What is Asthma?
Asthma is a chronic, inflammatory, lung disease. The pathophysiology of asthma is complex and involves airway inflammation, intermittent airflow obstruction, and bronchial hyperresponsiveness. According to the Centers for Disease Control and Prevention, an estimated 25 million Americans have asthma, which causes about 3,500 deaths each year. It is also one of the most common chronic diseases in childhood, affecting an estimated 7 million children.
There is no known cure for asthma but many medications and changes in behavior (avoiding environmental triggers) are available to help manage the condition.
Causes and Symptoms
Asthma can be either allergic or non-allergic. Both allergic and non-allergic produce similar symptoms and lead to airway obstruction and inflammation that is partly reversible by medication. The main difference, however, is their cause.
- Allergic (extrinsic) asthma: Inhaled allergens like dust mites, mold spores, pollen, and pet dander may trigger allergic asthma. This type of asthma involves the immune system.
- Non-allergic (intrinsic) asthma: Non-allergic asthma is not related to allergies and does not involve the immune system. Instead, factors like anxiety, stress, exercise, cold air, dry air, smoke, hyperventilation, viruses, and other irritants trigger the disease.
Symptoms for both types of asthma typically include:
- Coughing (constantly or intermittently)
- Shortness of breath
- Chest tightness or chest pain
Guidelines from the National Asthma Education and Prevention Program highlight the importance of correctly diagnosing asthma, by establishing the following:
- Episodic symptoms of airflow obstruction are present
- Airflow obstruction or symptoms are at least partially reversible
- Exclusion of alternative diagnoses
Spirometry with postbronchodilator response should be obtained as the primary test to establish the asthma diagnosis.
The goal of managing asthma involves both reducing symptoms by maintaining near normal lung function and by prevention asthma exacerbations that can require emergency care and hospitalization. Minimizing exposure to environmental factors that can exacerbate asthma is a first step including known allergens, certain medications, pollutants, stress/emotions, exercise (for exercise induced asthma), certain food additives, and tobacco smoke exposure.
What is the Conventional Treatment?
Pharmacologic management includes the use of relief and control agents. Control agents include inhaled corticosteroids, inhaled cromolyn (Intal) or nedocromil (Tilade), long-acting bronchodilators, theophylline (Theo-24, Theochron, Uniphyl), leukotriene modifiers, and anti-IgE antibodies. Relief medications include short-acting bronchodilators, systemic corticosteroids, and ipratropium (Atrovent).
The pharmacologic treatment of asthma is based on stepwise therapy. Asthma medications should be added or deleted as the frequency and severity of the patient’s symptoms change.
Environmental exposures and irritants (dust mites, mold spores, pollen and pet dander) can play a strong role in symptom exacerbations. The use of skin testing or in vitro testing to assess sensitivity to indoor allergens is important. Once the offending allergens are identified, patients should be counseled on how best to avoid them.
Epidemiological data support an association between antioxidant intake in food and pulmonary function. While a mechanism of action has yet to be elucidated, it is thought that by reducing the oxidative insult to the lungs, antioxidants modulate the development of chronic lung disease. Some authors are suggesting consuming antioxidants at levels higher than the RDA is a necessity for those exposed to chronic air pollutants (city dwellers, cigarette smokers, those who vigorously exercise). ,
Among children, the consumption of fruit (especially vitamin C containing fruit) is inversely related to asthma prevalence and directly related to lung function. Asthma symptomology is reduced even at low levels of fruit consumption (1-2 servings a week). In a study of 18,162 participants, antioxidant levels (serum vitamin C, E, beta-carotene, and selenium) were significantly associated with FEV1(forced expiratory volume in 1 second). Other studies using 2526 participants and NHANES I data also correlated FEV1 with dietary vitamin C intake. Studies have shown that increasing vitamin C intake by 40 mg/day, leads to a 20-ml increase in FEV1.,
Supplemental studies have had conflicting results. In a small study of eight asthmatic subjects, supplemented with 1500 mg/day of ascorbic acid, in a placebo-controlled, crossover design, resulted in an improved FEV1 following exercise. A Cochrane review of vitamin C and athsma noted some studies showed improvements (especially in exercise-induced reductions in FEV1), while most had not.
While Boswellia has not been extensively studied for asthma, but some research has been performed. Boswellic acids (11-keto-beta-Boswellic acid and acetyl-11-keto-beta-boswellic acid) are known to alter production of certain cytokines, thus inhibiting NFkappaB, down regulating TNF-alpha, and IL-1, IL-2, Il-4, Il-6 and other proinflammatory cytokines along with mast cell stabilization that may account for its use in asthma. One small preliminary double-blind, placebo-controlled study reported a 70 percent decrease in symptoms (dyspnea, rhonchi, number of attacks) as well as subjective improvements (an increase in FEV subset1, FVC and PEFR, and a decrease in eosinophilic count and ESR) with supplementation (300 milligrams/TID).
