Vitamin and Mineral Treatment in Asthma

by Aminder Singh, BSc, ND (cand. 2015), and Lindsay Feuerstein, BSc, MSc. (cand. 2013)

Introduction

Asthma is one of the world’s most common chronic diseases, which affect the lives of more than 235 million people worldwide.¹ In America alone, 20 million are affected, 4.8 million of them children. Approximately 5500 asthmatics die each year, and most deaths are preventable but represent inadequate treatment.² The current understanding of asthma is that it is a chronic inflammatory disease of the lungs that appears to result from complex interactions among genetic, immunologic and environmental factors.³ It is associated with bronchial hyper-responsiveness to a variety of stimuli and airway inflammation that leads to airway obstruction.⁴ Continued inadequate management can lead to persistent asthma symptoms, including a chronic cough or wheeze, chest tightness, shortness of breath and frequent recurrence of asthma exacerbations, characterized by the life-threatening situation known as “status asthmaticus.” .Asthmatic symptoms are often aggravated by “triggers” such as allergen exposure, including foods or food additives and botanicals; respiratory infections, second hand smoke, perfumes and various chemical agents ⁴.Asthma has no set pattern in terms of the presentation of its symptoms; . fact, symptoms can be mild, moderate or severe; cary from person to person; clare up from time to time and then not appear for long periods;,and cary from one episode to the next,;making this condition quite unpredictable. To add, the cause of asthma remains unknown, and currently there is no identified cure ⁵. Long-term control of persistent asthma symptoms is accomplished by the use of daily anti-inflammatory agents and avoidance of irritants. Anti-inflammatory medications have been shown to reduce symptoms and may help to prevent progression of the disease ².Often doctors cannot determine why someone gets asthma, yet the condition remains t significant cause of morbidity and mortality. Given the high prevalence of asthma and its eafect on individuals, there is a need to identify interventions that can be used to complement conventional asthma therapy and, more importantly, relieve and prevent the reoccurrence of asthmatic symptoms.

Current Influences

As Allan and Devereux (2011) explain, the increase in asthma prevalence is most likely to be a consequence of changing environmental/lifestyle factors rather than of genetic influence.⁶ The primary nonpharmacological intervention for people with asthma should be to focus on identifying the individual’s triggers and the means of eliminating or avoiding them.² Viral infections are the major trigger for the younger asthmatics; therefore, immunization for influenza is highly recommended for these patients and their families.⁷ Decreasing or eliminating irritant or allergen exposure is also a significant means of reducing the risk of triggers. Smoking cessation should be a major concern for discussion if the patient or any member of the patient’s family smokes.² Reducing exposure to known triggers should not be underestimated as a significant treatment plan for individuals with asthma.

Significant advances have been made in the treatment of asthma, largely involving improvements in existing therapies such as the commonly known corticosteroids and β-agonists.⁸ However, relatively recent research suggests that a changing diet has emerged as a promising contributory factor to the decrease in asthma. With that, there have been investigations in regard to the association between diet and asthma, with the potential for dietary interventions to complement conventional asthma treatments.⁶ Specifically, the antioxidants vitamin C, magnesium, and polyunsaturated fatty acids have been a significant focus.

Key Findings

Nutritional Supplementation

It has been suggested that dietary antioxidants can modify the manifestation of symptoms in adults susceptible to asthma.⁹ Inflammation is the main culprit behind asthma symptoms and the target of commonly prescribed asthma medications. Inflammation in the airways increases the risk of oxidative damage, predominately due to the activity of immune cells such as macrophages, neturophil,s and lymphocytes which can release reactive oxygen species (ROS). This in turn further enhances inflammatory responses through the production of pro-inflammatory cytokines.¹⁰ Some studies have found that patients who have received antioxidants as a treatment have been shown to have a reduction in certain asthma symptoms as a result of lower inflammatory responses. For example, Guo et al. (2012) supplemented asthma patients with a multinutrient antioxidant formula for two months, after which it was demonstrated that nutritional supplementation significantly improved micronutrient and oxidative stress status, inflammatory responses, immune function as well as better asthma control.¹⁰ Complementary evidence has shown that dietary fruit intake (high in antioxidants) is significantly associated with a reduced risk of diagnosed asthma. More specifically, when subcategorized, citrus fruits were far more associated with a reduced risk of asthma, primarily due to the exceptionally high levels of vitamin C.⁹ The protective effect of fruit appeared to be related to the potent antioxidant capacity of vitamin C, and was independent of all other nutrients investigated. Murray (2001) confirms that vitamin C is a major antioxidant substance in the airway surface area of the lungs, where it plays an important role in protecting against both endogenous and exogenous-induced oxidative damage.¹¹ Further, high-dose vitamin C (as ascorbic acid) therapy of 1 to 2g/day appears extremely effective based on the increasing exposure of inhaled oxidants in the respiratory system. In addition, vitamin C has shown to help asthmatics by lowering histamine levels.¹¹

