Asthma is a lung disorder in which spasms and inflammation of the bronchial passages restrict the flow of air in and out of the lungs.
The number of people with asthma and the death rate from this condition have been increasing since the late 1980s. Environmental pollution may be one of the causes of this growing epidemic. Work exposure to flour or cotton dust, animal fur, smoke, and a wide variety of chemicals has been linked to increased risk of asthma.1
Findings from animal and human studies confirm that DTP (diphtheria and tetanus toxoids and pertussis) and tetanus vaccinations can induce allergic responses,2 3 4 5 6 and can increase the risk of allergies, including allergic asthma. An analysis of data from nearly 14,000 infants and children revealed that having a history of asthma is twice as great among those who were vaccinated with DTP or tetanus vaccines than among those who were not.7
What are the symptoms of asthma?
An asthma attack usually begins with sudden fits of wheezing, coughing, or shortness of breath. However, it may also begin insidiously with slowly increasing manifestations of respiratory distress. A sensation of tightness in the chest is also common.
Dietary changes that may be helpful for asthma
A vegan (pure vegetarian) diet given for one year in conjunction with many specific dietary changes (such as avoidance of caffeine, sugar, salt, and chlorinated tap water) and combined with a variety of herbs and supplements led to significant improvement in one group of asthmatics.8 Although 16 out of 24 people who continued the intervention for the full year were much better and one person was actually cured, it remains unclear how much of the action was purely a result of the dietary changes compared with the many other therapies employed.
Vitamin C, an antioxidant present in fruits and vegetables, is a powerful antioxidant and anti-inflammatory. This anti-inflammatory activity may influence the development of asthma symptoms. A large preliminary study has shown that young children with asthma experience significantly less wheezing if they eat a diet high in fruits rich in vitamin C.9
Studies suggest that high salt intake may have an adverse effect on asthma, particularly in men. In a small, preliminary trial, doubling salt intake for one month led to a small increase in airway reactivity (indicating a worsening of asthma) in men with asthma, as well as in non-asthmatics.10 Several double-blind trials have provided limited evidence of clinical improvement following a period of sodium restriction.11 12 13 14 It is difficult to compare the results of these studies because they used different amounts of sodium restriction. However, they consistently suggest that increased dietary sodium may aggravate asthma symptoms, especially in men.15
Although most people with asthma do not suffer from food allergies,16 unrecognized food allergy can be an exacerbating factor.17 A medically supervised “allergy elimination diet,” followed by reintroduction of the eliminated foods, often helps identify problematic foods. A healthcare professional must supervise this allergy test because of the possibility of triggering a severe asthma attack during the reintroduction.18
Some asthmatics react to food additives, such as sulfites, tartrazine (yellow dye #5), and sodium benzoate, as well as natural salicylates (aspirin-like substances found in many foods).19 20 A doctor or an allergist can help determine whether chemical sensitivities are present.
Lifestyle changes that may be helpful for asthma
Being overweight increases the risk of asthma.21 Obese people with asthma may improve their lung-function symptoms and overall health status by engaging in a weight-loss program. A controlled study found that weight loss resulted in significant decreases in episodes of shortness of breath, increases in overall breathing capacity, and decreases in the need for medication to control symptoms.22
Nutritional supplements that may be helpful for asthma
Lycopene, an antioxidant related to beta-carotene and found in tomatoes, helps reduce the symptoms of asthma caused by exercising. In one double-blind trial,23 over half of people with exercise-induced asthma had significantly fewer asthma symptoms after taking capsules containing 30 mg of lycopene per day for one week compared to when they took a placebo.
