Bronchitis is an inflammation of the mucous membranes of the deep inner lung passages called the bronchial tree.
Bronchitis may be either acute or chronic. Acute bronchitis is frequently caused by a viral or bacterial infection. Acute bronchitis may also result from irritation of the mucous membranes by environmental fumes, acids, solvents, or tobacco smoke. Bronchitis usually begins with a dry, nonproductive cough. After a few hours or days, the cough may become more frequent and produce mucus. A secondary bacterial infection may occur, in which the sputum (bronchial secretions) may contain pus. People whose cough and/or fever continues for more than seven days should visit a medical practitioner.
Chronic bronchitis may result from prolonged exposure to bronchial irritants. Cigarette smoking, environmental toxins, and inhaled allergens can all cause chronic irritation of the bronchi. The cells lining the bronchi produce excess mucus in response to the chronic irritation; this excess mucus production can lead to a chronic, productive cough.
Bronchitis can be particularly dangerous in the elderly and in people with compromised immune systems. These people should see a doctor if they develop a respiratory infection.
What are the symptoms of bronchitis?
Acute infectious bronchitis is often preceded by signs of an upper respiratory tract infection: stuffy or runny nose, malaise, chills, fever, muscle pain, and sore throat. The cough is initially dry and does not produce mucus. Later, small amounts of thick green or green-yellow sputum may be coughed up.
Chronic bronchitis is characterized by a productive cough that initially occurs only in the morning.
Dietary changes that may be helpful for bronchitis
Dietary factors may influence both inflammatory activity and antioxidant status in the body. Increased inflammation and decreased antioxidant activity may each lead to an increased incidence of chronic diseases, such as chronic bronchitis. People suffering from chronic bronchitis may experience an improvement in symptoms when consuming a diet high in anti-inflammatory fatty acids, such as those found in fish. In a double-blind study of children with recurrent respiratory tract infections, a daily essential-fatty-acid supplement (containing 855 mg of alpha-linolenic acid and 596 mg of linoleic acid) reduced both the number and the duration of recurrences.1
In people with bronchitis, lipids in the lung tissue may undergo oxidation damage (also called free-radical damage), particularly when the bronchitis is a result of exposure to environmental toxins or cigarette smoke. A diet high in antioxidants may protect against the free radical-damaging effect of these toxins. Studies comparing different populations have shown that increasing fruit and vegetable (and therefore, antioxidant) consumption may reduce the risk of developing chronic bronchitis.2 3
Food and environmental allergies may be triggering factors in some cases of chronic bronchitis.4 Cows’ milk allergy has been associated with bronchitis in children,5 6 7 and some doctors believe that dairy products may increase mucus production and, therefore, that people suffering from either acute or chronic bronchitis should limit their intake of dairy products. Ingestion of simple sugars (such as sucrose or fructose) can lead to suppression of immune function;8 therefore, some doctors believe simple sugars should be avoided during illness.
Lifestyle changes that may be helpful for bronchitis
Breast-feeding provides important nutrients to an infant and improves the functioning of the immune system. Studies have shown that breast-feeding prevents the development of lower respiratory tract infections during infancy.9 10 Whether that protective effect persists into adulthood is not known. Exposure to environmental chemicals, including passive smoke, can increase the incidence of respiratory illness among children.11
Chronic bronchitis is frequently associated with smoking and/or environmental exposure to chemicals or allergens. These exposures should be avoided to allow the cells of the bronchi to recover from chronic irritation and to decrease the burden on the immune system.
Nutritional supplements that may be helpful for bronchitis
In a double-blind study of elderly patients hospitalized with acute bronchitis, those who were given 200 mg per day of vitamin C improved to a significantly greater extent than those who were given a placebo.12 The common cold may lead to bronchitis in susceptible people, and numerous controlled studies, some double-blind, have shown that vitamin C supplements can decrease the severity and duration of the common cold in otherwise healthy people.13
Vitamin C and vitamin E may prevent oxidative damage to the lung lipids by environmental pollution and cigarette smoke exposure. It has been suggested that amounts in excess of the RDA (recommended dietary allowance) are necessary to protect against the air pollution levels currently present in North America,14 although it is not known how much vitamin E is needed to produce that protective effect.
A review of 39 clinical trials of N-acetyl cysteine (NAC) found that 400 to 600 mg per day was a safe and effective treatment for chronic bronchitis.15 NAC supplementation was found to reduce the number of aggravations of the illness in almost 50% of people taking the supplement, compared with only 31% of those taking placebo. Smokers have also been found to benefit from taking NAC.16 In addition to helping break up mucus, NAC may reduce the elevated bacterial counts that are often seen in the lungs of smokers with chronic bronchitis.17 In another double-blind study, people with chronic bronchitis who took NAC showed an improved ability to expectorate and a reduction in cough severity.18 These benefits may result from NAC’s capacity to reduce the viscosity (thickness) of sputum.19
Vitamin A levels are low in children with measles,20 an infection that can result in pneumonia or other respiratory complications. A number of studies have shown that supplementation with vitamin A decreased complications and deaths from measles in children living in developing countries where deficiencies of vitamin A are common.21 However, little to no positive effect, and even slight adverse effects, have resulted from giving vitamin A supplements to prevent or treat infections in people living in countries where most people consume adequate amounts of vitamin A.22 23 24 25 26 27 Therefore, vitamin A supplements may only be useful for people with bronchial infections who are known to be deficient in vitamin A.
The thymus gland plays a number of important roles in the functioning of the immune system. Thymus extract from calves, known as Thymomodulin®, has been found, in a double-blind study, to decrease the frequency of respiratory infections in children who were prone to such infections.28 The amount of Thymomodulin used in that study was 3 mg per kg of body weight per day.
Are there any side effects or interactions with bronchitis?
Refer to the individual supplement for information about any side effects or interactions.
Herbs that may be helpful for bronchitis
Several types of herbs may help people with bronchitis, either by treating underlying infection, by relieving inflammation, or by relieving symptoms such as cough. For clarity, the table below summarizes which herbs are in each category of action. Some herbs have more than one action. Herbs listed in the table have not necessarily been proven to be effective. The herbs are discussed in more detail following the table.