Is Milk and Mucus a Myth?

Is Milk and Mucus a Myth?
3.61 (72.14%) 28 votes

Do dairy products contribute to increased mucus (phlegm) production?


Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

The Dairy Council denies there’s an association between milk and increased mucus production, and they blame it on the Jews. The original myth, they claim, stems from a 12th century Jewish physician. Not just any 12th century Jewish physician, though, but none other than Moses Maimonides himself.

What have we learned in the last 800 years? The latest review on the subject was published last year. Does milk increase mucus production? Is that fact or fiction?

It appears to be fact.

The milk protein casein breaks down in the stomach to produce a substance called casomorphin, which as its name implies, has opioid effects—which makes sense from an evolutionary standpoint, as species survival may depend on a close maternal bond between infant and mother.

The guess is that opioid receptors on the mucus glands in the respiratory tract may respond to the casomorphin from milk, which could potentially “stimulate the production and secretion of mucus from these respiratory glands.” This may explain why “a subgroup of the population who have increased respiratory tract mucus production, find that many of their symptoms, including asthma, improve on a dairy elimination diet.”

Maybe Moses Maimonides was right.

Please consider volunteering to help out on the site.

Image thanks to dkillo and Cali4beach via flickr

Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

The Dairy Council denies there’s an association between milk and increased mucus production, and they blame it on the Jews. The original myth, they claim, stems from a 12th century Jewish physician. Not just any 12th century Jewish physician, though, but none other than Moses Maimonides himself.

What have we learned in the last 800 years? The latest review on the subject was published last year. Does milk increase mucus production? Is that fact or fiction?

It appears to be fact.

The milk protein casein breaks down in the stomach to produce a substance called casomorphin, which as its name implies, has opioid effects—which makes sense from an evolutionary standpoint, as species survival may depend on a close maternal bond between infant and mother.

The guess is that opioid receptors on the mucus glands in the respiratory tract may respond to the casomorphin from milk, which could potentially “stimulate the production and secretion of mucus from these respiratory glands.” This may explain why “a subgroup of the population who have increased respiratory tract mucus production, find that many of their symptoms, including asthma, improve on a dairy elimination diet.”

Maybe Moses Maimonides was right.

Please consider volunteering to help out on the site.

Image thanks to dkillo and Cali4beach via flickr

Doctor's Note

For more on the effects of dairy consumption, check out these recent videos:
Formula for Childhood Obesity
Dairy Estrogen and Male Fertility
Is Milk Good for Our Bones?
Why Do Vegan Women Have 5x Fewer Twins?
Skim Milk and Acne
Preventing Parkinson’s Disease With Diet

Dairy industry policies have also been accused of racial bias, as profiled in this article published in the Journal of the National Medical Association.

For further context, please check out my associated blog post: Vitamin B12: how much, how often?

If you haven’t yet, you can subscribe to my videos for free by clicking here.

58 responses to “Is Milk and Mucus a Myth?

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    1. I can’t begin to thank you enough for posting this video. When explaining this issue as the reason I can’t consume dairy, people tend to think I’m a tad wacky. But seeing it here makes me feel…sane. ♥

  1. Very good information. I was literally asking myself this very same question a couple of days ago, since I had recently heard it mentioned many times.

    Thanks again Dr. Greger. Keep up the great work!

  2. Love, love, love these videos. Proper science with the important bits underlined. The connection between milk and allergies / asthma and mucus / phlegm is well known. Many singers avoid milk for this second reason. And the opiates in milk serve an obvious purpose in mother-child bonding – which begs the question why so many of us drink the breast milk of another species.

  3. I’m a singer, and many singers avoid dairy before a performance because of this. I even heard the director of an elementary school musical warning her cast about this before the show. Go, Maimonides!

  4. “Dairy industry blames Jewish physician” Ha!

    Of course most Jews are in fact lactose intolerant. The Dairy Council must be perturbed at ethnic groups that can not digest their products!

    Good catch Doctor. I think the Dairy Council is in need of some new copywriters.

