The immune system is a complex defence network made up of three layers (Figure 1) – physical, chemical and mechanical. The first level of defence represents the physical or mechanical barriers which includes the skin, mucous membranes and cilia (which trap and prevent pathogen entry as found in respiratory and digestive tracts). Chemical barriers include pH (as in the stomach but also in tissues), fatty acids and other microcidal molecules while temperature (fever) represents a physiological response.
Figure 1: The three main layers of the immune system
Pathogens (bacteria, viruses, mould, fungi or other microbes) then face the second layer of the immune system. Knows as our “innate” system it has the ability to respond rapidly to infection and consists of a variety of white blood cells. These specialised cells either engulf, neutralise or bind to foreign cells triggering an adaptive immune response.
The third level of defence is acquired, and is the most sophisticated and delayed but gives the body its immunological memory over time.
Multi-Dimensional Influences on our Immune Health
While the above comprise a comprehensive defence against pathogens, it is our overall health that dictates their capacity to function optimally.
There are key drivers that holistically combine to support a robust and healthy immune response:
Immune nutrition: while individual nutrients have been linked to supporting various areas of immune health, they should always be considered as part of a varied whole-food diet and only supplemented when your levels are low when tested (blood pathology or other functional assessment). The nutrients most commonly associated with healthy immune responses include the B-group vitamins, Vitamin A for mucous membranes, zinc and iron. Vitamin D has been shown to support production of anti-microbial molecules and also reduce respiratory tract infections.
Digestive health: the gastrointestinal system plays a central role in immune balance. This is testified by the gut-associated lymphoid tissue (GALT) surrounding the digestive tract, which represents 70% of the entire immune system. If the intestinal barrier becomes compromised and damaged (as in gut permeability or ‘leaky gut‘) inflammation ensues. This hyperpermeability allows pathogens and other toxins to enter the body triggering further inflammation and increasing the risk of allergies, autoimmunity and frequent or recurring infection.
Nervous system: psychological stressors activate the sympathetic nervous system. Chronic stress has been associated with suppressing multi levels of our immune response while exacerbating pathological immune responses. Repeated exposure to recent and chronic stressful life events has been shown to increase an individual’s risk of developing an infectious illness (e.g. common cold). Both acute and chronic stressors equate to increases in the circulation of inflammatory markers.
Acidity: the pH of the extracellular environment has a direct influence on a broad range of immunological functions. For example, an acidic ‘terrain’ can trigger low grade chronic inflammation. When stomach pH is too high, its effectiveness against pathogens is compromised but so too is digestive capacity, resulting in inflammation or damage to the gastrointestinal tract.
Strong foundations to immune and overall health always lie in individualised assessment and support by fully trained qualified professionals.