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.
Expectorant herbs help loosen bronchial secretions and make elimination of mucus easier. Numerous herbs are traditionally considered expectorants, though most of these have not been proven to have this effect in clinical trials. Anise contains a volatile oil that is high in the chemical constituent anethole and acts as an expectorant.29
Horehound has expectorant properties, possibly due to the presence of a diterpene lactone in the plant, which is known as marrubiin.30
Mullein has been used traditionally as a remedy for the respiratory tract, including bronchitis. The saponins in mullein may be responsible for its expectorant actions.31
Pleurisy root is an expectorant and is thought to be helpful against all types of respiratory infections. It is traditionally employed as an expectorant for bronchitis. However, owing to the cardiac glycosides it contains, pleurisy root may not be safe to use if one is taking (heart medications.32 This herb should not be used by pregnant women.
Anti-inflammatory herbs may help people with bronchitis. Often these herbs contain complex polysaccharides and have a soothing effect; they are also known as demulcents. Plantain is a demulcent that has been documented in two preliminary trials conducted in Bulgaria to help people with chronic bronchitis.33 34 Other demulcents traditionally used for people with bronchitis include mullein, marshmallow, and slippery elm. Because demulcents can provoke production of more mucus in the lungs, they tend to be used more often in people with dry coughs.35
Elecampane is a demulcent that has been used to treat coughs associated with bronchitis, asthma, and whooping cough. Although there have been no modern clinical studies with this herb, its use for these indications is based on its high content of soothing mucilage in the forms of inulin and alantalactone.36 However, the German Commission E monograph for elecampane does not approve the herb for bronchitis.37
Ivy leaf is approved in the German Commission E monograph for use against chronic inflammatory bronchial conditions.38 One double-blind human trial found ivy leaf to be as effective as the drug ambroxol for chronic bronchitis.39 Ivy leaf is a non-demulcent anti-inflammatory.
Chinese scullcap might be useful for bronchitis as an anti-inflammatory. However, the research on this herb is generally of low quality.40
Antimicrobial and immune stimulating herbs may also potentially benefit people with bronchitis. Echinacea is widely used by herbalists for people with acute respiratory infections. This herb stimulates the immune system in several different ways, including enhancing macrophage function and increasing T-cell response.41 Therefore, echinacea may be useful for preventing a cold, flu, or viral bronchitis from progressing to a secondary bacterial infection.
Thyme contains an essential oil (thymol) and certain flavonoids. This plant has antispasmodic, expectorant, and antibacterial actions, and it is considered helpful in cases of bronchitis.42 One preliminary trial found that a mixture containing volatile oils of thyme, mint, clove, cinnamon, and lavender diluted in alcohol, in the amount of 20 drops three times daily, reduced the number of recurrent infections in people with chronic bronchitis.43
Horseradish contains substances similar to mustard, such as glucosinolates and allyl isothiocynate.44 In addition to providing possible antibacterial actions, these substances may also have expectorant properties that are supportive for persons with bronchitis.
Eucalyptus leaf tea is used to treat bronchitis and inflammation of the throat,45 and is considered antimicrobial. In traditional herbal medicine, eucalyptus tea or volatile oil is often used internally as well as externally over the chest; both uses are approved for people with bronchitis by the German Commission E.46
Lobelia contains many active alkaloids, of which lobeline is considered the most active. Very small amounts of this herb are considered helpful as an antispasmodic and antitussive agent (a substance that helps suppress or ease coughs). Anti-inflammatory properties of the herb have been demonstrated, which may be useful, since bronchitis is associated with inflammation in the bronchi.47 Lobelia should be used cautiously, as it may cause nausea and vomiting.
Are there any side effects or interactions with bronchitis?
Refer to the individual herb for information about any side effects or interactions.