  5. As someone in a position of trust, you may want to review some of the statements in your video.

    First off, what is it that told you that the source article was a review, was it the title of the journal: “Medical Hypotheses”, or was it the long list of references?

    Secondly, what makes you think that article states that it is indeed fact? There is nowhere in that article that states that this is what happens. Perhaps I missed that part and you can quote it for me so that I can better understand.

    Finally, while you do indeed say that ‘this may affect that’ and ‘this may cause that’, most of this hesitation is invalidated by the fact that you earlier stated that this is certainly what happens since it is a fact.

    That being said, while I have little doubt in my mind that the milk industry is bending facts like every other large industry with rumours or myths or even evidence against them, I abhor when people with presumably noteworthy credentials say things in a way to make the general population think something is true, when it is simply a hypothesis. And so I must apologise for the somewhat hostile tone.

    -a Ph.D. Candidate in Biochemistry, Chemistry, Protein Dynamics, and Drug Design

    1. Thank you so much for your feedback! It’s very sweet of you to take the time to leave a comment. It’s a dream come true to have science-minded folks like yourself reviewing the site and it would be a great favor to me personally and to those visiting the site if you had time to review as many other videos as you can. If you don’t have institutional access to any of the articles I cite please let me know and I can email you PDFs.

      With specific regard to your comments, you’re absolutely right: “review” is only correct in the colloquial sense and not in the technical sense. So I should have said the “latest paper” on the subject instead. In fact I’ll add it to the queue of videos I want to rerecord just to make sure it’s crystal clear. I am indebted to you and all those who have noted site search glitches, videos with sound problems, etc. as I am constantly trying to improve on the site (while at the same time working on coming up with new content every day!).

      The Bartley and McGlashan paper I highlight is indeed more of an explanatory paper, trying to figure out the “why” rather than the “what.” Although reports of mucoid impaction tied to milk allergy go back nearly 30 years, such a large percentage of the population recognizes a milk/mucus link (see for example, here, here, and here) that allergies alone couldn’t account for such a widespread perception. That’s why this new paper is so interesting, offering a non-allergy explanation of why so many people report increased respiratory mucus production with milk consumption. Is their hypothesis (i.e. educated guess) correct? It hasn’t been tested, but hopefully it will lead to a fruitful line of research and I will make sure to keep everyone in the loop.

      And EH, good luck on your thesis!

    2. 1. What is it that told you that what you were reading was a journal? Medical Hypotheses”, or was it the long list of references?

      2. What makes you think that the general population believes something is true based on a hypothesis or because it came from a person with an advanced biochemistry degree?

  6. I appreciate that you responded and are willing to improve and review your descriptions.

    While I cannot access the article titled “Recurrent mucoid impaction in an asthmatic infant with cow’s milk protein allergy”, the article titled “The Milk Mucus Belief: Sensations Associated with the belief and characteristics of believers” states that even in non-believers there was a sensation of needing to swallow, of coating of the throat, etc. They also refer to a similar double blind study they did in which they report that the subjects also experienced the same effect with soy milk, and so conclude that these sensations are just something that comes with this type of drink and is not actually associated with cow’s milk itself.

    The next article titled “Patients’ perceptions of food-induced asthma” found that approximately 35% of respondends reported that dairy products had “made you start to cough, wheeze, feel short of
    breath or get a tight feeling in the chest?”, but with that same questionnaire, about 40% reported those same symptoms with fruits and vegetables. They conclude that ‘confirmation of these perceptions will require well conducted challenge studies’. More importantly here, they say that ‘health professionals need to be aware of their own beliefs.’

    The last study “Do You Believe Milk Makes Mucus?” found that there are equal proportions of people who think milk causes increased mucus production when considering those that have illnesses that could affect that effect (asthma, cystic fibrosis, and allergies). There are also an equal propotion of people that believe it across different ethnicities. The part of this article I personally find interesting is that the stated sources for the idea that milk causes more mucus is 9.8% pediatricians, 18.7% other physicians and 2.6% other healthcare professionals.

