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The human immune system

Harriet Hunter
The human immune system

The human immune system is the body’s first barrier against potentially harmful invading pathogens - bacteria and viruses. Much like a well-oiled machine, our immune system is made up of many cogs that work together. Each supporting the role of the last. There are many factors that can affect the function of this machine we call our immune system, this includes – seasons, environment, comorbidities and nutrition.

The Human Immune System

Our immune system is governed by numerous varieties of white blood cells. These are used in the innate or adaptive immune response. The innate or non-specific immune system is made up of cells white blood cells called natural killer cells (NKs), in addition to macrophages, phagocytes, neutrophils, basophils, eosinophils and mast cells. In addition to these cells, other innate barriers for the immune system include mucous membranes, eyelashes, sweat, saliva and gastric acid. The innate response can take between 0-96 hours to work. The main process of the innate immune system is run by the white blood cell, ‘phagocyte’. This is called phagocytosis. The process begins when a ‘foreign cell’ or pathogen is detected, it then consumes and destroys the foreign cell within its own cell. In addition to the phagocytes, macrophages circulate the body and release protein-like cytokines which acts as warning signals to other cells that attach the foreign cells. Then, you have the adaptive or specific immune response. This plan of attack against invading pathogens uses T and B lymphocytes. This can take over 96 hours to take effect, or faster upon second exposure of the same pathogen. B cells are made in the bone marrow. On each of the immune cells there are membrane-bound antibodies. These antibodies fit to a pathogen antigen like a lock in a key, these stimulates rapid generation of B cells, these then specialise to memory or effector ll cells. The T-cells are made in the thymus. T cells are different to B cells as they are unable to detect pathogens unless they are attached to an MHC complex which presents the pathogen to the T cell. Like the B cells, T cells differentiate and specialise into helper, cytotoxic or regulatory T cells. These are known as memory cells. Which means that they remember specific antigens of pathogens and have a ‘plan of action' once the body is exposed to the pathogen again.

 

 

Source: 23.2. Adaptive Immune Response – Concepts of Biology – 1st Canadian Edition (opentextbc.ca)

Nutrition is one of the key factors to keep the immune system healthy. Many vitamins and minerals play important roles in immune cell function and proliferation. Find more about nutrition and your immune system below:

Vitamin A

Vitamin A supports the normal function of the immune system and is needed to reduce inflammation as part of a healthy immune response. In addition, Vitamin A encourages the production of the primary defence mechanism, mucosa which traps pathogens. Animal studies show that vitamin A deficiency can lead to decreased efficacy of the T cell-mediated and antibody-dependent immune responses. Vitamin A can be in the form of retinol or carotenoids. Retinols are found in animal products and carotenoids can be found in plant-based sources. Each day we are recommended to consume between 600-700mcg of Vitamin A for adults. Food sources of Vitamin A in carotenoid and retinol forms include; Sweet potatoes, Carrots, Butternut squash, Peppers/capsicum, Spinach, Lettuce, Fish and seafood (tuna, mackerel and clams). Alternatively, Vitamin A can also be sourced from supplements.

B Vitamins

There are a number of B-Vitamins are required for the maintenance of the immune system including Vitamin B6, B12 and Folate (B9). Studies have shown that Vitamin B9 deficiency can lead to a reduction in T cells (CD8+) which can lead to an increased chance of infection. Whereas, Vitamin B12 is important for immune cells such as the natural killer (NK) cells, CD4 and CD8 lymphocytes. The daily requirements for Vitamin B9 are 200mcg/0.2mg and just 2.5mcg/0.0025mg of Vitamin B12. Some food sources of B-vitamins include; soy products, yeast extract, legumes, beans, green vegetables, Seafood, fish, fortified cereals, eggs and liver. Alternatively, you can gain B-vitamins from a B complex or multivitamin. Most food sources of Vitamin B12 are depleted and therefore most people are deficient in Vitamin B12, daily supplementation may be required for all.

Vitamin D

Vitamin D is the wonder-vitamin, well known for its powerful and potent benefits to bone health. Little known is its ability to support a normal function of the immune system. Vitamin D can be metabolised to 1,25-dihydroxyvitamin D [1,25(OH)2D]. A deficiency of Vitamin D has led to a deficiency of this metabolite which has been linked to increased inflammation in the body Studies have shown that people deficient in Vitamin D have higher self-reported incidences of upper respiratory tract infections. One study found a 42% decrease in the incidence of influenza after a Vitamin D dosage. Some food sources of Vitamin D include oily fish, mushrooms, fortified milk, margarine, tofu or orange juice and eggs. Alternatively, just 15 minutes of sunshine on unprotected skin is enough to absorb the necessary vitamin D. Lastly, you can purchase Vitamin D2 and D3 supplements.