Fatty acids are important mediators of allergy and inflammation because of their ability to form inflammatory prostaglandins, thromboxanes, and leukotrienes.¹² Altering dietary intakes can significantly increase or decrease inflammation, depending on the type of fatty acid increased. Flaxseed and fish oil are the most commonly consumed supplements, but food sources such as salmon, mackerel, walnuts, and flax offer substantial levels of the beneficial omega-3 fat to the diet.¹² Barros et al. (2011) demonstrated that higher intakes of omega-3 polyunsaturated fatty acids (PUFAs), alpha-linoleic acid (ALA) were associated with good asthma control, while the risk for uncontrolled asthma increased with a higher omega-6 to omega-3 ratio.¹³ Leukotrienes are recognized as contributors to the inflammatory process of asthma; specifically, leukotriene E4 mediates many of the principle features of asthma, such as bronchial constriction, hyperresponsiveness, and increased vascular permeability.⁷ It is important to measure dietary (PUFA) treatment response based on these outcomes over the course of therapy, which might reflect ongoing improvement in airway function.

In addition, recent evidence has shown that low dietary magnesium (Mg) intake can also have an impact on the occurrence and management of asthma. The average intake of Mg by adults in the US ranges between 143 and 266mg/day, a level well below the RDA.¹¹ Magnesium is critical to many cellular functions and participates in more than 300 enzymatic reactions, but its role in asthma has been attributed to the promotion of relaxation of the bronchial smooth muscles.^12,14 In smooth muscles, magnesium decreases intracellular calcium by blocking its entry and its release from the endoplasmic reticulum and by inhibiting calcium interaction with myosin results in muscle relaxation, dilating airways and facilitating easier breathing.¹⁴ Magnesium is available in several different forms, but absorption has been shown most optimally when bound to citrate or aspartate, although 25 to 75mg/kg doses of intravenous Mg sulfate have been a well proved and clinically acceptable measure to halt acute asthma attacks and acute exacerbations of COPD.^11,14 Due to the chronic inflammatory nature of asthma and a Mg deficiency’s being associated with impaired lung function and increased inflammation, exhaled nitric oxide (NO) and C-reactive protein (CRP) are often measured to assess bronchial and systemic inflammation.¹⁵ Total serum Mg levels are also valuable to assess micronutrient status during and after nutritional treatment.

Research findings herein have been found to be inconclusive among comparable studies. With that, nutritional supplementation has not been fully proved effective, but does not exclude the possibility that a therapeutic diet with adequate nutrient intake ma protect against the development of symptomatic asthma.

Contraindications of Supplementation

Vitamin C is extremely safe in most individuals. Diarrhea and intestinal distension or gas is the most common side complaint associated with supplementation. Vitamin C administration up to 10g/day has not shown any negative physiological effects.¹¹ Magnesium sulfate is generally a generally safe form to administer. Minor side effects may include epigastric or facial warmth, flushing, pain and numbness at the infusion site, dry mouth, and malaise.¹⁴ An excessive intake of dietary Mg is not likely to cause toxicity except in the case of individuals with renal impairment, due to the ability of the kidneys to remove Mg rapidly so that significant serum increases cannot occur.¹²

Recommendations

Asthma therapy is assessed by symptoms, exacerbations, and measure of lung function. These are important as different means of guiding treatment and have shown positive benefits on outcome measures.² Bronchial challenge testing, for example is a measure of airway smooth muscle reactivity that has been used for many years as a diagnostic test for asthma.⁸ Functional assessments such as measurement of PEF or FEV1, with close monitoring of these parameters, provide a useful and objective guide to estimate severity and clinical response to therapy or intervention. A peak flow test measure how fast one can breathe out; it is also known as a peak expiratory flow (PEF). This test is highly recommended to help diagnose asthma, but also to check the response to treatment or to help patients recognize when their asthma condition is worsening. PEF should be monitored regularly to be useful, and is important to use a consistent device to compare values.⁴ More recently, a new diagnostic tool has identified that some asthmatics are unlikely to respond to steroid inhalers. A new “inflammometry” test measures the amount of NO in exhaled air. NO levels help to identify whether the asthma results from eosinophili or neutrophilic airway inflammation.⁴ When NO levels are low, the patient is very unlikely to respond to inhaled steroids. This is a huge breakthrough in determining the most effective form of treatment on an individualized basis. In addition, regular visits to the doctor are highly recommended not only during asthma exacerbation but also because most cases of asthma change over time.

