The immune system is the body’s defence system. It protects us against pathogens which are micro-organisms like viruses, bacteria, protozoa, and fungi, that can cause disease. The immune system fights off these disease-causing microbes, keeping them in balance with the health-promoting microbes of our microbiota (the ‘friendly’ bacteria, yeasts, and fungi occurring throughout the body that are beneficial to health).

Because pathogens rapidly mutate and evolve, our defence system needs to be responsive and have multiple defences. The first line of defence is the innate response. This response is non-specific meaning that it will not discriminate against specific bacteria, viruses, or parasites. Inflammation is one of the key innate responses. People think of inflammation as ‘bad’ or undesirable but when you the cardinal signs of inflammation: redness, swelling, warmth, along with pain, there is a complex interplay of cells and molecules working to prevent pathogens from causing damage and clearing out waste products of the healing process. Conversely, the adaptive response adapts to specific pathogen threats, allowing us to better defend ourselves against future infection. It includes a range of different cells and systems that identify specific patterns on the surface of pathogens and builds a large, targeted response specifically against them. Therefore for many illnesses, exposure when young, or vaccination, will provide lifelong, or long-term immunity to the illness.

Disorders of the immune system can result in autoimmune diseases, inflammatory diseases and cancer. Immunodeficiency occurs when the immune system is less active than normal, resulting in recurring and life-threatening infections. In humans, immunodeficiency can either be the result of a genetic disease such as severe combined immunodeficiency, or acquired conditions such as HIV/AIDS, or the use of immunosuppressive medication.

Autoimmunity results from a dysfunction of the immune system in which self-cells (or non-pathogenic microbes residing on tissue) are targeted by the immune system and result in damage to our tissue.

What is it made up of?

The immune system includes cells that help to recognise pathogens and differentiate them from ‘self’ tissue and beneficial microbes, along with proteins that help to regulate the inflammatory response (inflammasomes). It also includes many of the more commonly known immune components; white blood cells (leukocytes) that engulf and destroy pathogens, along with lymphocyte B and T-cells which identify, mark, and target pathogens and cells infected with pathogens for destruction. The various components of the inflammatory systems work to help encourage healing by encouraging increased blood flow to areas of infection (transports immune cells to the area), swelling and pain (which results from the increased flow and slow clearance, but also helps immobilise the area to prevent further damage).

Signs your immune system is not as healthy as it should be:

• Frequent or persistent colds or flu-like viruses
• Severe hay-fever or other allergies
• Autoimmune conditions

Note: Many serious conditions can result in these signs and symptoms. If you are experiencing any of these, consult with your doctor for proper diagnosis and treatment.

Nutrients for a healthy immune system

The foundation for a healthy immune system is a good diet that provides sufficient energy, essential fats, protein, and micronutrients.

Conversely, diets that are high in processed and refined foods, and especially those high in trans-fats and sugar are likely to worsen responses to infections.

Also, many nutrients have been shown to help support immunity, such as:

• Omega 3 fats help us to regulate immunity and inflammation in conjunction with the ‘pro-inflammatory’ omega 6 fats. Omega 3 fats are found in fatty fish and vegan sources like flaxseeds and algae.
• Vitamin A is intricately involved in immunity, ¹ and sufficient Vitamin A is associated with immunity to illness and infections.^{2, 3}
• Vitamin C, contrary to popular belief, probably won’t cure the common cold but research suggests that it might help to reduce symptoms of colds and shorten their duration,⁴ and might even help to prevent the occurrence of colds in athletes and others prone to higher levels of stress when taken regularly.^{5, 6}
• Vitamin E also has immunomodulatory effects.⁷
• Vitamin D is a key immune regulator and has also shown promise for aiding several auto-immune conditions like systemic lupus and rheumatoid arthritis.⁸
• Zinc is also a key co-factor for immune responses. Evidence suggests that zinc supplementation might help reduce the duration and severity of the common cold.^{9, 10}

