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Immune System

What Is The Immune System?

The immune system is a complex biological system, consisting of many different types of cells, tissues and organs, each with their own specific function. The immune system’s major functions are to recognise and neutralize harmful substances and infective organisms (like bacteria, viruses and parasites), heal damaged tissue and remove cells of our own body that are not functioning correctly, such as cancer cells. The immune system gets stronger as we approach adulthood, but again gets weaker in old age. This is why children and the elderly are more susceptible to illness.

The most important ability of the immune system is to be able to distinguish between self and non-self, or in other words, normal and abnormal. If it is not able to do this properly, it will either allow infectious organisms to invade, or begin attacking your own body. The latter is known as autoimmune disease. Early on, the body learns to recognise specific proteins that are on the surface of the body’s cells as ‘self’. As we are exposed to infectious organisms, the body learns to recognise proteins on the surface of the invaders cells, known as antigens, which signal that it should attack them.

What Are The Different Types Of Immunity?

There are three types of immunity in humans called innateadaptive, and passive immunity.

What Is Innate Immunity?

Innate immunity consists of the parts of the immune system that you are born with and that do not change significantly throughout life. It includes defensive structures such as the skin and mucous membranes, as well as a number of white blood cell types such as Natural Killer Cells. These are general defences, which means that they don’t recognise specific invaders, but rather that you have been infected and attempt to attack all invaders in a similar way. The innate immune system is your body’s first line of defence against new threats. While it can often deal with infections before they become an issue, invaders are sometimes able to overcome it. This is where adaptive immunity comes in.

What Is Adaptive Immunity?

Adaptive, or acquired, immunity is the part of the immune system that changes over time, learning to recognise new invaders and mount a response to them. This is known as immunological memory.

This memory is why vaccines can confer immunity, as well as why we do not get certain diseases (like chickenpox) twice. This is also the part of the immune system which takes the most time to develop. In children, the adaptive immune system is largely untrained, which is why they get sick so much more often. By adulthood, we have come into contact with many more pathogens and therefore are able to stay healthier longer.

The adaptive immune system relies on two special types of white blood cell, called lymphocytes. These are B-cells and T-cells. B-cells do not directly attack invaders, but are more involved in remembering what they look like and ensuring T-cells (which do attack invaders) and other immune cells can recognise them. One way they do this is through production of antibodies. Antibodies are protein molecules which circulate through the body and bind to the surfaces of invading organisms. Through binding they coat the invader (making it harder for it to move around or get inside cells) and signal to T-cells to attack.

What Is Passive Immunity?

Passive immunity is the passing of resistance to a disease from one person to another. An important role of passive immunity is to protect new-born infants from infection. Various antibodies are transferred from mother to child in the womb and through breast milk. The infant therefore temporarily receives the mother’s highly developed immunity while its own immune system begins to develop.

Passive immunity is short-lived (from days to several months), and the immunity to a wide range of organisms that an infant has while breast feeding is gradually lost as it is weaned. Toddlers and older children will therefore not be resistant to the complete range of organisms their parents are. As such, focus on supporting their growing immune system is paramount to prevent illness and develop their adaptive immune system.

What Happens To The Immune System As I Age?

As with many other biological functions, the immune system becomes less effective as you age. This includes its ability to recognise and ward off pathogens, prevent the proliferation of cells of our own body that cause disease, as well as its ability to recognise self from non-self. As we age, we therefore become more likely to develop a number of diseases, including autoimmune disorders, and become more susceptible to invading organisms.

It is therefore important to focus on immune health as you age. Some micronutrient deficiencies are also more prevalent in the elderly, and these have been linked to a decline in the immune system.

How Can You Strengthen Your Immune System?

The immune system is complex, relying on the correct function of a wide variety of cells, tissues and organs. Optimal immune function therefore relies on maintaining a healthy lifestyle.

This includes following a helathy, well-balanced diet, getting an adequate amount of sleep, regular exercise, reducing stress, and avoiding toxic substances.

Deficiencies in zinc, selenium, iron, copper, folic acid and vitamins A, B6, C, D and E have been associated with poor immunity and higher rates of disease. Ensuring you are receiving optimal amounts of these nutrients is therefore essential. These nutrients can be obtained from a healthy diet, centred on plant-based foods, as well as supplements designed to optimise your immunity. Contact the MNI dietician at for healthy diet tips for you and your children.

ImmunoVance has been specifically formulated to contain all of the micronutrients essential to immune function. These, together will scientifically prove herbal extracts, work to strengthen your immune system and optimise its function. Read more about ImmunoVance here.

What Negatively Affects Immunity?

The health of your immune system is inseparable from general health. Factors which negatively affect general health, therefore, impair the functioning of the immune system. These include poor diet, stress, lack of exercise and bad habits such as smoking and excessive alcohol consumption.

Stress may seem to be the least obvious, and yet it is a major contributor to general negative health, and specifically affects the immune system. In the short term, stress can have a positive effect on immunity, priming the body for attack. Short term stress is therefore beneficial, or at least not harmful. Stress becomes an issue, both for health and immunity, when it is chronic.

