Does milk increase mucus production?
Introduction
Excessive milk consumption has a long association with increased respiratory tract mucus production and asthma. However while large proportions of the population believe this [1], [2], [3], the published medical evidence documenting these links is limited. People who believe that milk increases mucus production have more respiratory tract symptoms, consume less milk and complain that milk increases throat secretions [1]. Such an association cannot be explained using a conventional allergic paradigm.
Section snippets
‘Conventional’ food allergy mechanisms
Immunologically, allergy is subdivided into four classes. The best known, where there is little dispute is the Type I, or immediate hypersensitivity, reaction due to the presence of IgE antibodies against the offending food. Most of the controversy in food allergy relates to Type III allergic reactions involving food IgG immune complexes. T-cell mediated reactions can also be involved. Cases of asthma-like symptoms resulting from consumption of, or exposure, to dairy foods have only
Milk challenge and asthma
Although several studies have examined the effect of dairy exposure on bronchoconstriction, none have shown any major effect. For instance, Woods et al. found no bronchoconstrictive effects when subjects were exposed to 300 ml of UHT milk compared to a rice milk placebo [4]. Haas et al. exposed patients with asthma or healthy controls to whole milk, skim milk, or water. No differences in expiratory flows were found. However, diffusing capacity did decrease after ingestion of whole milk, but not
Milk exclusion and asthma
In contrast, a number of studies have suggested that the exclusion of milk products from the diet may improve asthma symptoms. In the 1950s, Rowe and Rowe suggested that a variety of foods could contribute to asthma and found that in asthma patients, symptoms often improved on an exclusion diet [7], [8]. With the development of effective medications for asthma treatment these observations were neglected.
Pinnock et al. found that when milk was excluded from the diet, symptoms of cough and nasal
Stimulation of mucus production
The two main mucins produced in the respiratory tract are MUC5AC and MUC5B. In airway tissues from healthy individuals, goblet cells typically express MUC5AC, while glandular mucosal cells typically express MUC5B. MUC5AC and MUC5B are present at lower levels in mucus from normal airways than in sputum from patients with asthma, bronchitis or cystic fibrosis [13]. Similar observations have been made in chronic rhinosinusitis and nasal polyposis [14]. Mucus overproduction is now recognized as a
Proposed mechanism of respiratory tract cells exposure to milk protein
The evidence suggests that some food derivatives can pass into the systemic circulation. In healthy individuals, despite high stomach acidity and enzyme activity in the small intestine, 2% of ingested food is absorbed through the intestines in a form that is sufficiently immunologically intact to produce food allergy [20]. In a variety of situations such as during trauma, larger macromolecules have been shown to enter the portal circulation. Stress and the subsequent release of corticotrophin
Hypothesis
The hypothesis is that A1 milk increases mucus production in the respiratory tract in a sub-population of people who have increased intestinal permeability. Specifically, β-CM-7, acts via μ-opioid receptors on goblet cells, to upregulate MUC5AC gene expression and increases mucus secretion. This would occur only in specifically primed tissues and only when β-CM-7 was able to pass into the systemic circulation.
Evaluation of the hypothesis
Using nasal brushings of normal and asthmatic patients, μ-opioid receptors expression would be examined using western blotting and dual immunofluorescence labelling [19]. To establish whether β-CM-7 modulates mucin production in human respiratory tract mucosa – a respiratory tract mucin secreting goblet cell line would be obtained. β-CM-7 would be added to goblet cell cultures at a range on concentrations. MUC5AC mRNA expression would be assessed at several different time points following
Consequences of the hypothesis
The belief that excessive milk consumption causes excessive mucus production is common, however such an association cannot be explained using a conventional allergic paradigm. Mucus overproduction from MUC5AC glands is characteristic of many respiratory tract diseases [15]. β-CM-7 from A1 milk could potentially increase mucus production from these glands.
This association many not necessarily be simply cause and effect. For this to occur there needs to be a number of prerequisites. The person
Conflict of interest statement
None declared.
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Cited by (25)
β-Casomorphin: A complete health perspective
2021, Food ChemistryCitation Excerpt :Given the fact that BCM modulates cellular metabolism, the influence on allergy signaling was also surveyed. Consumption of milk that can release BCM upon digestion was found to stimulate mucus production from gut MUC5AC glands (Bartley & McGlashan, 2010). In another study, using a human breast-milk sample on the IL-8 secretion in Caco-2 cells demonstrated a three-fold increase in IL-8 secretion in reported allergy milk hydrolysate.
The Allergic Patient
2018, Integrative Medicine: Fourth EditionIntegrative Medicine for Respiratory Conditions: Asthma and Chronic Obstructive Pulmonary Disease
2017, Medical Clinics of North AmericaCitation Excerpt :Certain types of milk (from specific breeds of cow) contain a protein called β-CM-7, which has been shown to stimulate MUC5AC production. It has been hypothesized that milk ingestion may lead to stimulation of respiratory mucin production in the airway and thus increase phlegm production.14 A brief trial (4–6 weeks) of dairy avoidance may be helpful to discern such an association in selected individuals.
The current evidence of integrative approaches to pediatric asthma
2016, Current Problems in Pediatric and Adolescent Health CareCitation Excerpt :Dairy is commonly reduced or eliminated because it is believed that milk increases the production of mucous. Although one study showed improvement in respiratory tract mucus production with milk avoidance, another study showed that dairy and egg consumption may actually decrease wheezing.7,12 Overall, there is insufficient evidence to restrict milk in asthmatic children.13
Dairy Recommendations for Ill Pediatric Patients
2014, Journal of Pediatric NursingThe Allergic Patient
2012, Integrative Medicine, Third Edition