 12 months, 600 IU for ages 1 to 70 years, and 800 IU for people over 70.

E

Potent antioxidant modulating host immune functions.

Vegetable oils (canola, sunflower, safflower) and lower amounts in olive oil and corn oil.

Also nuts (peanuts, hazelnuts and almonds), green vegetables (spinach and broccoli), sunflower seeds. Some breakfast cereals, spreads and fruit juices are fortified with vitamin E.

Benefits the elderly, may reduce the risk of upper respiratory tract infections.

Mineral type

Purpose

Food Sources

Context

Iron

Produces immune cells that attack foreign bacteria in the body.

Non-Heme Iron: spinach and legumes

Heme Iron: fish, poultry, eggs

Heme iron improves the absorption of non-heme iron, so its deficiency in diets should be monitored. Also, an acidic environment increases iron absorption (iron taken with vitamin C) while severe infection depresses it.

Zinc

Even a marginal zinc deficiency can impact immunity as it leads to increased diarrhoea and respiratory morbidity.

Sources can be seafood (shellfish-lobster, crab and oysters), meat, lamb, leafy and root vegetables, pumpkin seeds, eggs and milk.

Zinc is better absorbed from animal protein than plant protein.

Zinc supplements can interfere with iron and copper absorption and vice versa.

Older individuals with optimum zinc status have greater resistance to infections and less need for antibiotics.

Excessive zinc intake, especially from supplements, can lead to a suppressed immune system.

Selenium

An integral part of antioxidants that protects the cell and lipid membrane from oxidative damage. Selenium influences the innate and acute immune systems. Selenium partners with vitamin E.

Meat and meat products, fish, poultry, eggs and Brazil nuts.

Lacto-ova vegetarians and vegans may be at risk of deficiency.

Magnesium

Some functions of the immune system are dependent on magnesium.

Almonds, cashew nuts, green vegetables and spinach, pulses (beans, red, green, yellow and brown lentils, peas), whole grain cereals (wheat, corn, barley, oats, rye and millet).

Deficiency associated with cardiac arrhythmias and cardiac arrest.

Copper

Essential for optimal innate immune function.

Liver, seafood, nuts and seeds.

a deficiency increases susceptibility to bacterial infection.

Probiotics (live microflora) and prebiotics

'Desirable' bacteria benefiting the gastrointestinal tract by promoting the proliferation of good bacteria and limiting the development of harmful bacteria preventing the colonisation of pathogens.

Prebiotics - Bananas, onions and garlic.

Dietary sources of probiotics can be cultured milk and yogurt, cheese, pickled cabbage and tempeh.

Probiotics may be effective in treating infectious diarrhoea. Individuals with compromised immune function should not use probiotics without medical supervision.

Accurate information regarding the dosage and requirements and safety of particular supplements are still uncertain.