Conclusion

Asthma is complex with a large variety of possible causes and, unlike many other diseases that are mainstream, the death rate is modest with 4000 deaths per year.⁴ Even though most asthmatics do not die as a result of the disease, they spend a large part of their daily lives coping with the symptoms.

Despite the overwhelming prevalence of the asthma and the suffering it causes, relatively incremental progress has been made toward improving treatment, understanding the cause, prevention and finding a cure. Until the complete etiology of asthma is discovered, the general agreement appears to be that nutrition assessment and therapy recommendations include individualized evaluation for environmental triggers; a diet of wholesome foods to provide optimal energy and a balance of nutrients and phytonutrients; careful adherence to medications; frequent monitoring to maintain healthy pulmonary status; and education of the patient, family, and community.

Research results remain inconsistent but encouraging, and food and individual nutrients continue to be studied for possible roles in the etiology or treatment of asthma. Because oxidative stress plays a key role in the progression of the inflammatory response in asthma, it has been proposed that up to 2g/day of antioxidants such as vitamin C may represent an effective strategy in the treatment of the disease. In the same manner, essential fatty acids have shown to be protective and therapeutic against inflammation associated with asthma, when consumed in the correct ratio of omega-6 to omega-3. Finally, in addition to Mg-rich foods such as kelp, nuts, legumes, or whole grains, oral magnesium supplementation up to 280mg/d or injected magnesium sulfate of 25g/day can improve bronchial airflow.

Current asthma therapy is highly effective in the majority of patients. However, patients with acute severe asthma with increased episodes of exacerbations are often poorly controlled on maximal doses of prescribed medical treatments, none of which are disease modifying or curative for asthma. This poses the need for the development of new treatments or adjunctive nutritional therapies for targeting specific physiological processes involved in the pathogenesis of the disease. Therefore, multinutrient supplementation through synergistic effects may more effectively improve the pathological features of asthma.

Notes

1. World Health Organization. Asthma [Web page]. 2010. www.who.int/respiratory/asthma/en. Accessed Oct. 2012.

2. Lung CL. Asthma and COPD: identification and interventions. Case Manager. 1998; 9(3):33–38.

3 . Crowley LV. An Introduction to Human Disease. Sudbury: Jones and Bartlett; 2010.

4 . American Asthma Foundation [website]. www.americanasthmafoundation.org.

5 . Asthma Society of Canada [website]. September 2012. www.asthma.ca

6 . Allan K, Devereux G. Diet and asthma: nutritional implications from prevention to treatment. J Am Diet Assoc. 2011;111:258–268.

7. Szefler SJ. Advances in pediatric asthma in 2009: Gaining control of childhood asthma. J Allergy Clin Immunol. 2012;125;69–78.

8. Caverley PM, Walker P. What’s new in Asthma and COPD. Medicine. 2003;31(8).

9. Patel BD, Welch AA, Bingham SA, et al. Dietary antioxidants and asthma in adults. Thorax. 2006;61:388–393.

10. Guo C-H, Liu P-J, Lin K-P, Chen P-C. Nutritional supplement therapy improves oxidative stress, immune response, pulmonary function, and quality of life in allergic asthma patients: an open-label pilot study. Altern Med Rev. 2012 Mar;17(1):42–56.

11 . Murray MT. Encyclopedia of Nutritional Supplements. New York: Three Rivers Press; 2001.

12 . Gropper SS, Smith J, Groff J. Advanced Nutrition and Human Metabolism. 5th ed. Wadsworth; 2009.

13 . Barros R, Moreira A, Fonseca J, et al. Dietary intake of ɑ-linolenic acid and low ratio of n-6:n-3 PUFA are associated with decreased exhaled NO and improved asthma control. Br J Nutr. 2011 August;106(3):441–450.

14 . Bichara MD, Goldman RD. Magnesium for treatment of asthma. Can Fam Physician. September 2009;55(9):887–889.

15 . Kazaks AG, Uriu-Adams JY, Albertson TE, Shenoy SF, Stern JS. Effect of oral magnesium supplementation on measures of airway resistance and subjective assessment of asthma control and quality of life in men and women with mild to moderate asthma: a randomized placebo controlled trial. J Asthma. 2010;47:83–92.