Asthma is a chronic condition in which the airways are inflamed and narrowed. The inflamed airways may produce extra mucus which makes it difficult to breathe.
Causes of Asthma
The exact cause of asthma is unclear. However, several factors may play an important role in developing asthma, including environmental and genetic factors such as a family history of asthma, socioeconomic status, tobacco smoke, allergens, urbanization, pollution and respiratory infections.
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Genetics:
Genetics may play an important role in the development of asthma. Studies have shown that genetics may increase the risk of asthma by about 70%. A person is likely to get asthma if he or she has a family history of asthma. This is common in people who are diagnosed with childhood asthma. However, everyone with a family history of asthma doesn't need to at some point in life get affected with it.
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Poor immunity and infections:
People with poor immunity are more likely to be prone to infections. With poor immunity, the body is unable to fight the pathogens (microbes) responsible for various infections. People who often get respiratory infections are more likely to get asthma. This is true for infants diagnosed with asthma. Due to poor immunity, kids are more likely to develop infections and asthma.
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Allergies:
Allergy is a condition in which our body abnormally responds to foreign particles. Different people will be allergic to different substances. Among all the allergens (foreign particles) known, the majority of people are either allergic to some foods, dust or weather changes. Some people with allergies may develop asthma. 90% of the children with asthma have some food allergies.
Also, people who are working in bakeries, coal mines, wood, paint, or chemical factories are regularly exposed to dust and smoke. On long-term exposure to these dust and chemicals, the body might become allergic to them, which may lead to asthma.
Also, some people may show asthma symptoms in a particular season such as cold and dry seasons. This is termed seasonal asthma.
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Irritants:
People working in cold mine industries or cooking with wood fire stoves may be exposed to the irritants that may cause airway and lung inflammation. Also, when people smoke, the irritants directly reach the lungs and may cause inflammation and irritation in the lungs and airways which may cause asthma.
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Air pollution:
Breathing in the polluted air may irritate the airways which may further lead to swelling (inflammation) and narrowing of the airways. When the airway narrow, the air that reaches the lungs is restricted or limited leading to the symptoms of asthma such as wheezing, shortness of breath and chest tightness.
Air pollution also causes upper respiratory problems such as cold, sinusitis, pharyngitis, etc., which may lead to asthma.
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Smoking:
Cigarette or nicotine smoking can cause many health-related problems. Smoking may cause inflammation in the airways and lungs which may not only cause airway narrowing but also damage the cells. Also, smoking during pregnancy may cause decreased lung function in the unborn which may contribute to their asthma. Studies have also shown that children whose parents smoke or are exposed to secondhand smoking (passive smoking)are at a greater risk of developing childhood asthma.
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Narrow airways:
People with narrow airways will have a lesser capacity to carry oxygen. This could be one of the reasons why a majority of asthma cases are seen in children below the age of five years.
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Hormones:
Another cause of asthma could be hormones. Studies have shown that females are more likely to get asthma than males due to their hormones.
Triggering factors
People with asthma may not have the symptoms all the time. Some triggering factors may lead to their symptoms or exacerbations.
The most common ones include-
- Exposure to allergens such as grass, plants, house dust, cockroaches, pollen grains, animal fur
- Cold air
- Tobacco smoking
- Wood smoke
- Emotional state (anxiety, stress, laugh)
- Exercise or physical activity: Some people show asthma-like symptoms such as cough, wheezing, breathlessness or chest tightness only after being exposed to strenuous (vigorous) exercise. This is also termed exercise-induced bronchospasm. However, exercise will not cause asthma.
- Certain drugs (particularly aspirin and other NSAIDs)
- Occupational status of a person: Bakers, farmers, printers, painters, plastics, rubber, and woodworkers, people working in chemical factories are more prone to asthma.
Other causes and factors responsible for asthma:
- High blood sugar levels (diabetic people): People with high blood sugar levels may be at a higher risk of developing asthma.
- Vitamin deficiency- Studies have shown that deficiency of some vitamins like vitamin C, E and D may not only play an important role in developing asthma but may also have an impact on the severity and frequency of asthma attacks.
- Deficiency of antioxidants- People with asthma may show oxidative stress (i.e., there is an increased level of free radicals that are harmful to our body). Antioxidants are chemicals that prevent the generation of free radicals and their harmful effects. A few important antioxidants include some vitamins (like vitamins A, E and C), minerals (like magnesium, zinc and selenium), glutathione, etc.
References:
- Quirt J, Hildebrand KJ, Mazza J, Noya F, Kim H. Asthma. Allergy Asthma. Clin Immunol. 2018 Sep 12;14(Suppl 2):50. doi: 10.1186/s13223-018-0279-0. PMID: 30275843; PMCID: PMC6157154.
- Ariaee N, Farid R, Shabestari F, Shabestari M, Jabbari Azad F. Trace Elements Status in Sera of Patients with Allergic Asthma. Rep Biochem Mol Biol. 2016 Oct;5(1):20-25. PMID: 28070530; PMCID: PMC5214679.
- Guo C-H, Liu P-J, Hsia S, Chuang C-J, Chen P-C. Role of certain trace minerals in oxidative stress, inflammation, CD4/CD8 lymphocyte ratios and lung function in asthmatic patients. Annals of Clinical Biochemistry. 2011;48(4):344-351.