Butterbur (Petasites hybridus) is an herbal medicine, traditionally used for inflammation that has exhibited both antihistamine and antileukotriene activity. In a small open-pilot study of 64 adults and children with asthma, the number, severity, and duration of attacks decreased, while peak flow, FEV1 improved during therapy. The study also reported that 40 percent of patients reduced use of standard medications while supplementing with Butterbur. In another double-blind, crossover study of atopic patients taking 50 mg/TID, inflammation (determined via cutaneous wheal and flare response) was not reduced in the group supplementing with Butterbur. In another study, patients maintained on standard therapy and Butterbur used as an add-on therapy, supplementing with butterbur reduced many assessments of inflammation when compared to those taking only standard therapy.
Fish oil (EPA/DHA) is well researched for its effects on inflammation. In a Double blind trial of 3.2g EPA, 2.2 g DHA/day supplemented to 17 atopic asthmatic subjects, the response to allergy challenge was attenuated in supplemental group, although there were no changes in symptomology. The results of a 10-month trail in 29 children with bronchial asthma, demonstrated decreased responsiveness to acetylcholine challenge in the fish oil supplemented group. In exercise-induced asthma, 15 asthmatic patients were supplemented with 3.2g EPA and 2.0g DHA or placebo. There was improved pulmonary function along with decreased bronchodilator use in supplemented group.
The Cochrane group reviewed the evidence in 2002 and cited strong epidemiological studies suggest a strong correlation between marine fatty acids and inflammatory conditions (asthma/rheumatoid arthritis). In the nine trails that were included in the review, they suggested that information was not consistent enough to recommend fish oil for use.
Ginger contains compounds that have potential to induce relaxation of airway smooth muscle (6-gingerol, 8-gingerol, or 6-shogaol and others) that work mainly through modulating cytokines and calcium influx regulation, but research has been limited and there are no clinical trials to date.,
Laboratory studies have confirmed anti-inflammatory properties, as well as inhibition of platelet activating factor (PAF) for extracts of ginkgo (Ginkgolide B). Animal studies have suggested alleviation of chronic lung histological changes (except smooth muscle thickness) with administration of Ginkgo. In a clinical trial (n = 75), supplementing with Ginkgo (along with fluticasone propionate) decreased inflammation as measured by the level of IL-5 in sputum, when compared to those treated with fluticasone propionate alone. Large clinical trials are needed to confirm a reduction in asthmatic symptomology, but these preliminary studies are intriguing.
Grape Seed Extract
Grape seed extract is known to possess a strong antioxidant and anti-inflammatory effects. In animal studies, it has been shown to ameliorate pathological changes, reduce inflammation, decrease IL-4, IL-5, IL-13, and airway hyperresponsiveness in allergic asthma models. ,
Lycopene is known to act as a strong antioxidant that may have some benefits in people with exercise-induced asthma (EIA) by theoretically reducing oxidative load that accompanies exercise. This has been investigated in two small trials of exercise-induced asthma. The first, involving 20 participants, received a daily dose of 30mg lycopene for one week with the results that 55 percent were protected against EIA. In another study of young athletes (n = 19) with EIA, supplemented with lycopene for one week demonstrated no difference in FEV 1.
Supplemental magnesium for prevention of asthmatic attacks has yet to be extensively investigated. Since magnesium is a common deficiency is asthmatics and correlates well with airway hyperresponsiveness, it is worth investigating. One such study, in asthmatic children (n = 37), where half were randomized to receive 300 mg/day magnesium and the others placebo. After two months of supplementation, a methacholine PC20 challenge for bronchial reactivity was significantly diminished in those supplemented with magnesium, but not the placebo group. Other lung parameters (FEV1/FVC ratio) were similar in both groups.
While soy protein, especially genistein, has been known to possess some anti-inflammatory effects, its use in asthma had not been considered until recently. A sub-study of participants in a trial investigating the safely of influenza vaccine in asthmatics (n = 1033) were assessed for their nutrient intake (antioxidant vitamins, soy isoflavones, total fruits and vegetables, fats, and fiber) and severity of condition. The only nutrient that showed any relationship with FEV1 was genistein. Another study looking at nutrient intake and asthma exacerbations included 300 participants who were surveyed for food intake. The participants with the lowest genistein intake had a lower baseline FEV(1) than those with a moderate or high intake. Episodes of poor asthma control were also more common among those with no genistein intake than in those with a moderate or high intake.
Vitamin D deficiency occurs frequently in the general population and can have profound effects on overall health and conditions such as asthma. Vitamin D may play an essential role in pulmonary health by controlling inflammation, regulating T cells, and perhaps as a direct antimicrobial agent. There is strong epidemiological evidence supporting the association between low vitamin D levels and severe asthma. Serum levels of 25(OH)D have been shown to be inversely correlated with severity of asthma, responsiveness to glucocorticoid therapy, and even extent of airway remodeling. Children with asthma, especially, appear to be at risk for vitamin D deficiency., Trials using supplementation are only just beginning, and the optimal serum levels that decreases both risk of development and severity of disease has yet to be elucidated.
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