Vitamin C

Vitamin C is an antioxidant that acts as a free radical scavenger to protect the immune system. Additionally, Vitamin C is thought to accumulate in the white blood cells (phagocytes) to stimulate Chemotaxis. Anecdotally, we know that sailors with scurvy had supressed immune health and were more susceptible to infections. Vitamin C is available in supplemental or food form. Food sources include berries, citrus fruits, tomatoes, kiwi, guava, broccoli, peppers, spinach and kale.

Zinc

Zinc is needed for non-specific immunity, as it helps white blood cells to become mature and function optimally. It has been confirmed that Zinc contributes to the normal function of the immune system. One study even called it the ‘gatekeeper to the immune system’. One symptom of zinc deficiency includes immune dysfunction, as well as increased oxidative stress and an extreme inflammatory immune response. Males require more daily zinc than females at 9.5mg and 7mg for females. Zinc can also be used in supplemental form. This typically is sourced from zinc picolinate, zinc citrate, zinc sulphate and zinc gluconate. I would recommend taking this alongside selenium for powerful immune support. Alternatively, food sources include seafood, beef, tofu, nuts, beans and legumes.

Selenium

Selenium helps to maintain the human immune system by creating glutathione peroxidases (GPx) of which there are 8, labelled GPx1-8. Research has shown that selenium supplementation may enhance cell-mediated immunity. Each day an adult requires between 60-75mcg for men and women. Selenium can be consumed via supplementation and is often paired with iodine. Food sources include Brazil nuts, seeds, shellfish, meat and wholegrain carbohydrates.

Copper

Copper is only need in very small amounts per day, 1.2mg. Studies have shown that copper deficiency can lead to a decreased efficiency and effectivity of the cell-mediated and humoral immune responses, as well as the number of white blood cells called neutrophils. Copper can be taken through supplement copper gluconate, copper picolinate or copper sulphate, or consumed via food. Potent source of zinc includes seafood, mushrooms, tofu, root vegetables, spinach and legumes.

The human immune system

Harriet Hunter
The human immune system

The human immune system is the body’s first barrier against potentially harmful invading pathogens - bacteria and viruses. Much like a well-oiled machine, our immune system is made up of many cogs that work together. Each supporting the role of the last. There are many factors that can affect the function of this machine we call our immune system, this includes – seasons, environment, comorbidities and nutrition.

The Human Immune System

Our immune system is governed by numerous varieties of white blood cells. These are used in the innate or adaptive immune response. The innate or non-specific immune system is made up of cells white blood cells called natural killer cells (NKs), in addition to macrophages, phagocytes, neutrophils, basophils, eosinophils and mast cells. In addition to these cells, other innate barriers for the immune system include mucous membranes, eyelashes, sweat, saliva and gastric acid. The innate response can take between 0-96 hours to work. The main process of the innate immune system is run by the white blood cell, ‘phagocyte’. This is called phagocytosis. The process begins when a ‘foreign cell’ or pathogen is detected, it then consumes and destroys the foreign cell within its own cell. In addition to the phagocytes, macrophages circulate the body and release protein-like cytokines which acts as warning signals to other cells that attach the foreign cells. Then, you have the adaptive or specific immune response. This plan of attack against invading pathogens uses T and B lymphocytes. This can take over 96 hours to take effect, or faster upon second exposure of the same pathogen. B cells are made in the bone marrow. On each of the immune cells there are membrane-bound antibodies. These antibodies fit to a pathogen antigen like a lock in a key, these stimulates rapid generation of B cells, these then specialise to memory or effector ll cells. The T-cells are made in the thymus. T cells are different to B cells as they are unable to detect pathogens unless they are attached to an MHC complex which presents the pathogen to the T cell. Like the B cells, T cells differentiate and specialise into helper, cytotoxic or regulatory T cells. These are known as memory cells. Which means that they remember specific antigens of pathogens and have a ‘plan of action' once the body is exposed to the pathogen again.

