The immune system
Your immune system is a large network of organs, white blood cells, and proteins. The lymphatic system connects all the organs together and transports the immune cells, so they can all work together to protect you from pathogens. The immune system is divided into two parts; the innate immune system and the adaptive immune system.
The innate immune system, also known as general resistance, consists of several defensive mechanisms that are constantly active and serve as the first line of defence against infections. These responses are not limited to a single bacteria or virus. The innate immune cells target molecular patterns that are seen on all microorganisms.
Adaptive immunity, also known as the acquired immune system, contains specialized immune cells and antibodies that target and eliminate foreign invaders while also remembering what those substances look like and creating a new immune response to prevent sickness in the future. Humoral immunity and cell-mediated immunity are the two parts of the adaptive immune responses that allow the human body to protect itself against bacteria, viruses, and toxins in a targeted manner.
Humoral immunity is an antibody-mediated response that occurs when foreign material (antigens) are detected in the body. This foreign material typically includes invaders such as viruses or bacteria. This mechanism is primarily driven by B cell lymphocytes, a type of immune cell that produces antibodies after the detection of a specific antigen.
Cell-mediated immunity does not depend on antibodies for its adaptive immune functions. Cell-mediated immunity is primarily driven by mature T cells, macrophages, and the release of cytokines in response to an antigen. Cytokines are small protein-based cell signalling molecules that aid cell-to-cell communication in immune responses and stimulate the movement of immune cells towards sites of inflammation, infection, and trauma.
Cold and flu — What’s the difference?
It is hard to tell whether you have a cold or the flu since they have many of the same symptoms and both are widespread during the colder months. The difference is that the flu is caused by the influenza virus, while colds are caused by many different types of viruses. Rhinoviruses cause up to 50% of common colds. There are more than 100 different rhinoviruses. The symptoms of the flu can include fever, chills, cough, sore throat, runny nose, body aches, headaches, and fatigue. Cold symptoms are usually milder than flu symptoms and congestion is more common.
Immune System & Gut Health
The gastrointestinal tract plays a key role in immune function. The gut contains about 70% of the body’s immune cells and there’s a complex interaction between the intestinal microbiota, the intestinal epithelial layer, and the local mucosal immune system. This is why prebiotic and probiotic foods are important to support the immune system. Making sure you get enough fibre in your diet is a good way to keep your microbiome happy and including extra prebiotics in the diet is a plus. Some good prebiotic foods are: bananas, barley, leeks, garlic, Jerusalem artichoke, legumes, apples, oats, onions, rye, dandelion greens, and asparagus.
Garlic is an especially good one since studies point to the fact that garlic can help reduces cholesterol, inhibits platelet aggregation, reduces blood pressure, and increases antioxidant status. Garlic, onion, and shallots also contain antimicrobial compounds that differ in strength with their method of preparation. Fresh garlic is the strongest and most of it’s antimicrobial properties are lost after 5 minutes of cooking whereas shallots maintain their potency when cooked.
There is new research on the positive effects of probiotics as preventative and complementary treatment in patients with respiratory tract infections. They may help to reduce the severity of symptoms, reduce the duration of disease, and improve quality of life.
Nutrients that Strengthen the Immune System
Vitamin C
Vitamin C acts as a regulator of the activation and continued survival of immune cells. It has been shown to significantly enhance immune cell number and function, which suggests it has benefits for supporting adaptive immunity and prevention of illness. It stimulates immune cells migration to the site of infection and enhances microbial killing. Vitamin C has demonstrated the ability to increase Nitric oxide (NO) production. NO production by epithelial cells is part of the antiviral response.
Vitamin D
The first hint of how important Vitamin D’s role on the immune system was made by the discovery of the presence of the vitamin D receptor on almost all cells of the immune system. Vitamin D can modulate both the innate and adaptive immune responses. Deficiency in vitamin D is associated with increased autoimmunity (where immune cells attack our own body) as well as an increased susceptibility to infection.
Zinc
Zinc plays a central role in the immune system, and a person who is zinc-deficient can experience increased susceptibility to a variety of pathogens. Zinc is involved in the function of many immune cells. Zinc plays a role in basic cellular functions such as DNA replication, RNA transcription, cell division, and cell activation. Zinc also functions as an antioxidant and can stabilize membranes which is important when there is any inflammation or trauma.
Foods that Weaken the Immune System - Sugar
Studies have found that high levels of glucose may lead to impaired immune system function and other pathological conditions. It has been shown that excessive intake of dietary sugars can cause metabolic disorders and increase inflammatory mediators which leads to insulin resistance (prediabetes) and low-grade chronic inflammation. Research has also shown that the gut microbiome is affected by dietary sugars and this causes increased inflammation by reducing the diversity and functional activity of the beneficial gut flora.
