Asthma

"Symptoms of milk-protein allergy include cough, choking, gasping, nose colds, asthma, sneezing attacks..." [Annals of Allergy, 1951; 9]

Asthma is one of the three manifestations of a pattern of allergy that is called atopy – a genetic tendency to develop allergic diseases.  The other two are eczema and hay fever.  Asthma due to allergy can come from both airborne and food sources.  Patients with delayed pattern food allergy have the most severe and persistent inflammatory form of chronic asthma.

While airborne problems are more obvious to asthmatic sufferers, food problems may be a well-hidden source of lung disease.  Many studies of food allergy involve patients with food-induced asthma.  Eczema and asthma are often associated in atopic patients with food allergy.

In a group of 320 children with atopic dermatitis, 55% had asthma.  Food challenges triggered respiratory symptoms in 59% (rhinitis, laryngeal edema, wheezing, and dyspnea).  Asthma is frequently treated only as an airborne allergy problem or as a problem unrelated to allergic processes and the possible role of food allergy is neglected.  It is overlooked because the usual skin tests are often negative and the history is often not helpful as symptoms appear gradually, hours or days after ingestion of the food.  Milk, wheat, egg, yeast, preservatives, colorings, coffee and cheese are the main foods implicated.

Food allergens may be found in the bloodstream within circulating immune complexes that trigger the release of immune mediators into the bloodstream.  These chemicals cause a variety of symptoms, including constriction of the bronchial smooth muscle in the lungs; this is the first event during an asthmatic attack.  Airflow is reduced in the narrowed tubes.  Air has a harder time leaving the lungs than entering, with the result of prolonged noisy exhalation.  This inflammatory, obstructive phase is the most important mechanism of chronic asthmatic bronchitis.

Respiratory complaints among MCS patients include adult-onset "asthma", shortness of breath, and fibrotic lung disease.

Dietary consumption of apples and selenium intake (assessed by food frequency questionnaire) were each associated with a reduced risk of asthma in an English study of adults. [Am J Respir Crit Care Med 2001;164(10): pp.1823-28]

Children with asthma have been shown to have a metabolic defect in tryptophan metabolism.  Tryptophan is converted to serotonin, a known bronchoconstricting agent in asthmatics.  Studies have shown that patients benefit from either a tryptophan-restricted diet or B6 supplementation to correct the blocked tryptophan metabolism.  Pyridoxine may also be of direct benefit to asthmatic patients, since it is a key cofactor in the synthesis of all the major neurotransmitters.

Being overweight increases the risk of asthma. [Arch Intern Med 1999;159: pp.2582-8]  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. [BMJ 2000;320: pp.827-32]

About half of asthmatic patients also have GERD, of which heartburn is a symptom.  It is not entirely clear, however, whether asthma is a cause or effect of GERD.  Some experts speculate that the coughing and sneezing accompanying asthmatic attacks cause changes in pressure in the chest that can trigger reflux.  Exercise-induced asthma does not appear to be related to GERD.  Certain asthmatic drugs that dilate the airways may relax the LES and contribute to GERD.