Vitamin B6 deficiency is common in asthmatics.24 This deficiency may relate to the asthma itself or to certain asthma drugs (such as theophylline and aminophylline) that deplete vitamin B6.25 In a double-blind trial, 200 mg per day of vitamin B6 for two months reduced the severity of asthma in children and reduced the amount of asthma medication they needed.26 In another trial, asthmatic adults experienced a dramatic decrease in the frequency and severity of asthma attacks while taking 50 mg of vitamin B6 twice a day.27 Nonetheless, the research remains somewhat inconsistent, and one double-blind trial found that high amounts of B6 supplements did not help asthmatics who required the use of steroid drugs.28
Magnesium levels are frequently low in asthmatics.29 Current evidence suggests that high dietary magnesium intake may be associated with better lung function and reduced bronchial reactivity. Intravenous injection of magnesium has been reported in most,30 31 32 33 but not all,34 double-blind trials to rapidly halt acute asthma attacks. Magnesium supplements might help prevent asthma attacks because magnesium can prevent spasms of the bronchial passages. In a preliminary trial, 18 adults with asthma took 300 mg of magnesium per day for 30 days and experienced decreased bronchial reactivity.35 However, a double-blind trial investigated the effects of 400 mg per day for three weeks and found a significant improvement in symptoms, but not in objective measures of airflow or airway reactivity.36 The amount of magnesium used in these trials was 300 to 400 mg per day (children take proportionately less based on their body weight).
Supplementation with 1 gram of vitamin C per day reduces the tendency of the bronchial passages to go into spasm,37 an action that has been confirmed in double-blind research.38 Beneficial effects of short-term vitamin C supplementation (i.e., less than three days) have been observed. In one double-blind trial, 500 mg of vitamin C per day for two days prevented attacks of exercise-induced asthma.39 Two other preliminary trials found that vitamin C supplementation reduced bronchial reactivity to metacholine, a drug that causes bronchial constriction.40 41 However, other studies,42 including two double-blind trials,43 44 have failed to corroborate these findings. The only double-blind trial of a long duration found that vitamin C supplementation (1 gram per day for 14 weeks) reduced the severity and frequency of attacks among Nigerian adults with asthma.45 A buffered form of vitamin C (such as sodium ascorbate or calcium ascorbate) may work better for some asthmatics than regular vitamin C (ascorbic acid).46
People with low levels of selenium have a high risk of asthma.47 48 49 50 51 Asthma involves free-radical damage52 that selenium might protect against. In a small double-blind trial, supplementation with 100 mcg of sodium selenite (a form of selenium) per day for 14 weeks resulted in clinical improvement in six of eleven patients, compared with only one of ten in the placebo group.53 Most doctors recommend 200 mcg per day for adults (and proportionately less for children)—a much higher, though still safe, level.
Double-blind research shows that fish oil partially reduces reactions to allergens that can trigger attacks in some asthmatics.54 Although a few researchers report small but significant improvements when asthmatics supplement with fish oil,55 56 reviews of the research show that most fish oil studies with asthmatics come up empty-handed.57 58 It is possible that some of these trials failed because they did not last long enough to demonstrate an effect. There is evidence that children who eat oily fish may have a much lower risk of getting asthma.59 Moreover, in a double-blind trial, children who received 300 mg per day of fish oil (providing 84 mg of EPA and 36 mg of DHA) experienced significant improvement of asthma symptoms.60 It should be noted that these benefits were obtained under circumstances in which exposure to food allergens and environmental allergens was strictly controlled. Though the evidence supporting the use of fish oil remains somewhat conflicting, eating more fish and supplementing with fish oil may still be worth considering, especially among children with asthma.
In a double-blind study of people with asthma, supplementation with a proprietary extract of New Zealand green-lipped mussel (Lyprinol®) twice a day for 8 weeks significantly decreased daytime wheezing and improved airflow through the bronchi.61 Each capsule of Lyprinol® contains 50 mg of omega-3 fatty acids.
A study conducted many years ago showed that 80% of children with asthma had hypochlorhydria (low stomach acid). Supplementation with hydrochloric acid (HCl) in combination with avoidance of known food allergens led to clinical improvement in this preliminary trial.62 In more recent times, HCl has usually been supplemented in the form of betaine HCl. The amount needed depends on the severity of hypochlorhydria and on the size of a meal. Because it is a fairly strong acid, betaine HCl should be used only with medical supervision.
