Your immune system responds most sensitively to subtle changes in nutrition status. Having an impaired immune system opens the way for infectious diseases, which raises nutrient requirements and lowers food intakes – which nutrition status then again suffers further.
There are two lines of immune defences in our bodies. First line is innate immunity which is combines physical and biochemical barriers with non-specific leukocytes-mediated cellular response to defend against pathogens(germs/bugs). Innate immunity is non-specific and fast.
If pathogens manage to avoid innate defences, adaptive, specific response is triggered mediated by T & B cells lymphocytes, which produce antibodies to target and destroy the pathogens. Adaptive immunity is specific and slow.
There is a variety of micronutrients to help sustain a healthy immune system, they include; vitamins A, C, D, E, B2, B6, B12, folate, beta carotene, iron, selenium and zinc.
Below is a list of these micronutrients and sources you can get these from.
VITAMIN A: Fortified milk, cheese, cream, butter, eggs and liver.
BETA CAROTENE: Spinach, other dark leafy greens, broccoli and deep orange fruits & vegetables (carrots, sweet potatoes, pumpkins).
VITAMIN C: Citrus fruits, cabbage type vegetables, dark green vegetables, rockmelon, capsicum, strawberries, lettuce, tomatoes, potato, papayas and mangoes.
VITAMIN D: Synthesised within the body with the help from the sun, fortified milk, butter, veal, beef, egg yolk, liver, fatty fish and their oils.
VITAMIN E: Polyunsaturated plant oils, leafy green vegetables, wheat germ, whole grains, liver, egg yolks, nuts, seeds and fatty meats.
VITAMIN B2: Milk products, whole grains, fortified or enriched grain products and liver.
VITAMIN B6: Meats, fish, poultry, potato & other starchy vegetables, legumes, non-citrus fruits, fortified cereals, livers and soy products.
VITAMIN B12: Foods of animal origins and fortified cereals.
FOLATE: Fortified grains, leafy green vegetables, legumes, seeds and liver.
IRON: Red meat, fish, poultry, shellfish, eggs, legumes and dried fruits.
SELENIUM: Seafood, meat, wholegrain, fruits and vegetables.
ZINC: Protein containing foods, red meats, shellfish, whole grains and some fortified cereals.