Blog Topics:
1. Dairy introduction
2. Common Dairy Sources
3. What is beta-casein?
4. What's the difference between A1 and A2 beta casein?
5. Effects of Beta-casomorphin 7 (BCM-7)
6. Studies comparing the effects of A1 and A2 beta-casein.
7. Lactose intolerance?
8. Where do you find A1 and A2 beta casein?
9. What should I buy?
10. Conclusion
1. Dairy Introduction
Here’s a cheesy one for ya! Let’s talk dairy lol. I'll start out by saying that not all dairy is equal. You'll see why in a bit. Regardless, it is common practice for a lot of people to cut dairy out on an elimination diet, for helping GI symptoms, or for dermatologic reasons. Regardless, this post isn’t about lactose or lactose intolerance, it’s about the beta-casein proteins in the dairy milk and how they may be affecting your health including digestive discomfort, gut function, cognition, and inflammation!
2. Common Dairy Sources
Let's start out by identifying common dairy sources. Dairy includes cheese, milk, yogurt, sour cream, cream cheese, butter, cottage cheese, heavy whipping cream, and I'm sure there may be more that I'm missing!
3. What is beta-casein?
Now, what's the deal with this "beta-casein" word that I mentioned earlier. Beta-casein is a protein found in cow's milk. It's really that simple. Beta-casein has two primary variants or types: A1 and A2. So, any time that we ingest a dairy product listed above, it is likely that we are taking in either the A1 beta-casein, the A2 beta-casein, or a combination of both.
4. What's the difference between A1 and A2 beta casein?
When we eat dairy that contains beta-casein, it gets digested, just like most things that we eat. The difference between A1 and A2 beta-casein is what happens when they get digested. A1 and A2 have a different protein structure, and because of this, they get broken down differently. The A1 beta-casein protein has an amino acid in its protein strand that essentially allows the tail of the A1 beta-casein protein to get chopped off! This little tail is 7 amino acids long, and we call this molecule Beta-casomorphin-7 (BCM-7). On the other hand, A2 beta-casein protein does not have this same amino acid that allows the chopping to happen, so Beta-casomorphin-7 (BCM-7) is not formed! That's the difference folks, you're a dairy master! (2)
Okay, we're going to keep milking this blog for all its worth! (pun intended lol!)
5. Effects of Beta-casomorphin 7 (BCM-7)
Let's recap. You've eaten dairy from a cow that produces A1 beta-casein, it got digested into Beta-casomorphin (BCM-7) that you have swimming through your body. What's the matter with that?
It turns out, an inreased A1 beta-casein consumption and thus production of BCM-7 is thought to play a role in the development of several diseases. A1 beta-casein consumption is associated with higher mortality from ischemic heart disease. On the other hand, populations who consume more A2 beta-casein have lower rates of cardiovascular disease and type 1 diabetes. Other conditions associated with an elevated BCM-7 (from A1 beta-casein ingestion) include autism and schizophrenia. (1)
Now, those are correlative links, and a variety of factors go into the development of many of these metabolic diseases. However, BCM-7 is also thought to be responsible for disorders including gastrointestinal dysfunction and inflammation which we will dive into in the next section. In this section, 1 and A2 beta-casein are put head to head and markers of inflammation, gut transit time, cognitive function, and other markers are measured in subjects. Read on!
6. Studies comparing the effects of A1 and A2 beta-casein.
In a study, subjects who consumed both types of beta-casein (A1 and A2) for 14 days demonstrated significantly higher post-dairy digestive discomfort, elevated inflammatory biomarkers, higher concentrations of beta-casomorphin 7 (BCM-7), longer intestinal transit times (slower elimination of waste through feces), lower amounts of short chain fatty acids (SCFAs) which are produced by the gut flora and are anti-inflammatory, and an increased response time and error rate on a cognitive test called the "Subtle Cognitive Impairment Test" (SCIT) than subjects who only consumed A2 beta-casein. (2)
To make things simple, these people were more inflamed, had worse bowel function, their microbes weren't as happy, and they weren't as mentally sharp as those who didn't drink the A1 beta-casein dairy products.