In some people with asthma, symptoms can be triggered by ingestion of food additives known as sulfites. Pretreatment with a large amount of vitamin B12 (1,500 mcg orally) reduced the asthmatic reaction to sulfites in children with sulfite sensitivity in one preliminary trial.63 The trace mineral molybdenum also helps the body detoxify sulfites.64 While some doctors use molybdenum to treat selected patients with asthma, there is little published research on this treatment, and it is not known what an appropriate level of molybdenum supplementation would be. A typical American diet contains about 200 to 500 mcg per day,65 and preliminary short-term trials have used supplemental amounts of 500 mcg per day.66 People who suspect sulfite-sensitive asthma should consult with a physician before taking molybdenum.
Quercetin, a flavonoid found in most plants, has an inhibiting action on lipoxygenase, an enzyme that contributes to problems with asthma.67 No clinical trials in humans have confirmed whether quercetin decreases asthma symptoms. Some doctors are currently experimenting with 400 to 1,000 mg of quercetin three times per day.
Bromelain reduces the thickness of mucus, which may be beneficial for those with asthma,68 though clinical actions in asthmatics remain unproven.
Some researchers have suggested that asthma attacks triggered by exercise might be caused by free-radical damage caused by the exercise. Beta-carotene is an antioxidant that protects against free-radical damage. Israeli researchers reported that 64 mg per day of natural beta-carotene for one week in a double blind trial protected over half of a group of asthmatics who experienced attacks as a result of exercise.69 More research is needed to confirm this promising finding.
The oral administration of a thymus extract known as thymomodulin has been shown in preliminary and double-blind clinical trials to improve the symptoms and course of asthma.70 71 72 73 Presumably this clinical improvement is the result of restoration of proper control over immune function.
Are there any side effects or interactions with asthma?
Refer to the individual supplement for information about any side effects or interactions.
Herbs that may be helpful for asthma
There are two categories of herbs generally used for people with asthma. These are herbs that help dilate the airways and herbs that are anti-inflammatory. Herbs in each category are summarized in the table below.
Eclectic physicians—doctors in turn-of-the-century North America who used herbs as their main medicine—considered lobelia to be one of the most important plant medicines.74 Traditionally, it was used by Eclectics to treat coughs and spasms in the lungs from all sorts of causes.75 A plant that originates in Africa, khella, is also considered an anti-spasmodic like lobelia. Though it is not strong enough to stop acute asthma attacks, khella has been recommended by German physicians practicing herbal medicine as possibly helpful for chronic asthma symptoms.76
One double-blind trial has investigated the effects of the Ayurvedic herb boswellia in people with acute bronchial asthma.77 Participants took 300 mg of powdered boswellia resin extract or placebo three times daily for six weeks. By the end of the study, the number of asthma attacks was significantly lower in the group taking boswellia. Moreover, objective measurements of breathing capacity were also significantly improved by boswellia.
Two preliminary trials have shown picrorhiza to be of benefit in asthma.78 79 However, a follow-up double-blind trial did not confirm these earlier results.80 A range of 400 to 1,500 mg of powdered, encapsulated picrorhiza per day has been used in a variety of trials. It remains unclear how effective picrorhiza is for people with asthma.
Different preparations of tylophora, including crude leaf, tincture, and capsule, have been tested in human clinical trials. One double-blind trial had people with bronchial asthma chew and swallow one tylophora leaf (150 mg of the leaf by weight) per day for six days. Participants were also given a comparable placebo to be chewed and swallowed during a different six-day period. When consuming tylophora, over half of the people reported experiencing moderate to complete relief of their asthma symptoms, compared to only about 20% reporting relief when consuming the placebo.81 In a follow-up double-blind trial, an alcoholic extract of crude tylophora leaves had comparable effects to that of chewing the crude leaf.82 Another double-blind trial found 350 mg of tylophora leaf powder per day increased the lungs’ capacity for oxygen and reduced nighttime shortness of breath, but was not as effective as an antiasthmatic drug combination.83 A fourth double-blind trial found no significant changes in lung volume measurements or asthmatic symptoms after treatment with 400 mg per day tylophora.84
A controlled trial on children with bronchial asthma suggested that 25 drops of ivy leaf extract given twice daily was effective in increasing the amount of oxygen in the lungs after only three days of use. However, the frequency of cough and shortness of breath symptoms did not change during the short trial period.85
Ginkgo biloba extracts (GBE) have been considered a potential therapy for asthma. This is because the extracts block the action of platelet-activating factor (PAF), a compound the body produces that in part causes asthma symptoms. A trial using isolated ginkgolides from ginkgo (not the whole extract) found they reduced asthma symptoms.86 A controlled trial used a highly concentrated tincture of ginkgo leaf and found this preparation helped decrease asthma symptoms.87 For asthma, 120 to 240 mg of standardized GBE or 3 to 4 ml of regular tincture three times daily can be used.
