Toolbox Genomics - Food & Lifestyle for Your DNA

Published on Aug. 24, 2017

Dairy, Friend or Foe?

Not all dairy is as bad as you think. 

Lactose intolerance.  You are probably familiar with this term from the friend who declines pizza.  Or perhaps the friend who has a downcast look when she realizes she forgot to bring her LactAid with her after just eating ice cream.

Lactose intolerance, also called lactase deficiency, means that your body is unable to fully digest or breakdown the milk sugar, lactose. People who are lactose intolerant generally do not produce enough of the enzyme lactase, which is specifically needed to break down lactose. Symptoms of lactose intolerance include diarrhea, loose stool, gas, bloating, nausea, and sometimes vomiting, stuffy or runny nose, or increased breakouts.

Ways to determine if you are lactose intolerant:

  1. Eliminate dairy.
  2. Allergy testing. Unfortunately, this is not always accurate. For example, when I personally tested for milk allergies, my results showed that I only had a mild sensitivity. If I eat a dairy containing food, I usually don’t have a reaction as long as it is just once a day.  If I eat multiple dairy containing foods, I find I will breakout and my nose will begin to run. I would not classify my reaction to dairy as mild.
  3. Genetic testing. See if you carry the genes for lactose intolerance.

But what about the French and the Italians?  They eat a lot of dairy and pizza without any problems. Frankly that is a loaded question with many caveats, but there is some new research discussing the different types of milk, specifically the difference between A1 and A2 beta – casein.

First some definitions:

Beta casein: A milk protein that makes up 30% of total milk protein.

  • A1 beta casein:
    • From cows that came from Northern Europe, e.g. Holstein.
    • About 5000-10,000 years ago, there was 1 amino acid change along the A1 gene that created the A1 beta casein from the original A2 beta casein
  • A2 beta casein:
    • The original form of milk that comes primarily from cows from Southern Europe, including the Jersey cow.

BCM-7: bioactive opioid peptide beta casomorphin-7. Now that is a mouthful!  This protein binds to certain opioid receptors in the gastrointestinal (GI) tract.  You may be rather shocked right now: opioid receptors, in your body?  Yes!  This is how pain medications work. The medication binds (attaches) to the receptors and sends a signal to the brain to stop sending out messages of pain. One of the side effects of opioid pain medications is constipation or decreased GI transit time (a fancy way of saying you may not be having regular daily bowel movements). Now let’s find out what happens at this opioid when you eat/drink dairy.

Researchers have found that when you drink milk, digestive enzymes (lactase) break down either A1 or A2 casein (the milk proteins), which cause BCM-7 (our opiod protein) to be released.  However, A2 dairy seems to cause less BCM-7 to be released.  By releasing less BCM-7, there is less binding occurring at opioid receptors.  This may explain why people feel less abdominal side effects when they eat or drink A2 dairy.

A recent study from 2014 looked at how A1 and A2 beta casein affected the GI tracts of men and women. They found that people who drank milk with A1 casein had increased abdominal pain, possibly from constipation or diarrhea and an increase in GI inflammation markers. In contrast, people who consumed A2 milk, had less abdominal pain, firmer stools and less bloating.  Interestingly, women had more symptoms from the A1 milk than men.

Dairy from A2 milk seems to cause less inflammation, less constipation and less diarrhea than milk from A1 cows. If you are looking to obtain milk products from A2 milk sources, look for dairy from A2 cows including Jersey, Guernsey or Normande

In the meantime, if you are interested in knowing if you have the Lactose Intolerance Gene(s), check out your Health Action Report at

Want to learn more? Check out our blog posts here.

The Research:

Comparative effects of A1 versus A2 beta-casein on gastrointestinal measures: a blinded randomised cross-over pilot study.



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