 

 

Source: 23.2. Adaptive Immune Response – Concepts of Biology – 1st Canadian Edition (opentextbc.ca)

Nutrition is one of the key factors to keep the immune system healthy. Many vitamins and minerals play important roles in immune cell function and proliferation. Find more about nutrition and your immune system below:

Vitamin A

Vitamin A supports the normal function of the immune system and is needed to reduce inflammation as part of a healthy immune response. In addition, Vitamin A encourages the production of the primary defence mechanism, mucosa which traps pathogens. Animal studies show that vitamin A deficiency can lead to decreased efficacy of the T cell-mediated and antibody-dependent immune responses. Vitamin A can be in the form of retinol or carotenoids. Retinols are found in animal products and carotenoids can be found in plant-based sources. Each day we are recommended to consume between 600-700mcg of Vitamin A for adults. Food sources of Vitamin A in carotenoid and retinol forms include; Sweet potatoes, Carrots, Butternut squash, Peppers/capsicum, Spinach, Lettuce, Fish and seafood (tuna, mackerel and clams). Alternatively, Vitamin A can also be sourced from supplements.

B Vitamins

There are a number of B-Vitamins are required for the maintenance of the immune system including Vitamin B6, B12 and Folate (B9). Studies have shown that Vitamin B9 deficiency can lead to a reduction in T cells (CD8+) which can lead to an increased chance of infection. Whereas, Vitamin B12 is important for immune cells such as the natural killer (NK) cells, CD4 and CD8 lymphocytes. The daily requirements for Vitamin B9 are 200mcg/0.2mg and just 2.5mcg/0.0025mg of Vitamin B12. Some food sources of B-vitamins include; soy products, yeast extract, legumes, beans, green vegetables, Seafood, fish, fortified cereals, eggs and liver. Alternatively, you can gain B-vitamins from a B complex or multivitamin. Most food sources of Vitamin B12 are depleted and therefore most people are deficient in Vitamin B12, daily supplementation may be required for all.

Vitamin D

Vitamin D is the wonder-vitamin, well known for its powerful and potent benefits to bone health. Little known is its ability to support a normal function of the immune system. Vitamin D can be metabolised to 1,25-dihydroxyvitamin D [1,25(OH)2D]. A deficiency of Vitamin D has led to a deficiency of this metabolite which has been linked to increased inflammation in the body Studies have shown that people deficient in Vitamin D have higher self-reported incidences of upper respiratory tract infections. One study found a 42% decrease in the incidence of influenza after a Vitamin D dosage. Some food sources of Vitamin D include oily fish, mushrooms, fortified milk, margarine, tofu or orange juice and eggs. Alternatively, just 15 minutes of sunshine on unprotected skin is enough to absorb the necessary vitamin D. Lastly, you can purchase Vitamin D2 and D3 supplements.

Vitamin C

Vitamin C is an antioxidant that acts as a free radical scavenger to protect the immune system. Additionally, Vitamin C is thought to accumulate in the white blood cells (phagocytes) to stimulate Chemotaxis. Anecdotally, we know that sailors with scurvy had supressed immune health and were more susceptible to infections. Vitamin C is available in supplemental or food form. Food sources include berries, citrus fruits, tomatoes, kiwi, guava, broccoli, peppers, spinach and kale.

Zinc

Zinc is needed for non-specific immunity, as it helps white blood cells to become mature and function optimally. It has been confirmed that Zinc contributes to the normal function of the immune system. One study even called it the ‘gatekeeper to the immune system’. One symptom of zinc deficiency includes immune dysfunction, as well as increased oxidative stress and an extreme inflammatory immune response. Males require more daily zinc than females at 9.5mg and 7mg for females. Zinc can also be used in supplemental form. This typically is sourced from zinc picolinate, zinc citrate, zinc sulphate and zinc gluconate. I would recommend taking this alongside selenium for powerful immune support. Alternatively, food sources include seafood, beef, tofu, nuts, beans and legumes.

Selenium

Selenium helps to maintain the human immune system by creating glutathione peroxidases (GPx) of which there are 8, labelled GPx1-8. Research has shown that selenium supplementation may enhance cell-mediated immunity. Each day an adult requires between 60-75mcg for men and women. Selenium can be consumed via supplementation and is often paired with iodine. Food sources include Brazil nuts, seeds, shellfish, meat and wholegrain carbohydrates.

Copper

Copper is only need in very small amounts per day, 1.2mg. Studies have shown that copper deficiency can lead to a decreased efficiency and effectivity of the cell-mediated and humoral immune responses, as well as the number of white blood cells called neutrophils. Copper can be taken through supplement copper gluconate, copper picolinate or copper sulphate, or consumed via food. Potent source of zinc includes seafood, mushrooms, tofu, root vegetables, spinach and legumes.

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