In three preliminary trials on people with asthma, a traditional Japanese herbal formula known as saiboku-to has been shown to reduce symptoms and enable some people to reduce their use of steroid medication.88 89 90 Saiboku-to has been extensively studied in the laboratory and has been shown to have numerous anti-inflammatory actions.91 Some of these studies used 2.5 grams three times per day of saiboku-to. A traditional Chinese or Japanese medicine practitioner should be consulted for more information. Saiboku-to contains bupleurum, hoelen, pinellia, magnolia, Asian ginseng, Asian scullcap, licorice, perilla, ginger and jujube.
Onion may act as an anti-inflammatory in people with asthma. Human studies have shown onion can be a strong anti-inflammatory.92 However, some people with asthma may experience an exacerbation of symptoms if they are allergic to onion and are exposed to it.93
Traditionally, herbs that have a soothing action on bronchioles are also used for asthma. These include marshmallow, mullein, hyssop, and licorice. Elecampane has been used traditionally to treat coughs associated with asthma.94
Are there any side effects or interactions with asthma?
Refer to the individual herb for information about any side effects or interactions.
Holistic approaches that may be helpful for asthma
A set of breathing exercises called Buteyko breathing techniques has been reported to significantly reduce the need for prescription drugs for people with asthma.95 Although the people in this controlled trial experienced an improved quality of life while doing these exercises, objective measures of breathing capacity did not improve, despite the decreased need for drugs.
Antibiotic use during the first year or two of life has been associated with an increased risk of asthma in preliminary studies.96 97 Whether this association might result from allergic versus non-allergic effects remains unknown. However, the association does suggest that, until more is known, gratuitous use of antibiotics in early childhood (e.g., to inappropriately treat viral diseases) should be reconsidered. Of course, the appropriate use of antibiotics in the treatment of infections as necessary should not be avoided. Concerns should be discussed with the prescribing physician.
Acupuncture might be useful for some asthmatics. Case reports98 99 and preliminary trials100 101 102 have suggested acupuncture may be helpful for people with asthma, either as a treatment for an acute attack or as a longer term therapy for reducing the number or severity of attacks, decreasing the need for medications, and so on. Placebo-controlled trials using sham (“fake”) acupuncture, however, have been quite contradictory, many of them showing a strong placebo effect that is not significantly improved upon by real acupuncture.103 104 105 106 It is possible that needle insertion in non-acupuncture points has a stimulating effect that benefits asthma. The success of acupuncture may also depend on other factors, such as the type of asthma being treated and certain characteristics of the patient. Nonetheless, since some controlled research has demonstrated positive effects of real acupuncture, people with asthma may want to consider a trial of acupuncture treatment to see if it helps their individual cases.
Chiropractic physicians have reported that manipulation may be helpful for patients with asthma.107 108 109 In a controlled study, chronic asthmatics received either real or sham chiropractic manipulations for four weeks, after which the treatments were switched for another four weeks. No improvement in measurements of lung function was found at the end of the study. In addition, while both the manipulation and the sham treatment groups reported significant decreases in asthma frequency and severity, there were no differences between the treatments.110 A larger controlled study compared chiropractic manipulation to sham manual treatments in children whose asthma was still a problem despite usual medical management.111 Both groups experienced a significant decrease in symptoms and need for medication, as well as small increases in ability to breathe. These benefits lasted for four months after the treatments were discontinued. Although there was no additional benefit of chiropractic compared to the sham treatments, it is possible that improvements in both groups were real, rather than placebo effects. The sham therapy, which consisted of “soft tissue massage and gentle palpation [touching],” may have had real effects. More research is needed to address this confusing issue.