Biologically, stress causes a number of changes in the body. Many of these are linked to the secretion of cortisol, a hormone which regulates a variety of processes in the body. Cortisol prepares you for ‘fight or flight’, steering energy away from processes that normally use energy but would not necessarily be useful to helping you survive an attack by a bear, for example. One of the biological functions which these hormones impair is the immune response. In the short term, this is not problematic, but in the long term, if cortisol is secreted in excess, the body can enter a state of chronic immune deficiency. Managing stress is therefore extremely important to ensuring optimal immune function.

Why Does Exercise Supress The Immune System?

Regular exercise is important to maintaining health and the immune system. Despite this, excessive amounts of exercise can negatively affect immunity. This is because exercise is a form of stress. During a normal exercise regime, the body has time to recover and return to normal. When exercise is prolonged (over 90 minutes) and extreme, however, the body does not get this opportunity, and it begins to affect the immune system in a similar way to chronic psychological stress. Athletes may also develop deficiencies of certain micronutrients important to the immune system, such as zinc, which is lost through sweat.

The phenomenon is especially observed in endurance and professional athletes, who are more likely to develop upper respiratory tract infections than the general population. Prolonged, intense exercise leads to suppression of the immune system, affecting white blood cell function, lasting up to 24 hours. During this period, athletes are more susceptible to infection. If adequate rest is not taken between sessions, the body is not able to normalise, and a chronic state of immune suppression can develop.

Adequate recovery periods and rest is therefore important, as is focus on good nutrition, high in vitamins and minerals.  It has also been found that maintaining energy levels through consumption of carbohydrates while training can reduce the negative effect on the immune system.

Infectious organisms

What Is An Infection?

An infection occurs when a foreign organism (such as a bacteria or virus) colonises, gets nourishment from and reproduces inside the body. Infection does not necessarily lead to disease, but when the organism damages cells and tissue, it does.

Among the millions of types of organisms, only a few are able to infect our bodies and even fewer are able to cause disease. Those which do are called pathogens. Pathogens usually enter the body through openings to the environment such as the nose, mouth, eyes and wounds. They then migrate to tissues which they can more easily live in.

Infections can be divided into primary and secondary infections. Primary infections are caused by the first organism to invade the body. Secondary infections are caused by organisms that colonise the body due to a weakened immune response or other complications caused by a primary infection. For example, flu, a primary infection, can cause infection of the lungs or airways by bacteria, leading to bronchitis or pneumonia.

What Is A Virus?

A virus is the smallest and most primitive type of infectious organism. There are thought to be millions of types of viruses, found almost everywhere on earth. These can infect anything from the smallest bacteria to mammals, reptiles and plants.

Viruses cannot reproduce and survive on their own in the way a bacteria, plant or animal can. Instead, they consist of only a few genes packaged tightly into an outer coating made of protein. The coat serves to protect the viral DNA and help the virus to break into and enter a host cell. Once inside, their genes take over the replication machinery of the cell, causing it to produce more viruses. In the process, the cell dies, either because it cannot sustain both itself and the virus, or because the virus causes it to swell until it bursts. New viruses are then released, which spread into the environment and infect other cells.

What Is A Bacteria?

Bacteria are microscopic, single-celled organisms which are able to replicate and survive on their own. After viruses, they can be considered the next simplest infective agent. Bacteria can be found in almost every environment on earth, from the soil to the bottom of the ocean, on and in plants and animals, and even in radioactive waste and the atmosphere.

Most bacteria are essential to life on earth. They are extremely important to cycling nutrients, from causing the decomposition of dead animals and plants, to creating new nutrients by turning nitrogen in the air into fertilizer that plants can use. It is thought that bacteria where the first organisms to begin producing oxygen millions of years ago, thereby creating a world that was hospitable to other, more advanced life.

Surprisingly, the majority of bacteria living in your gut and other parts of your body are actually good for you. They keep other dangerous bacteria at bay by outcompeting them, or even producing their own antibiotics to kill their competition. These bacteria also help regulate your immune system, improve your overall health and produce nutrients which you may not usually be able to acquire from your diet. This is one reason why bacteria are used to create foods such as yogurt and other fermented foods.

Less than 1% of bacteria can actually be considered dangerous. The few types of bacteria that can make you sick cause diseases such as pneumonia, cholera, tuberculosis and food poisoning, amongst others. They cause disease by invading tissue and releasing toxins which damage cells and organs.

Are There Other Infectious Organisms?

Yes, there are a few. Fungi, protozoa and parasitic worms are more complex than viruses and bacteria. Infection by these organisms is not as common, however, and is often linked to unhygienic environments, contaminated foods and insects.

Fungal infections most often affect the skin and nails and sometimes the airways. They do not usually cause severe disease, but in some cases can, especially when infecting the lungs. Fungi are responsible for common conditions such as athlete’s foot and ringworm.

Protozoa are usually contracted from contaminated water or bites from insects like mosquitos. These organisms cause diseases like malaria and amoebic dysentery.

Parasitic worms are internal parasites and can be contracted from soil, water, raw meat and infected surfaces. Proper sanitation, cooking food thoroughly and avoiding swimming in stagnant water can efficiently prevent them.

