The definition of lung disease is an inability for the lungs to function properly due to decreased functioning of either the airways, tissue or circulation. Circulatory diseases decrease the ability of the lungs to take up oxygen and release carbon dioxide because blood vessels are subject to significant degrees of clotting, scarring and inflammation.
Tissue diseases degrade the structural components of the lungs, leading to severe tissue damage that prevents the full expansion of the lungs. Airway diseases cause a narrowing or blockage of the airways, reducing oxygen intake and the emission of gas within the body.
What are the main types of lung disease?
- Asthma – Described as frequent attacks of breathlessness and wheezing. The severity of asthma ranges greatly between individuals. Effects can occur hourly or daily, dependent on genetic predispositions to asthmatic attack frequency. Asthma irritates nerve endings within the airways by increasing their sensitivity, primarily caused via inflammation. Asthma attacks occur when the airways narrow to a point where air intake is significantly decreased, due to swelling of the lining within airway passages.
- Chronic Obstructive Pulmonary Disease (COPD) – A term used to describe a group of chronic lung diseases that negatively affect the airflow in the lungs. It develops from an inflammatory and destructive process in the lungs accelerated by exposure to toxins (such as smoking). The main lung conditions that are defined as COPD are bronchitis and emphysema. Bronchitis is the inflammation and narrowing of the airways, typically leading to phlegm production. Emphysema targets a more specific area in the lungs, the air sacs in the airways, where the air sacs are slowly broken down. This process creates holes that trap air and subsequently narrow the airways.
Stop smoking, immediately
Cigarette smoking is the major etiological factor in lung conditions. An increased oxidant burden in smokers derives from the fact that cigarette smoke contains more than 1017 free radicals and oxidant molecules per puff . A study suggested that cigarette smoking depletes an array of multiple antioxidants needed to kill the free radicals present in cigarette smoke, which plays a key role in the development and worsening of lung diseases . A lack of antioxidants also impedes the inflammatory response induced by cigarette smoking. More than 90% of patients with COPD are smokers, and ~15%–20% of cigarette smokers show a rapid decline in forced expiratory volume (maximum volume of air that can be forced out in one second) and develop lung disease .
Can nutrition help those with lung disease?
Nutrition has not yet been shown to fully reverse the onset of lung disease, but it certainly has a key role in managing the symptoms and taking control of the disease.
Proper nutrition helps to reduce carbon dioxide levels in the body and improve breathing. Dietary changes can treat excessive breathing, a trait of those with lung disease, which can lead to carbon dioxide (CO2) deficit in the blood (hypocapnia) because of increased ventilation. This can cause physiological changes such as an oxygen deficit, cerebral vasoconstriction and coronary constriction. Based on this, reducing an individual’s respiratory quotient (RQ), which is defined as the ratio of carbon dioxide produced to oxygen consumed, can improve breathing. Reducing the RQ, therefore, decreases the amount of CO2 produced in the body, thereby reducing the amount of energy spent on respirations. The ratio of carbon dioxide produced to oxygen consumed is different depending on the macronutrient. The RQ for carbohydrate is 1, protein is 0.8, and fat is 0.7. Those with lung disease should, therefore, look to decrease their carbohydrate intake, and replace this source of calories with a fat or protein based food source. A study noted that comparatively small changes in the carbohydrate and fat constitution of meals can have a significant effect on carbon dioxide production, exercise tolerance, and breathlessness in patients with COPD .
The American Dietetic Association also recommends avoid overfeeding (consuming excess calories) if an individual has lung disease, as it will cause unnecessary CO2 production and create problems that can easily be avoided . High-calorie intakes, especially as carbohydrate, can result in CO2 deficit in the blood and raises the likelihood of respiratory failure in patients with severe pulmonary disease.
In addition, recent animal studies highlight the link between gut health and the development of chronic lung diseases. Mice that have low levels of circulating short-chain fatty acids, the end product of dietary fibre metabolism, exhibit an exaggerated disease development in models of allergic airway inflammation . This is theorised to be mainly due to diets high in fibre being protective against chronic inflammation, as well as decreasing the incidence of allergy and autoimmunity.
Are supplements effective at treating lung disease?
A meta-analysis showed that clinically-diagnosed asthmatics who supplemented vitamin D have 50% a number of asthma attacks per year, as well as 50% the chance of needing a hospital admission from an asthma attack, compared to those that did not supplement vitamin D . Vitamin D can help to reduce upper respiratory infections (i.e a cold) that can exacerbate asthmatic effects, as well as reduce inflammation in the airways. Public Health England recommends 10 micrograms of vitamin D per day, which can be achieved from adequate sunlight . However, Harvard University predicts 1 billion people are deficient in vitamin D and therefore supplementation may be necessary, especially for those who live in areas with low sunlight .
Dietary antioxidant supplementation is also a great method to encourage healthier antioxidant defence systems. Even in individuals that do not have lung disease, there is a positive association between dietary intake of antioxidant vitamins and lung function . The evidence behind certain antioxidants and their benefits is constantly growing:
- Polyphenols have evidence to support its therapeutic use at preventing or inhibiting oxidative stress and inflammatory responses .
- In smokers, specifically, an antioxidant mixture containing vitamin C, α-lipoic acid, and vitamin E significantly reduces plasma F2-isoprostane levels (measurement of oxidative stress), suggesting the regulation of lung oxidative stress with these dietary supplements .
- Astaxanthin has recently shown to prevent pulmonary fibrosis by promoting myofibroblast apoptosis. Comparable to cancer cells, myofibroblasts show epigenetic and genetic abnormalities, and therefore a supplement like Astaxanthin which promotes of the death of these cells is recommended .
- Turmeric and Green Tea are also recommended as they are very powerful antioxidants and promote immune health.
- Bernhard. D. . Cigarette Smoke Toxicity: Linking Individual Chemicals to Human Diseases, John Wiley & Sons
- Tsuchiya. M et al. . Smoking a single cigarette rapidly reduces combined concentrations of nitrate and nitrite and concentrations of antioxidants in plasma, Circulation
- Snider. GL. . Chronic obstructive pulmonary disease: risk factors, pathophysiology and pathogenesis, Ann Rev Med.
- Efthimiou. J et al. . Effect of carbohydrate rich versus fat rich loads on gas exchange and walking performance in patients with chronic obstructive lung disease, Thorax
- Nelms. M et al. . Nutrition Therapy and Pathophysiology, Cengage Learning
- Marsland, BJ et al. . Immune system dysregulation in chronic lung disease, European Respiratory Journal
- Martineau. AR et al. . Vitamin D for the management of asthma, Cochrane Database of Systematic Reviews
- Scientific Advisory Commission on Nutrition. . Vitamin D and Health, Crown
- Vitamin D and Health. . Available from: https://www.hsph.harvard.edu/nutritionsource/vitamin-d/
- Grievink. L et al. . Dietary intake of antioxidant (pro)-vitamins, respiratory symptoms and pulmonary function: the MORGEN study, Thorax
- Mitjavila. MT et al. . The effects of polyphenols on oxidative stress and the arachidonic acid cascade. Implications for the prevention/treatment of high prevalence diseases, Biochem Pharmacol.
- Dietrich. M et al. . Antioxidant supplementation decreases lipid peroxidation biomarker F(2)-isoprostanes in plasma of smokers, Cancer Epidemiol Biomarkers Prev.
- Zhang. J et al. . Astaxanthin prevents pulmonary fibrosis by promoting myofibroblast apoptosis dependent on Drp1-mediated mitochondrial fission, J Cell Mol Med.