    Your argument that allergies alone could not account for such a widespread perception falls under the argumentum ad populum fallacy of argumentation that states that something is true because many people believe it is. Nobody has yet confirmed that milk does indeed cause increased mucus production, and until somebody does so, be it for some small percentage of the population, it is irresponsible to advertise it as being a true effect.

    I do look forward to seeing the results of that study though, being asthmatic myself.

    1. I too read this paper and think Dr. Greger’s video was representative in that all he actually stated was that it “appears to be fact” that milk increases mucus production.

      In fact, Bartley and McGlashan cite a number of studies that support dairy elimination and conclude that “These observations would suggest that in some situations a cow’s milk exclusion diet can be beneficial.”

      To support these observations the authors provided a plausible and testable mechanism to explain why a certain type of milk (A1) could increase mucus production in a subgroup of people who have increased intestinal permeability.

    2. I have to say, whether there’s a study or not, I’ve experienced this. Almost immediately after consuming milk and dairy I begin to have a post nasal drip that leaves me continually coughing and clearing my throat. This was my life every day, it’s very uncomfortable. I then decided to significantly cut back on dairy and make clear choices of when to have it – esp cheese and ice cream. Since I’ve done that I no longer have this post nasal drip and coughing on a daily basis – a new lease on life.

      I must point out that I have allergies and milk isn’t the only food that causes this effect but it was clearly one that did. The Dairy industry reporting that it doesn’t have this effect won’t change my experience and the great results I’ve had from cutting dairy. I do believe there is merit in a hypothesis based on the experience of many – this is the beginning of most theories – actual observation, which we then seek to try to explain. And, regardless of what science says, it’s not common sense to ignore our personal results because the science doesn’t prove it; I think it’s probably more a case of they’ve not YET explained it.

  7. Like I said, most of the wording in the video does indeed have a note of doubt in it, but most people will assume it is just turn of phrase. Scientists will often state things this way because they are aware that discoveries are rarely certain and even more seldom absolute, whereas for the general population, if you tell them it appears that drinking and driving cause accidents, the will take it as a fact because it is something they already think or know to be true.

    When you saw this video, before looking at the sources and reading the comments, were you not under the impression that milk did indeed cause mucus production?

    1. What do you say about singers and their adversion to milk before performing? Were you under the impression that milk caused muscus production? If so, why?

  8. I got this from Dr. Mercola’s site on raw milk. What’s your take on it. (

    Raw Milk is a Healthful, Living Food

    High quality raw milk has a mountain of health benefits that pasteurized milk lacks. For example, raw milk is:

    Loaded with healthy bacteria that are good for your gastrointestinal tract
    Full of more than 60 digestive enzymes, growth factors, and immunoglobulins (antibodies)
    Rich in conjugated linoleic acid (CLA), which fights cancer
    Rich in beneficial raw fats, amino acids, and proteins in a highly bioavailable form, all 100 percent digestible
    Loaded with vitamins (A, B, C, D, E, and K) in highly bioavailable forms, and a very balanced blend of minerals (calcium, magnesium, phosphorus, iron) whose absorption is enhanced by live lactobacilli
    It is not uncommon for people who drink raw milk to experience improvement or complete resolution of troubling health issues—everything from allergies to digestive problems to eczema. It is also common for people who have “milk allergies” to tolerate raw milk just fine. Pasteurized milk is a completely different story.

    Pasteurization Creates a Dead, White Liquid That is NOT Beneficial to Your Health

    Pasteurization turns milk into a dead white liquid whose health benefits are largely destroyed. Consider what pasteurization does to milk:

    The price of killing the pathogenic bacteria is that you also kill the good bacteria which helps digest milk and make it such a nourishing food
    Proteins and enzymes are completely destroyed or denatured, made less digestible and less usable by your body
    Immunoglobulins, metal-binding proteins, vitamin-binding proteins, carrier proteins, growth factors, and anti-microbial peptides such as Lactoferrin are destroyed
    Many vitamins and minerals are rendered biologically unusable
    Fats are damaged and destabilized
    Additionally, the bacteria killed by pasteurization are not removed, so their dead carcasses remain in the milk to ignite immune reactions in those who ingest them, which is one major cause of milk allergies. It isn’t really an allergy to the milk itself, but to the organic cell fragments it contains.

