Asthma

Asthma is a chronic lung condition that affects around 16 million people in the US. It is most common in children under age 10, although people of all ages can be affected. Although asthma is seldom fatal, it is quite serious and is the leading cause of school absenteeism and pediatric hospital admission.

 

Symptoms of Asthma

Asthma is a lung disease characterized by airways obstruction that is reversible (but not completely in some patients), either spontaneously or with treatment; airways inflammation; and increased airways responsiveness to a variety of environmental and emotional stimuli.

Symptoms of asthma include a tightening of the chest, cough, wheezing, shortness of breath and mucus production. However, these symptoms are not always present. They come in episodes set off by various triggers. Some people with asthma experience only mild and infrequent attacks while, for others, these can be frequent and serious, requiring emergency medical treatment.

There are several mechanisms which contribute to the airway narrowing which occurs during an asthma attack. The smooth muscles which surround the airways constrict or spasm, making the airways narrower. Fluid also leaks from the blood vessels, filling the cells that line the airways and causing swelling. If the attack is prolonged, inflammatory cells from the bloodstream also leak out with the fluid. The airways are lined with hair-like projections known as cilia, and a thin layer of mucus. In an asthma attack, too much mucus is produced and the cilia cannot move it. Sometimes air becomes trapped in the mucus which blocks parts of the airway.

 

Causes of Asthma

The tendency to have extra irritable airways may have an inherited component, or may be acquired. The early onset of asthma is sometimes triggered by a child not being breastfed. Allergies are a common trigger of asthma, including those to pollen, mold, house dust, animal dander, certain foods and medicines. However, allergies alone will not cause asthma as not all allergic people have asthma and not all asthmatics are allergic. Respiratory infections also aggravate asthma, as can exercise, stress, cigarette smoke, odors, pollution, perfumes and cleaning solutions.

 

Treatment of Asthma

Asthma is a serious disease and can be fatal if left untreated. Most asthma symptoms are controlled with the proper use of various medications, regular medical care and self-monitoring of air flow and symptoms. Even a well controlled asthmatic who is usually symptom-free may experience occasional attacks, often as a result of viral respiratory tract infections.

Corticosteroids are often used to treat chronic asthma. These drugs, which can be inhaled or taken orally, work by decreasing the swelling and inflammation of the airways. Inhaled steroids are more commonly used whereas oral steroids are usually used to treat more severe cases. Side effects of corticosteroid drugs include thinning of bones, ulcers, thin skin, easy bruising and suppression of normal adrenal gland response to stress. In a study published in 1996, researchers at the University of Virginia found that calcium and vitamin D supplements helped prevent the loss of bone mineral density in those taking corticosteroid drugs.1

Bronchodilators, in either oral or inhaled form, are used to treat occasional symptoms of asthma. These drugs work to open up the airways, easing breathing. Oral bronchodilators are rarely used because they can cause side effects such as restlessness, insomnia, headache, loss of appetite, increased heart rate, dizziness, nausea, and vomiting. Long-term use of theophylline may also be associated with behavioral problems and learning disabilities. The drug seems to lower vitamin B6 levels and supplements may be useful in preventing some of the side effects.2

Asthma which is triggered by allergies to pollen may be treated by immunotherapy. Yoga, relaxation, deep breathing techniques and chest massage are useful for people with asthma, including children. Regular exercise to improve lung function can also be valuable.

 

Diet and Asthma

Food allergies sometimes cause asthma and it is useful to identify trigger foods and avoid them. Common ones include eggs, wheat, even gluten (found in wheat, oats, barley and rye), dairy products, nuts, citrus fruits, seafood, and foods containing additives or food dyes. Wine, beer and preserved fruit, which often contain sulfur dioxide, may also cause allergic reactions. Many asthmatics react to as little as five parts of sulfur dioxide per million. Such preservatives are also used by some restaurants to keep fruits and vegetables at salad bars looking fresh and attractive. Monosodium glutamate (MSG) can also cause problems for some asthmatics and should be avoided. Hidden sources of MSG are often included on food labels as 'hydrolyzed protein', 'autolyzed yeast', 'sodium caseinate', and 'calcium caseinate'. Very cold food and drink and sometimes overeating may also trigger an attack.