Important Factors for Immune Health
Sleep
Sleep and the circadian system have a strong regulatory influence on immune functions. One example is sleep on the night after experimental vaccinations against hepatitis A produced an increased number of T-cells and antibodies, which indicates that sleep is important in the formation of immunological memory. Other studies have shown that individuals who chronically get less than seven hours of sleep a night are three times as likely to develop the common cold. Adults should be getting at least 8 hours of sleep a night.
Exercise
Research shows a clear relationship between moderate exercise and illness prevention. We now see exercise as an important way to support the immune system by stimulating the ongoing exchange of white blood cells between the circulation and tissues in the body. Metabolically, moderate exercise promotes direct anti-inflammatory effects, and improves glucose and lipid metabolism over time.
Exercising at a moderate to vigorous intensity for 15-60 minutes is optimal for the immune-boosting benefits. Doing this regularly, ideally every day, will promote the immune and metabolic systems to continuously strengthen. On the other hand, prolonged high intensity training can suppress your immune system since this can put more stress on the body.
Stress Reduction
Studies have shown a link between life stress and higher likelihood of infectious and inflammatory diseases, but only recently has the mechanism behind this connection become clearer. This link is due to the effect by hormones of the hypothalamus-pituitary-adrenal (HPA) axis. Chronic activation of these stress responses results in chronic production of glucocorticoid hormones (e.g. cortisol) and catecholamines (e.g. epinephrine) from the HPA axis. Prolonged psychological stress results and chronic exposure to these hormones may predispose a person to lowered immunity and repeated infection. These hormones are immune suppressing and even the transient cortisol spike after intensive exertion can increase susceptibility to infection.
Forest Bathing
Along with its ability to reduce stress, forest therapy has been shown to improve immune function. Studies have reported that volatile substances (phytoncides) extracted from trees have a positive effect on immune function, supporting the idea that a forest’s environmental factors play an instrumental role in improving immune function. One study indicated that these substances can increase the activation of natural killer (NK) cells and intracellular anti-cancer molecules. This is supported by several studies in animals and humans, suggesting that fragrances from trees can reverse stress-induced immunosuppression, and normalize immune function and neuroendocrine hormone levels.
Stress stimulates sympathetic nervous system and HPA axis activity to increase cortisol secretion. Phytoncides have positive effects on autonomic nervous system, stress reduction, cortisol level reduction, blood pressure reduction, immune system enhancement, and chronic fatigue. It has also been reported that inhalation of phytoncide through breathing during forest bathing can enhance the cytotoxic activity of NK cells. Furthermore, NK cells are increased by the decreased production of stress hormones.
Herbs for Immune Health
The herbalist Christopher Hobbs identifies 3 levels of herbal immune activity which are described below:
Deep Immune Tonics or Immune Modulators
These are used when there is a chronic problem or when the immune system needs to be tonified and strengthened. They help to stimulate T- and B- cells, macrophages, and natural killer cells into action, but also stimulate Suppressor T cells that keep the immune system from becoming over-active. This is likely the reason that some of them have been used as a complementary treatment for malignancies as they help in “modulating” the cells involved in our immunological defences. Some herbal examples include: Astragalus, Reishi, Shiitake, Turkey tail, and Schizandra.
Surface Immune Activation or Antimicrobials
These are used in an acute infection and will act directly on the bacteria or virus, while also stimulating the function of the immune system as a whole. Some herbal examples include: Garlic, Echinacea, Usnea, and Sambucus (elderberry).
Adaptogenic Action or Hormonal Modulation
These herbs work through hormonal modulation of the immune response i.e. they help regulate the effects that stress and increased cortisol have on the immune system. Herbal examples include: Siberian and Korean Ginseng, Licorice, Rhodiola, and Ashwagandha.
In Summary
Often it’s the most basic elements of lifestyle that are the most effective in treatment and prevention of infection:
· Adequate water intake
· Outside time: Fresh air / Forest bathing / Exposure to sunshine (get Vitamin D)
· Regular exercise
· Eating a balanced diet
· Adequate sleep: aim to get at least 8 hours
· Stress reduction
o Relaxation time during waking hours i.e. cortisol reduction
o Gratitude practices help to maintain a positive state of mind
** Medical disclaimer: Please do not try any of the supplements or remedies suggested in this post without consulting your Naturopathic or Medical Doctor
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