5. Vitamin A
Vitamin A maintains the structure of the cells in the skin, respiratory tract and gut. This forms a barrier and is your body’s first line of defense. If fighting infection was like a football game, vitamin A would be your forward line.
We also need vitamin A to help make antibodies which neutralist the pathogens that cause infection. This is like assigning more of your team to target an opposition player who has the ball, to prevent them scoring.
Vitamin A is found in oily fish, egg yolks, cheese, tofu, nuts, seeds, whole grains and legumes.
Further, vegetables contain beta-carotene, which your body can convert into vitamin A. Beta-carotene is found in leafy green vegetables and yellow and orange vegetables like pumpkin and carrots.
6. B vitamins
B vitamins, particularly B6, B9 and B12, contribute to your body’s first response once it has recognized a pathogen.
B6 is found in cereals, legumes, green leafy vegetables, fruit, nuts, fish, chicken and meat.
B9 (folate) is abundant in green leafy vegetables, legumes, nuts and seeds and is added to commercial bread-making flour.
B12 (cyanocobalamin) is found in animal products, including eggs, meat and dairy, and also in fortified soy milk (check the nutrition information panel).
7. Vitamins C and E
When your body is fighting an infection, it experiences what’s called oxidative stress. Oxidative stress leads to the production of free radicals which can pierce cell walls, causing the contents to leak into tissues and exacerbating inflammation.
So the role of vitamin C here is a bit like cleaning up the football ground after the game.
Good sources of vitamin C include oranges, lemons, limes, berries, kiwifruit, broccoli, tomatoes and capsicum.
Vitamin E is found in nuts, green leafy vegetables and vegetables oils.
8. Vitamin D
Some immune cells need vitamin D to help destroy pathogens that cause infection.
Although sun exposure allows the body to produce vitamin D, food sources including eggs, fish and some milks and margarine brands may be fortified with Vitamin D (meaning extra has been added).
Most people need just a few minutes outdoors most days.
People with vitamin D deficiency may need supplements. A review of 25 studies found vitamin D supplements can help protect against acute respiratory infections, particularly among people who are deficient.
9. Iron, zinc, selenium
We need iron, zinc and selenium for immune cell growth, among other functions.
Iron is found in meat, chicken and fish. Vegetarian sources include legumes, whole grains and iron-fortified breakfast cereals.
Zinc is found in oysters and other seafood, meat, chicken, dried beans and nuts.
Nuts (especially Brazil nuts), meat, cereals and mushrooms are good food sources of selenium.