Anyone who suffers from asthma should eat a healthy, whole-foods diet based on lean proteins, grains, fruits, and vegetables. Large amounts of saturated and animal fats should be avoided as should dairy products which tend to increase the production of mucus. Recent research suggests that Western diets may be linked to asthmatic and allergic reactions in children.3 Vegan and vegetarian diets have been tried as therapy for asthma and have shown benefit in some people, possibly due to the elimination of allergens and/or altered fatty acid metabolism.

Vitamins, Minerals and Asthma

Antioxidants

There is a lot of evidence to suggest that oxidative stress results in inflammation and tissue damage in the respiratory system, and later in immune damage. Those with low levels of antioxidants in their cells may be at increased risk of developing asthma. Dietary selenium deficiency lowers red blood cell glutathione peroxidase activity and is associated with an increased risk for asthma; and low dietary intakes of vitamins C and E also appear to increase asthma risk. High body iron stores increase free radical production and may elevate asthma risk. Higher intakes of antioxidants may significantly reduce oxidative stress and prevent or minimize the development of asthmatic symptoms.

According to researchers from the University of Washington, antioxidant vitamin supplements may help relieve the symptoms of asthma. The researchers measured the amount of breath expelled by the lungs in 17 asthma sufferers. The subjects took peak flow lung function tests while running on a treadmill and breathing in high levels of polluted air. In those asthmatics whose diets were supplemented with daily doses of 400 IU of vitamin E and 500 mg of vitamin C, an 18 per cent increase in peak flow capacity was seen.

Vitamin E

Some research suggests that vitamin E may have a protective effect against asthma. In a study reported in 1995, researchers evaluated the links between diet and asthma over a ten-year period in 77,866 women aged from 34 to 68. Women with the highest vitamin E intakes had around half the risk of asthma compared to those with the lowest intakes.4

In a 1995 study, vitamin E supplements were added to the treatment regime of asthmatics, and increases in levels and activity of white blood cells was seen, suggesting improvements in the effectiveness of the immune system.5

Vitamin C

Low vitamin C intake may be linked to the incidence of asthma. Epidemiological studies show associations between oxidant exposure, respiratory infections, and asthma in children of smokers. There is also evidence that oxidants produced in the body by overactive inflammatory cells contribute to ongoing asthma. Vitamin C is the major antioxidant substance present in the airway surface liquid of the lung, where it could be important in protecting against both damage from toxic chemicals and free radicals which may worsen the symptoms of asthma.6 Low vitamin C levels are associated with increased bronchial reactivity.7

Symptoms of asthma in adults appear to be increased by exposure to environmental oxidants and may be decreased by vitamin C supplementation; although not all studies show positive results. Vitamin C has been shown to improve lung function, white blood cell function and motility, and to decrease respiratory infections and hypersensitivity reactions by reducing histamine levels. Most of the studies conducted so far have been short term and have assessed the immediate effects of vitamin C supplementation. The effect of long-term supplementation with vitamin C is unclear.8

In a 1997 double blind study, 20 asthma patients underwent lung function tests at rest, before, and one hour after receiving 2 g of oral vitamin C. The study involved a seven-minute exercise session on a treadmill and lung function tests were performed after an eight-minute rest. This procedure was repeated one week later, with each patient receiving the alternative medication. In nine patients, a protective effect on exercise-induced hyper-reactive airways was seen.9

B Vitamins

Increased intake of vitamin B6 may reduce the symptoms of asthma in some sufferers, particularly children. A study done in the 1970s looked at the effect of five months of pyridoxine therapy (200 mg daily) in asthmatic children and found significant improvement in symptoms and decreased need for anti-asthma medications such as bronchodilators and cortisone.10 Researchers involved in a 1985 study found a dramatic decrease in frequency and severity of wheezing or asthmatic attacks in those taking vitamin B6 supplements.11 However, not all studies have found beneficial effects.12

Vitamin B12 therapy may also be of value in childhood asthma. Some studies have shown benefits with vitamin B12 injections, particularly in those who are sensitive to sulfites.