  9. Interestingly, Maimonides was right on alot of medical issues.  I believe he also  wrote that people needed to allow a sufficient amount of green space around cities for clean and, thus promoting optimal health.

    A reviewer on, commenting on one of the English translations of Maimonides medical writings said this:

    Maimonides studied medicine long before he decided to enter the
    profession because he knew that good heath is important to a satisfying
    life. He taught that prevention of illness and the maintenance of good
    health is the major goal of physicians and non-physicians alike. He
    focused his attention not only on the body, but also on the mind, the
    environment, a proper attitude, good interrelationships, the avoidance
    of stress, and other similar subjects.

    Maimonides was very modern in
    his approach to good heath by stressing exercise, proper foods,
    sufficient sleep, and recognizing that nature by itself, without the aid
    of a physician, can resolve many illnesses. His advice on health,
    contained in his medical, philosophical and legal writings, remains
    worthwhile reading today.

  10. I have a germophobic housemate of Jewish descent who is constantly hawking up phlegm and loudly blowing his nose. He thinks it’s just “allergies” but he eats meat, cheese, and dairy pretty regularly. His solution is to gargle Listerine, which I think is probably making things worse for him. Recent studies have found helpful viruses living in human mucous, and most of the bacteria we carry are beneficial as well. But he’s one of those kooky old dudes who will never be deep enough to change his habits, so he’s never tried eschewing meat and dairy to see how it might affect his health. Instead he baselessly insists it’s nothing to do with diet, and he just keeps on suffering and being a noisy annoyance to his housemates. What to do??

  11. That video really helped me a lot, because I’ve been very discouraged lately. I’m a singer in a band, and also I make my own music as a kind of solo project, and I noticed a few years ago I got sick and had all this phlegm and I thought well I just never got rid of the mucus, I never recovered in that aspect. But I also noticed..I drink sometimes 3 to 4 glasses of milk a day. That’s a lot..and it seems that my phlegm buildup is even more increased. I can barely talk and sing now. So I think eliminating milk although I love it so much would be healthy and improve my well being and vocal abilities. I hope.

  12. I have only recently excluded virtually all animal foods. My breathing feels easier, yet another unexpected benefit. Thank you Dr Greger for this material.

    1. JR: I had a conversation just this last weekend with a group of vegans who were all sharing various “unexpected benefits” after switching to their vegan diets. It is fascinating how many medical problems get cleaned up when people start eating healthy – sometimes problems they weren’t even really aware of beforehand.

      Congrats on your easier breathing.

      1. Right On! that’s the bottom line. I’ve experienced the same. When I asked the “Dr.’s” for help 20 years ago, with my constant sinus inflammation and congestion in my nose throat etc, their only solution was drugs and/or surgery-no mention of the power of plants alone! THANK GOD I was willing to eventually change. After all, the definition of insanity is o continue to do the same thing and expect a different result!

  13. Speaking totally subjectively here. I drink close to a gallon of milk a day.. I have no excess mucous or phlegm or any other noticable symptoms. I have done without for months at a time and just miss drinking it. No science, just satisfaction.

    1. While you may show no symptoms of mucous of phlegm, there are also a litany of less symptomatic side effects. The video linked below specifically looks at prostate cancer growth when looking at almond and organic cow milk. Major concerns are also found in IGF-1 regulation with cow milk and we should evaluate our own personal health through multiple factors beyond noticeable symptoms.

  14. Chronic sinus suffer here, I found I was allergic to salycaletes, hence I would get a head cold after a night out. If I went to a more adventurous restaurant I would have severe headaches lasting up to 4 days. I had turbinate surgery. The worst decision of my life. I now have a constant post-nasal drip.

    The best things I have found work for me are:-
    1. swimming in salt water (best in the surf), to clear out my head of mucus.
    2. starting the day with fresh lemon juice, waiting 10 minutes, to then have green tea, inhaling the steam to help clear move the mucus and clear as much as possible, then having a healthy breakfast.