What Do Antibiotics Treat?

Antibiotics specifically treat bacterial infections and have no effect on viruses. Taking an antibiotic for the flu is therefore unnecessary and will have no effect, unless your doctor has reason to believe that a secondary bacterial infection is developing. This can be difficult for a doctor to determine, and so they may prefer to be cautious and prescribe antibiotics just in case.

Over prescription and incorrect use of antibiotics can give rise to bacteria that are resistant to these drugs. It is therefore extremely important to take antibiotics exactly as they are prescribed.

Unlike antibiotics, which can kill a broad spectrum of bacteria, antivirals, prescribed for certain viral infections, are often very specific to the virus they target. This is why antiretroviral medication can not be used for the flu, for example. Because of this specificity, many viral infections cannot be directly treated.

What Makes Us Sick?

Why Do We Get Sick?

We get sick due to an infection by a foreign, disease causing organism. The most common symptoms of sickness, such as a runny nose, cough, fever and fatigue are, however, not caused directly by the infecting organism, but are rather part of your body’s immune response. For example, a runny nose results from your body trying to flush an infection out with increased mucous production.

Microorganisms can cause disease in many ways, invcluding by releasing toxic substances, invading cells and tissues as well as releasing signalling molecules that can affect the whole body. These are the effects that damage the body, and are why it is essential to ensure the infection lasts for as short a time as possible, and specific treatment for the infection, rather than its symptoms, receive focus.

Why Are We More Likely To Get Sick In Winter?

Scientists are still unsure why we tend to catch colds and flu mainly in the winter. There are, however, a number of hypotheses, and as with most things in biology, the answer is more likely to be a complex interaction of all of them, rather than any specific one in particular.

It is thought that cold, dry air protects viruses and bacteria, allowing them to survive in the environment longer. The same conditions may also dry out the organisms, making them lighter and able to travel further. Cold, dry air also prevents mucous secreted in the nose, etc., from being as effective at clearing out inhaled material, giving the organisms more time to gain a foot hold. Another reason is that people spend more time indoors in winter, creating a perfect environment for pathogens to spread from one person to the next.

When Should I Go To The Doctor For A Cold Or The Flu?

Colds and flu will usually clear up on their own but, in some cases, they may become more severe or result in secondary infections. If you are unsure whether to go to the doctor or not, it is always better to be cautious – rather pay a visit to your doctor than wait until an illness becomes really problematic. This is especially important for individuals who are at greater risk of developing serious complications, including young children, the elderly, immunocompromised individuals, pregnant women and persons suffering from respiratory conditions, such as asthma.

If you are an otherwise healthy individual, and experience any of the following symptoms, you should contact your healthcare practitioner:

  • You are not recovering, your symptoms are not subsiding, or are getting worse
  • Unrelenting fever: If the fever does not subside after a few days or respond to over the counter medication
  • Persistent vomiting or diarrhoea
  • Shortness of breath
  • Worsening or persistent cough

See your doctor immediately or visit the emergency room of you experience any of the following:

  • Chest pain
  • Severe weakness
  • Difficulty breathing or breathlessness
  • Severe headache
  • Severe rash


What Is A Vaccine?

A vaccine is a medicine aimed at preventing a disease rather than curing it. In medical terms, this is known as a prophylactic treatment. Vaccines train your immune system to recognise certain infectious organisms without actually having to come into contact with them. In order to do this, they contain only the parts of the organism that your immune system can recognise, killed organisms, or a similar organism that doesn’t cause disease. Therefore, a vaccine doesn’t make you sick, but your immune system can recognise the important antigens and train itself to recognise them in future.

Over time, vaccines have reduced the number of infections (and deaths) linked to many infections. For example, vaccines have eliminated smallpox. Getting vaccinated therefore not only protects you, but those around you, especially children and the elderly, as you are less likely to carry and spread an infectious organism if it is eliminated or supressed as soon as it tries to invade your body.

If My Body Can Recognise Previous Infections, Why Do I Get The Flu & Need A Flu Vaccine Every Year?

The flu virus has developed to change itself rapidly in order to avoid detection by our immune system. The strain that infected you last year is therefore very unlikely to be the same one that infects you this year. Before each flu season, scientists and regulators meet to decide which types of the virus will be more prevalent that season. Pharmaceutical companies then begin production of a vaccine containing antigens for these particular strains. By the next season, however, the virus has again changed, and so a new vaccine needs to be developed.

There is also not just one type of flu circulating at any one time, but thousands of slightly or very different versions. Some of these may be similar to what has been vaccinated against or what has been experienced before, and so the body can recognise and fight them off quicker, leading to less severe and shorter duration of symptoms.

Therefore a vaccine can never provide complete protection. In general, however, your chance of catching the flu is reduced by half, and the likelihood you get very sick is much less.

ImmunoVance contains micronutrients essential to optimal immune function. It has been specifically formulated to deliver those vitamins and minerals that are difficult to obtain through our modern lifestyles, and which are often more seriously depleted in the elderly. ImmunoVance® may therefore aid in preventing the decline of your immune system as you age.

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