Magnesium

Magnesium appears to play an important role in lung function as it relaxes bronchial smooth muscle. This dilates airways and reduces the effects of inflammation. It may also affect the function of immune cells which release inflammatory chemicals. Intravenous infusion of magnesium sulfate has been used to treat asthma attacks and produces a rapid widening of the airways,13 and magnesium sulfate aerosols have also been used effectively.14 Magnesium sulfate administration has also been used to enhance the effect of bronchodilator drugs. Many drugs used in the treatment of asthma cause a loss of magnesium.

As well as being used to treat acute asthma, magnesium may be useful in the prevention of the disease as some research has shown that low dietary magnesium intake is linked with impaired lung function and asthma. In a 1994 study of 2633 adults aged from 18 to 70, UK researchers found that high dietary magnesium intake was associated with a significantly better lung function and a reduction in lung hyper-reactivity.15

In a 1997 double-blind, placebo-controlled study, 17 asthmatics were fed a low magnesium diet for two periods of three weeks, preceded and separated by a one week run-in/wash-out, in which they took either placebo or 400 mg magnesium per day. Asthma symptom scores were significantly lower during the magnesium treatment period.16 Intravenous magnesium has been successfully used as an emergency treatment for asthma in children

Selenium

As an antioxidant, selenium acts to protect cells against oxidative stress. It is an essential component of the enzyme glutathione peroxidase, which reduces hydrogen peroxide and other organic peroxides to harmless substances. By detoxifying peroxides, glutathione peroxidase helps to stabilize cell membranes. Inflammatory cells in asthmatic airways produce oxygen-derived free radicals and peroxides which damage lung tissue and enzymes. Selenium may be able to protect against this damage.

In a study done in 1994 in New Zealand, researchers surveyed 708 children and found symptoms of wheezing in just over 20 per cent. For 26 of the children with current wheezing and for 61 healthy children, researchers measured selenium levels in blood samples which had been taken eight years earlier. The results showed that wheezing was more common in those with low levels of selenium, suggesting a possible link. However, current serum levels were not measured.17 Other studies have shown reduced selenium concentrations in adults. Researchers involved in another New Zealand study done in 1990, found that whole blood selenium concentrations and glutathione peroxidase activity were lower in adults with asthma than in those without.18

ÿ 1993 study, Swedish researchers conducted a study of 24 adults with asthma in which half of the patients received 100 mcg of selenium per day for 14 weeks, while the other half received a placebo. Six patients from the selenium-supplemented group and one from the placebo group noticed significant clinical improvement, although neither group showed improvement in laboratory measures.19

Sodium

Some research reports suggest that high dietary sodium intake contributes to asthma and airway hyper-reactivity. A 1993 UK study tested the effects of either a placebo or sodium supplements on asthma sufferers who had previously followed a low sodium diet. The results showed a worsening of symptoms and laboratory measurements of disease severity in those patients on the high sodium diets.20

Other Nutrients

Essential Fatty Acids

Low intakes of omega-3 fatty acids may contribute to the occurrence of asthma. The ratio of omega-3 to omega-6 fatty acids has been shown to be low in asthma sufferers.21 Supplements may be useful in relieving symptoms in some asthmatics, although not all studies have shown beneficial effects.22

Herbal Medicine and Asthma

Herbal treatment of asthma involves the use of anti-catarrhal and expectorant remedies to ensure that there is the minimum build-up of sputum in the lungs. Other herbs can be used to soothe and support the use of expectorants. Anti-spasmodic plants ease the spasm response in the muscles of the lungs and anti-microbials are useful in preventing secondary infections. Herbs which calm the nervous system are useful to alleviate the stress-related aspects of asthma.

Herbs which have been used to treat asthma include elecampane (Inula helenium), mullein (Verbascum thapsus), astragalus (Astragalus membranaceous), licorice (Glycyrrhiza glabra), asthma weed (Chamaesyce hirta) and wild cherry (Prunus serotina).