    I have always wondered about milk and mucus. I was told by GPs it was only in children it produced mucus, but tend to err on the side of caution personally.

    Oddly enough Coriander is my number 1 mucus maker. Have that in a meal and I have sneezed 10 times in half an hour on my way to a headache in an hour and migraine like pain in 4 hours. Makes food selection at a lot of restaurants a challenge!

  15. Thank you for sharing this video. It’s very helpful. You might enjoy this page.

    * if you search the paper for the word – cow – then look at the 3rd and 4th finding… it supports what you’re saying I believe.

    I would think raw milk might be an okay option for many. However Dr. Mercola has shared that there are two types of cows and one type has the kind of milk that can cause allergy. They’re called A1 and A2.

    I like how helps people find raw milk sources.

    Blessings! Ali in IL < We support Israel!

  16. Why is everything blamed on the Jews? Sheesh. Anglo Saxon white men have been in power for thousands of years, yet they are always touted for their discoveries and successes, never the war and indignities they’ve committed on humankind.

  17. I am 80 years old and spent 78 years suffering from post-nasal drip and throat congestion. I was constantly spitting to clear my throat. That stopped when I quit drinking three glasses of milk every day. I need no other test or proof.

  18. I am concerned about my sons ongoing problem with excessive mucous – he is well in every way, but has to regularly clear his nose of mucous – especially last thing at night & first thing in the morning.I would like to eliminate milk from his diet, which will be difficult because he loves it, has it with cereal every morning and drinks it every night before bed.If the excessive mucous is being caused by milk, how long would it take to notice any improvement if we completely omit milk from his diet?

      1. Thank you for the suggestion of Almond breeze almond milk.However, due to the fact that I live in Turkey, it is not possible for me to get hold of any kind of milk substitute.(It is also not possible to find tofu, quinoa, soya products etc.)I am currently following a 98% vegan diet -as a result of the revelations I have learned from this wonderful website.I would like to cut out dairy produce from my son’s diet gradually.He is eleven years old – and agrees to try going without milk for one month.Would 1 month be long enough to see improvement with regard to mucous production??
        With regard to calcium, I aim to meet his body’s needs for calcium by including lots of fresh vegetables in his diet, plus flax seeds, tahini and nuts.

        1. A month will be long enough to notice any mucous drop indeed. You can also attempt to make your own almond milk. From my understanding its quite easy, and you need a cheese cloth to strain them after blending the almonds. I would look online for a recipe.

        2. I would agree with Toxins that a month trial will allow you to see if there is benefit to the mucous problem. I would second his comment that there are many other reasons to stop or minimize dairy consumption. Calcium intake will be met by a whole food plant diet. I and I imagine others would be interested in how your trial goes. Good luck.

        3. Debre: What a bummer that you can’t easily buy foods like almond milk and quinoa, etc. I feel for you.

          I wanted to second Toxin’s suggestion of creating your own nut milks. It can be a lot of fun to make your own and while not as convenient, end up tasting a lot better than the store bought brands. If you have some nuts and a blender, it is easy to make any sort of nut milk – or even oat milk if you can get a hold of whole oat groats.

          For the filtering step: I have made nut milks using both a nut milk bag and just a common, small holed colandar. It just depends how picking you are about texture and how good the blender is/how small it chops up the nut bits.

          I have also made nut milks from nut butters (like say almond butter) instead of the whole nuts. Using a nut butter can make the process more convenient since you can avoid the filtering step all together. You just blend up a bit of nut butter with water – perhaps with a touch of sweetener and/or vanilla if relevant (such as for putting on cold cereal). A ratio you might try is: 1/4 cup nut butter to 4 cups water.

          It is a good testament to both you and your son that your son is willing to go a whole month without a food that he loves. I wish you both luck!

  19. This thing about the opiates in milk making dairy addictive, seems to me if you turn that around it explains why some substances are ‘opiates’ in the first place, they trigger mechanisms we’re evolved to have.

