Extrinsic asthma occurs when an allergen provokes an immunoglobulin (Ig) immune response. The allergen passes through the epithelial barrier and comes into connection with the dendritic cell. It is here where the dendritic cell presents the antigen to the T lymphocytes (T cell), which then becomes an allergen-specific helper T cell. Helper T cells produce cytokines that are essential for the stimulation of B cells, B cells construct antibodies (Doeing & Solway, 2013). Antibodies attach themselves to basophils and mast cells, which can be located in the smooth muscle of the respiratory system. Here they continue to circulate throughout the body until the same type of antigen causes another immune response. These circulating cell-binded mast cells release mediators, for example, prostaglandin, leukotriene and histamine, subsequently enabling over secretion of mucus, contraction of the smooth muscle, inflammation and bronchi constriction. Shortness of breath, wheezing and gasping can be seen here (Dhawan & Kalluri, 2013).
 
 

The pathophysiology characteristic of intrinsic asthma is very similar to extrinsic asthma, it includes alike manifestation of T lymphocytes, in particular Th2 cytokines, and a comparable immune reaction, although people with intrinsic asthma have higher findings of RANTS (Cytokine) in the mucosa and increased bronchoalveolar fluid (Peters, 2014). 

Asthma is an obstructive lung disease characterised by acute symptomatic episodes of bronchial constriction that occur as a result of a homeostatic response due to a trigger or viral infection (Reveals & Katasos, 2011). According to the World Health Organisation asthma is one of the most common chronic diseases in the world affecting approximately 235 million people (2013). Asthma is believed to be an interaction between environmental and genetic factors causing one to become sensitized to environmental allergens (Tanaka & Takahashi, 2013). A randomized clinical trial that was undertaken in 2013 has made links with a Mediterranean Diet (which includes low intake of meaty and poultry moderate intake of oily fish and dairy products and high intake of fruits, whole grains vegetables, olive oil and legumes) and a reduced asthma risk (Sexton, et al., 2013). The below diagram demonstrates the immune response modulated by lipids either having a promotion on allergic reaction or protection against allergic reaction. One of the main elements leading to promotion of allergic reaction is medium-chain fatty acids (MCFA) that are saturated fatty acids found in oils like coconut oil (Julia, Macia, & Dombrowicz, 2015). Another link to controlling the body’s immune response to inflammation is in omega-6 and omega-3 polyunsaturated fattys acids (PUFAs). As seen in the diagram, Omega-6 PUFAs (found in foods such as meat, eggs, poultry etc.)  promote mast cell production (responsible for inflammatory response) where as omega-3 PUFAs (found in fish, vegetable oils, leafy vegetables etc.) decrease T cell responses (immune response to antigens) (Julia, Macia, & Dombrowicz, 2015). 
 
 More evidence from 2013 demonstrate a link between flavonoids (which are found in fruits, vegetables and beverages) and a decrease in the release of chemical mediators due to the antioxidant and anti-allergic traits (Tanaka & Takahashi, 2013). Although some of these human clinical trials are limited, there is some strong evidence to suggest dietary intervention could propose prevention and alleviation of allergic disease including asthma (Julia, Macia, & Dombrowicz, 2015). Changing a diet for an individual not only poses less adverse side effects in comparison to other asthma treatments it has proven health benefits beyond asthma (Sexton, et al., 2013). 
 
Image retrieved from: (Julia, Macia, & Dombrowicz, 2015).

Stronger evidence with higher quality research methodology which can draw conclusions based on causation and not correlation would provide greater reliability and support for the link between diet and asthma management. Below is a summary of evidence of particular dietary interventions and their effects on asthma.

 

Through the material that has been gathered from both sides of the topic, ‘Diet is a key factor in asthma management, and needs to be modified to reduce the risk of asthma exacerbations’,it can be believed that nurses who perform using evidence-based practices will disagree with the statement. Even though there is supportive evidence towards the connection involving consumption of various foods and amendments of asthma symptoms there is limited data to support this statement, hence why the nurse would be unable to agree with this statement.

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