 

 

1 Buckley et al.Calcium and vitamin D3 supplementation prevents bone loss in the spine secondary to low-dose corticosteroids in patients with rheumatoid arthritis. A randomized, double-blind, placebo-controlled trial. Ann Intern Med 1996 Dec 15;125(12):961-968

2 Shimizu T; Maeda S; Arakawa H; Mochizuki H; Tokuyama K; Morikawa A. Relation between theophylline and circulating vitamin levels in children with asthma. Pharmacology, 1996 Dec, 53:6, 384-9

3 Carey OJ; Cookson JB; Britton J; Tattersfield AE The effect of lifestyle on wheeze, atopy, and bronchial hyperreactivity in Asian and white children. Am J Respir Crit Care Med, 1996 Aug, 154:2 Pt 1, 537-40

4 Troisi RJ; Willett WC; Weiss ST; Trichopoulos D; Rosner B; Speizer FE A prospective study of diet and adult-onset asthma. Am J Respir Crit Care Med, 1995 May, 151:5, 1401-8

5 Pletsityi KD; Vasipa SB; Davydova TV; Fomina VG. Vitamin E: immunocorrecting effect in bronchial asthma patients. Vopr Med Khim, 1995 Jul, 41:4, 33-6

6 Hatch GE Asthma, inhaled oxidants, and dietary antioxidants. Am J Clin Nutr, 1995 Mar, 61:3 Suppl, 625S-630S

7 Soutar A; Seaton A; Brown K Bronchial reactivity and dietary antioxidants. Thorax, 1997 Feb, 52:2, 166-70

8 Bielory L; Gandhi R Asthma and vitamin C. Ann Allergy, 1994 Aug, 73:2, 89-96; quiz 96-100

9 Cohen HA; Neuman I; Nahum H Blocking effect of vitamin C in exercise-induced asthma. Vitamin C supplements can also help to reduce exercise induced asthma by reducing airway hyperreactivity. Arch Pediatr Adolesc Med, 1997 Apr, 151:4, 367-70

10 Collipp PJ; Goldzier S 3d; Weiss N; Soleymani Y; Snyder R. Pyridoxine treatment of childhood bronchial asthma. Ann Allergy, 1975 Aug, 35:2, 93-7

11 Reynolds RD; Natta CL. Depressed plasma pyridoxal phosphate concentrations in adult asthmatics. Am J Clin Nutr, 1985 Apr, 41:4, 684-8

12 Sur S; Camara M; Buchmeier A; Morgan S; Nelson HS. Double-blind trial of pyridoxine (vitamin B6) in the treatment of steroid-dependent asthma. Ann Allergy, 1993 Feb, 70:2, 147-52

13 Ciarallo L; Sauer AH; Shannon MW a Intravenous magnesium therapy for moderate to severe pediatric asthma: results of a randomized, placebo-controlled trial. J Pediatr, 1996 Dec, 129:6, 809-14

14 Emelianova AV; Goncharova VA; Sinitsina TM. Magnesium sulfate in management of bronchial asthma. Klin Med (Mosk), 1996, 74:8, 55-8

15 Hill J; Micklewright A; Lewis S; Britton J Investigation of the effect of short-term change in dietary magnesium intake in asthma. Eur Respir J, 1997 Oct, 10:10, 2225-9

16 Britton J et al. Dietary Magnesium, Lung Function, Wheezing, And Airway Hyperreactivity In a Random Adult Population Sample. Lancet. 1994; 344: 357-361.

17 Shaw R, Woodman K, Crane J, Moyes C, Kennedy J, Pearce N. Risk factors for asthma symptoms in Kawerau children. N Z Med J. 1994;107:387-391.

18 Flatt A, Pearce N, Thomson CD, Sears MR, Robinson MF, Beasley R. Reduced selenium in asthmatic subjects in New Zealand. Thorax. 1990;45:95-99

19 Hasselmark L, Malmgren R, Zetterstrom O, Unge G. Selenium supplementation in intrinsic asthma. Allergy. 1993;48:3026.

20 Carey OJ; Locke C; Cookson JB Effect of alterations of dietary sodium on the severity of asthma in men. Thorax, 1993 Jul, 48:7, 714-8

21 Sakai K; Okuyama H; Shimazaki H; Katagiri M; Torii S; Matsushita T; Baba S. Fatty acid compositions of plasma lipids in atopic dermatitis/asthma patients. Arerugi, 1994 Jan, 43:1, 37-43

22 Hodge L et al. Effect of dietary intake of omega-3 and omega-6 fatty acids on severity of asthma in children. Eur Respir J, 1998 Feb, 11:2, 361-5