  20. Thanks for the video Mr. Michael. About non-diary milk products? Does non diary milk product as; hemp, almond, oat,cashew, coconut milk cause or can cause mucus? Thanks Dr.

  21. NCBI says:
    In the first of three studies investigating the widely held belief that “milk produces mucus,” 60 volunteers were challenged with rhinovirus-2, and daily respiratory symptoms and milk and dairy product intake records were kept over a 10-day period. Nasal secretion weights were obtained by weighing tissues collected and sealed immediately after use. Information was obtained on 51 subjects, yielding 510 person-days of observation. Subjects consumed zero to 11 glasses of milk per day (mean, 2.7; SE, 0.08), and secretion weights ranged from zero to 30.4 g/day (mean, 1.1; SE, 0.1). In response to an initial questionnaire, 27.5% reported the practice of reducing intake of milk or dairy products with a cold or named milk or dairy products as bad for colds. Of the latter group, 80% stated the reason as “producing more mucus/phlegm.” Milk and dairy product intake was not associated with an increase in upper or lower respiratory tract symptoms of congestion or nasal secretion weight. A trend was observed for cough, when present, to be loose with increasing milk and dairy product intake; however, this effect was not statistically significant at the 5% level. Those who believe “milk makes mucus” or reduce milk intake with colds reported significantly more cough and congestion symptoms, but they did not produce higher levels of nasal secretions. We conclude that no statistically significant overall association can be detected between milk and dairy product intake and symptoms of mucus production in healthy adults, either asymptomatic or symptomatic, with rhinovirus infection.

  22. I don’t need to have a PHD to know the answer to this study because I live it. YES, milk and or dairy products causes increase in mucus. I get mucus build up EVERY time I eat anything dairy, like cheese, ice cream, yogurt or milk. I recently started drinking almond milk and stopped eating ice cream because I was always blowing my nose or coughing up mucus and I wasn’t sick. I assumed it was the ice cream so when I stopped eating it the mucus build up stopped. I started eating yogurt thinking it’s not worse than ice cream then I was backed up with mucus again. And it did the same with cheese. That’s when I was certain it was the dairy. I have a no dairy diet and no more mucus build up. To say it doesn’t cause mucus increase is a coverup.

    1. Gene K: The nice thing is that there are nondairy alternatives for all of those things. Try some cashew, almond or coconut based ice cream. You will not be disappointed!

  23. Good day Michael and team! I have a question. I don’t drink milk, but i do drink matzoon which is armenian version of kefir or other type of fermented milk. Online it says that it is safe to drink it because its not milk but the fermented version of it. So my question is – does casein disappear once it transferred into a different bacteria like kefir or matzoon. Here’ s a link what it is and how to make it to understand better what i mean. Thank you so much for everything you do in this world, this blog and for every and each of us! And it was awesome to listen you speak during Vegetarian food fest in NYC!!! Thank you for my signed book!

  24. I had sinusitis, and being very busy with my nose, I gave up cooking and just grabbed large amounts of Camembert cheese for dinner.
    Next morning, the amount of mucus that my nose was producing made me think about the milk-mucus relation…and I like milk !

  25. I changed my diet to a wfpbno diet over two years ago…but continue to suffer from a lot of mucus production. I am continually having to clear my throat and blow my nose especially after meals. If I don’t eat any animal proteins anymore, what could be causing this? Do I have a food allergy to something else?

  26. Hi Colleen,

    I am a volunteer for Dr. Greger. Thank you so much for your question.

    I am not aware of any research that suggests that any particular foods or food groups, aside from dairy, increase mucous production.

    However, you could begin a type of an elimination diet to see what it is that might specifically be causing the issue. You could start by eliminating 2-3 things from the diet, and seeing if you notice the symptoms disappear. If they do disappear, you know it is at least one of the 2-3 foods you eliminated. If the symptoms continue, you can add the 2-3 initial eliminated foods back into the diet, and choose another 2-3 foods to experiment with.

    I apologize that I cannot give any other specific information regarding your question, but I just am not aware of any alternative explanations or solutions.

    Best of luck!

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