Subjects who consumed A2 beta-casein did not demonstrate worsened post-dairy digestive discomfort compared to the baseline in both lactose tolerant and lactose intolerant subjects! (2)
Let's look at another study quickly. A mouse model study gave mice a milk diet containing A1 or A2 beta-casein. It was observed that the groups consuming A1 beta-casein variants had significantly elevated levels of MPO, MCP-1, IL-4, total IgE, IgG, IgG1, IgG2a and leukocyte infiltration within the intestine which are markers of the inflammatory/immune response. All of of this to say that their guts weren't happy and they were showing signs of inflammation! It is also worth noting that this immune response is mediated through the Th2 pathway, the same pathway associated with asthma and eczema. (2,3)
7. Lactose Intolerance?
Allow me to bring up lactose intolerance here. Many people avoid dairy because it has them running to the bathroom and their bowels are a wreck! There is evidence in the study above that those who consumed the A1 and A2 together had longer gastrointestinal transit times, softer stools, and more diarrhea than those who just consumed the A2 beta-casein protein. Essentially, if you experience GI symptoms after dairy consumption, it might actually be the A1 beta-casein and not the lactose! (2)
8. Where do you find A1 and A2 beta casein?
Enough with the sciency stuff! The next question to tackle is where in the heck do you get A1 or A2? Well, you can get A1 at any local steakhouse… lol! Back on track now.
Most milk on the market contains a blend of A1 and A2 beta-casein. The cows that produce the least A1 and the most A2 include Guernsey, Jersey and Brown Swedish whereas those who contain the most A1 include Red, Aryshire, Red-and-White, and Black-and-white cattle breeds. (1) Although this is good to know, most of us don't know what breed of cow our dairy products are coming from. What we do know is that goat milk, sheep milk, and human milk are 'A2-like" and do not produce BCM-7 like A1 does, meaning the dairy products produced from these sources is likely much less inflammatory. (4)
"You mean goat products are fine?!
"Yep!"
"You've got to be (kid)ding me!" <--- Baby goat pun
9. What should I buy?
Products derived from goat or sheep like goats milk or manchego cheese (from sheep milk which I tried for the first time last week and it was absolutely delicious!!) may be better alternatives over our conventionally raised dairy products from our bovine friends. And mind you, we haven't even talked about the hormones (rbST), antibiotics, or grain diets that our cattle are fed to produce this milk!
You're already thinking that you just can't live without dairy. Milk for strong bones right!? (That's for another blog). Whey protein after a lift? Dairy seems to be a cornerstone of western society. Cheese makes the world better, does it not? So, here's some practical tips for my dairy-loving friends out there.
If you absolutely need milk, try unsweetened almond milk, unsweetened coconut milk, or goat milk! Note the unsweetened. I would personally shy away from soy milk or lactose free milk. When it comes to cheese, goat cheese or sheep cheeses are on the menu. A lesser option would be the dairy free cheeses that you can find in the health section of some grocery stores. Follow Your Heart makes a dairy free cheddar cheese that is made mostly from potato and corn. And, lastly, you could try straight up nutritional yeast! This has a nutty/cheddar flavor to it and you can sprinkle it on whatever you're eating as a cheese substitute. If you are super sensitive to butter, you could always get clarified butter (ghee) that is essentially rendered butter that has less of the milk proteins present. Alternative quality fat sources to replace butter may include avocado oil, olive oil, tallow (from grass fed beef), lard (from naturally raised pigs at your farmers market, I wouldn't touch the stuff on the grocery store shelf), duck fat (epic makes this), bison fat (epic makes this too I believe) and coconut oil. Who knows, maybe a few simple dietary modifications may make a big difference in your gut health!
10. Conclusion
Let's bring it home, folks. Most dairy contains a blend of A1 and A2 beta-casein which is just a protein in the milk. The A1 beta-casein gets digested into a bad actor called BCM-7 which can cause gastrointestinal symptoms, decreased brain function, inflammation, and is associated with some disease processes like ischemic heart disease. We find A1 beta-casein in most of our dairy products that come from cows, but products that come from sheep and goats are in the clear! If you're having GI distress or simply want to take strides to lower the inflammatory burden on your body, considering the removal of A1 beta-casein dairy sources from your diet might be a positive step to take!
1. Kaminski, Stainslaw et al. 2007. Polymorphism of bovine beta-casein and its potential effect on human health. Journal of Applied Genetics. 48(3): 189-198.
2. Jianqin, Sun et al. 2016. Effects of milk containing only A2 beta casein versus milk containing both A1 and A2 beta casein proteins on gastrointestinal physiology, symptoms of discomfort, and cognitive behavior of people with self-reported intolerance to traditional cow's milk. Nutrition Journal. 15: 35.
3. Ul Haq, Mohammad Raies, et al. 2014. Comparative evaluation of cow B-casein variants (A1/A2) consumption on Th2-mediated inflammatory response in mouse gut. European Journal of Nutrition. 53(4): 1039-1049.
4. Pal, Sebely, et al. 2015. Milk Intolerance, Beta-Casein and Lactose. Nutrients. 7: 7285-7297.
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