Does dairy consumption increase mucus production? — Jamie Lee ...

Does dairy consumption increase mucus production?
Dietetic Intern, Ash Linxwiler, digs into the history and research surrounding dairy and mucus production.
The belief that milk consumption increases mucus production and respiratory congestion has been a theory for many centuries.
Where did this theory come from?
Ancient Chinese medicine theorized a strong connection between milk products and the production of phlegm. It was believed that ingesting milk products would increase phlegm in the respiratory tract. Practitioners also believed this increased production of phlegm created “phlegm nodules” in the joints, breasts and prostate. These “phlegm nodules” are now commonly known as breast/prostate cancer, and arthritis.
This theory continued in 12th century writings of Jewish physician Moses Maimonides. Maimonides discussed when, what and how much of certain items to eat in order to manage asthma symptoms. Dairy was only one of many items he restricted his patients from consuming.
What does the research say?
The most prominent research concerning the link between dairy and mucus comes from researchers in Australia who have been investigating the matter since the late 1980’s.
They first started by simply examining participants response to consuming a set amount of milk. They compared their results with their personal medical history and looked for associations between individuals who stated they experienced greater symptoms. In another trial, patients were exposed to the common cold and their symptoms were meticulously observed. Despite the fact that there was no measured increase in mucous excretion, some patients reported increased feelings of congestion. They continued this work with several other trials looking at how personal beliefs and history of respiratory conditions may also play a role. In each of their studies the team concluded that there is no evidence to show dairy consumption causes an increase in mucous production or increased phlegm symptoms.
Interestingly, they found in each study that participants who believed the myth, reported significantly higher instances of respiratory symptoms compared to non-believing participants, despite there being no physical evidence to support these claims. This consistent finding shows that personal beliefs have a strong effect on perceived experience of increased mucous.
All of this suggests there is no definitive tie that links dairy consumption to mucous production for the population as a whole. That being said, some research supports the possibility that a small set of individuals may be susceptible to increased mucus production due to a very specific protein intolerance.
Cow’s milk contains dozens of different proteins and these specific proteins can vary depending on the breed of cow. One of these proteins, which can be found in some, but not all cow’s milk, is beta-CM-7, an A1 beta casein (protein). This protein is responsible for creating mucous in the gastrointestinal system (please note this is considered a beneficial process in digestion). There is some evidence to suggest that individuals who struggle with increased respiratory inflammation may be triggered to produce excess mucus in the respiratory tract due to this protein. This stimulation of the mucous glands in the respiratory tract could lead to increased asthma and respiratory symptoms and might explain why some individuals with asthma and COPD experience increased relief when they eliminate milk products from their diet.
So What Does This Mean? How Should I approach Milk?
For the majority of the population, milk consumption will not contribute to increased mucus production. There are many reasons someone might remove milk from their diet but the fear that it induces phlegm production may not need to be one of them. *Note, research is often heterogenous, centering white, cis-gendered men as the human research subject. Would this research look different for Asian folx or other subject populations?
It is important to note that milk products, have many beneficial elements. To start, milk products are a strong source of protein, fats, vitamin D and calcium. While calcium can be found in other items such as leafy greens, it is more readily absorbed in milk form and reduces the risk of osteoporotic bone fractures. Contrary to several trendy claims, milk products are a powerful anti-inflammatory factor for the digestive tract thanks to the presence of butyric acid. Additionally, the bacteria found in milk products is extremely beneficial to intestinal flora that is necessary for gut health. Some recent studies have also shown milk can be beneficial in reducing hypertension. For all of these reasons, dairy can play a powerful nutrient role in an individual’s diet.
Consistent with Intuitive Eating practice, deciding whether to consume dairy is a deeply personal decision that can be made by balancing your individual physical and emotional response to the item with your knowledge of possible nutritional benefits. You know your body better than anyone.
*The original version of this blog included language that was not respectful to the historical and current day value of Chinese medicine. I am grateful to Chinese practitioner, Maria “Chris” Hicks, LAc for reaching out following the publication of this article to bring this to my attention. This has allowed me to address my own internalized bias, correct my language and grow as a writer and future practitioner.
Pinnock,C.B., et al. Relationship Between Milk Intake and Mucus Production in Adult Volunteers Challenged with Rhinovirus-2. The American Review of Respiratory Disease. 1990;141(2):352–356. DOI:10.1164/ajrccm/141.2.352