Does milk cause mucus?

Many patients note that dairy products, milk in particular, causes increased mucus or phlegm production.  But does milk actually do this?.  Even if it does, it is not an allergic reaction to the milk.  It is important to remember that an allergic reaction to a food is defined as an immune reaction to that food.  If it is not an immune reaction, it is not an allergy.

Several allergists have been having an interesting discussion about this on Twitter over the last day or so:


Dr. David Fischer‏ @IgECPD4
Dr. John Weiner @AllergyNet
Dr. Ves Dimov @Allergy
Dr. Anne Ellis @DrAnneEllis
Dr. Nathan Hare @AllergyTalk (me)

From the published articles in the medical literature, so far, the consensus is that milk does not actually produce an increase in phlegm / mucus.  One intriguing study suggests a hypothesis for why a certain portion of the population could have a problem with milk.

David Fischer, MD ‏ @IgECPD4

Cow Milk vs Soy Milk re: Mucus production:  No Difference

Any perceived increase in symptoms from milk "can be duplicated by a non-cow's milk drink with similar sensory characteristics"

Dr. John Weiner ‏ @AllergyNet

Do dairy products induce bronchoconstriction in adults with asthma?:  No

This is a study for which Dr. Weiner was an author.

"For both FEV1 and PEF there were no statistically significantly differences in group means between active challenge and placebo challenge, between sequence of administration, or between perceptions"

Dr. Nathan Hare (me) @AllergyTalk

Can Fam Phys: Brief discussion, no new data: Conclusion: not enough evidence to say that milk causes increased mucus production.

Association of consumption of products containing milk fat with reduced asthma risk in pre-school children: the PIAMA birth cohort study.: Does not directly answer the question about milk and mucus, but interestingly children consuming more milk fat had decreased risk for asthma

Ves Dimov MD @Allergy

Does milk increase mucus production?: Maybe, for a certain subset of the population - this is only a hypothesis though - no data

1.  beta-casomorphin-7 (beta-CM-7), an exorphin derived from the breakdown of A1 milk, stimulates mucus production in the human colon MUC5AC glands

2. Respiratory tract MUC5AC glands also have mucus overproduction in many respiratory diseases

Hypothesis:

beta-CM-7 in the blood stream from A1 milk after ingestion could cause mucus overproduction in the respiratory tract, leading to symptoms

New York Times 2010 article discusses the issue: Conclusion - no evidence to support that milk causes mucus, or phlegm.