• Research shows that bioflavonoids from plants reduce upper-respiratory-tract infections.¹¹ Other antioxidant-rich foods like grapeseed,  rosehips, and cacao improve antioxidant status and immunity and reduce inflammation.^12-17
• Adaptogens are herbs that are stress ‘tonics’ that help us to respond to stressors more effectively. Among the adaptogens, ginger, ginseng, gotu kola, ashwagandha and astragalus have demonstrated a range of antioxidant, anti-inflammatory and immune-boosting properties.^18-26
• Common herbs like rosemary are anti-inflammatory and anti-microbial and may benefit immune status.²⁷
• Spices such as turmeric are likely to improve immune function.²⁸
• Many mushrooms help to provide immunity against infections. For example, shiitake mushroom is thought to aid immunity by increasing white blood cell activation.^{29, 30}
• Probiotic supplementation reduces the incidence and severity of respiratory infections, ^31-36 and probiotics are suggested for use to reduce inflammation and infection following several types of surgeries.^37-40
• Spirulina might reduce the effects of seasonal allergies, along with reducing oxidation and inflammation.^41-43
• Chlorella has demonstrated the capacity to provide a short-term ‘boost’ to immunity by increasing levels of natural killer cells.⁴⁴

NOTE: It must be remembered that typically, these nutrients (especially the essential vitamins and minerals) work to support immunity by supporting the diet. In other words, many people don’t eat enough pre-formed vitamin A and zinc, and these are integral to the modulation of immune function. Therefore, the use of these is to restore us to sufficiency and there may be no benefits from mega-dosing (which may worsen outcomes…)

Treat all claims of ‘cures’ and ‘preventatives’ with caution, especially in the current climate of emerging threats like novel flu viruses and other similar viruses like the current COVID-19 novel coronavirus pandemic.

Treat all claims of ‘cures’ and ‘preventatives’ with caution

Lifestyle and immunity

Exercise

Exercise is known to improve health overall, and specifically the functions of the immune system. However, excessive amounts of exercise, leading to over-stress and overtraining, can result in impaired immune function and greater risk of infections, especially colds and flu-like viruses.⁴⁵

Excessive exercise may result in a greater risk of infections

Stress

Stress, in particular work-related stress, is known to impact the immune system and reduce resistance to infections.⁴⁶ Interestingly, the effort-to-reward ratio (how much we value the benefits from our job versus the effort it requires) has a greater effect on immunity than overwork.⁴⁷

How much we value the benefits from our job versus the effort it requires has a greater effect on immunity than overwork

Other factors that can affect immunity:

• Poor sleep
• Smoking
• Excessive alcohol use

How to Support Immunity

Eat 6 servings of vegetables per day

Vegetables help to provide many essential and non-essential, yet health-promoting nutrients…and most of us don’t eat enough of them.

Make sure you are eating enough, and enough protein

Being consistently ‘under-fuelled’ is a sure-fire way to put yourself at risk of colds and flu-like infections. Make sure that you are eating enough and always base your meals on a serve of a quality protein food. Amino acids like glutamine from protein are also associated with reducing infection rates in athletes.

Consider supplementing with a good-quality multi-nutrient

The key consideration for immunity is not to get massive doses of particular nutrients to ‘boost’ immune function, but instead to make sure you have all the nutrients your immune system needs to function correctly. A quality multi-nutrient can help you to fill in the gaps in your nutrition and supply some of the nutrients you may not always take in each day.

Exercise, but not too much

If you’re new to exercise, start at a level you can do relatively easy and build from there. Work up to taking at least 7,500 steps per day and doing 2 sessions of weight-training or resistance work (like bodyweight workouts or progressive yoga if you don’t want to hit the gym). Add on extra cardio if you can.

Get 8 hours of sleep per night

Sleep is critical to health. Try to get to bed a little bit earlier if you’re not getting at least 7 hours of quality sleep per night. Also, try shutting off your phone and other devices around 2 hours before bedtime.

Reduce your life and work stress

Stress can impact immune function. If you have stressful relationships or environments (like work) try to change them to more fulfilling ones if able.

Meditation is also a great way to reduce the impacts of life’s stresses on how we think and feel. As with exercise, start with just a little (even as little as 1 minute of meditation on day one!) and build over time until you are doing around 20min or more per day.

Conclusion

A healthy, well-functioning immune system is a function of having a healthy, well-balanced life! There are no pills or potions that will magically ‘boost’ your immune system, but you can help to support the best functioning immune system you can have by following some simple guidelines of good food, movement, intelligent supplementation, and mindfulness.

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