Dairy is a superfood! It provides a variety of essential vitamins, minerals, and other health-promoting compounds, including calcium, vitamin K2, B vitamins, protein, probiotics that help with gut health, and healthy fats. These include the odd-chain saturated fat pentadecanoic acid (C15:0), which some researchers now consider an “essential” fatty acid with beneficial metabolic effects.
This nutrient-dense food supports overall health in a number of ways, and dairy consumption has been linked to:
- Reduced risk of cardiovascular disease, stroke and high blood pressure1,2
- Improves metabolic health and reduces risk of type 2 diabetes3
- Reduce the risk of tooth decay4 And bone health improved5
- Probiotics found in fermented dairy products such as raw milk, raw cheese, yogurt, and kefir help maintain a healthy gut microbiome, thus improving gut health.6
Understanding Dairy Sensitivity
Dairy intolerance and dairy sensitivity are increasingly common problems, affecting millions of people and causing many to avoid dairy altogether (and thus miss out on essential nutrients and health benefits).
But what if there was a way for people with dairy issues to still enjoy the superfood benefits of milk, cheese, and yogurt? As it turns out, the answer may lie in understanding the difference between the A1 and A2 variants of the beta-casein protein found in dairy.
Dairy products contain two main types of protein: casein (which makes up about 80% of total protein) and whey (about 20%).
Casein Protein: Benefits and Variations
Of the two major milk protein fractions, the casein fraction actually offers more benefits. Casein has been shown to improve metabolism, protect against stress, and reduce tryptophan absorption.
According to Dr. Ray Pitt, “Casein, the main protein in milk, appears to have a direct anti-stress effect.” Specifically, studies have shown that casein may help protect against acute stress by protecting adrenal cortex activity and cortisol production.7
Casein affects the metabolic pathway of tryptophan, increasing its conversion to niacinamide (a beneficial compound) and decreasing the availability of free tryptophan in the body.8 Contrary to popular belief, serotonin is not the “happy hormone” we want more of.
Within the casein fraction, there are several subtypes, including alpha-casein, beta-casein, and kappa-casein. Beta-casein is the predominant form, accounting for about 40% of the total protein in milk.
The important thing to note is that there are two main variants of beta-casein protein, A1 and A2. The difference between the two comes down to a single amino acid in the 209 amino acid sequence that makes up the beta-casein polypeptide chain. In the A1 variant, the amino acid at position 67 is histidine. In the A2 variant, it is proline.
Digestive Effects of A1 vs A2 Beta Casein
This may seem like a minor change, but it can have a significant impact on how beta-casein is broken down during digestion. The proline found in the A2 variant forms a strong bond that makes it difficult for the protein to be broken down at that location. The histidine found in the A1 variant forms a weaker bond, making it easier for beta-casein to be broken down at that location.
When A1 beta-casein is broken down, it can release a peptide called beta-casomorphin-7 (BCM7). Some individuals’ bodies may have difficulty fully digesting and eliminating this BCM7 peptide, which can potentially lead to stomach upset and other unwanted effects.
A2 beta casein, on the other hand, is not broken down in a way that releases BCM7, which may make it easier for many people to digest. This is where the A1 vs. A2 distinction becomes especially important for people with dairy intolerance.
A1 vs A2: Sources and Research
So where do these different beta-casein variants come from? It largely depends on the breed of dairy animal.
Most commercially produced cow's milk in many parts of the world contains more of the A1 beta-casein variant. This is because most modern dairy breeds, such as Holstein, Friesian, and Jersey, naturally produce more A1 beta-casein.
On the other hand, milk products from certain heritage cow breeds, such as goat, sheep, buffalo, guernsey, and some Jersey breeds, tend to contain only the A2 beta-casein variant. Human breast milk also contains only the A2 form.
That is, people who have difficulty consuming regular cow's milk and dairy products may be better off consuming A2 dairy sources.
There is a growing body of research exploring potential health and digestibility differences between A1 and A2 dairy products. Several studies have shown that switching from regular cow’s milk (which contains both A1 and A2 beta caseins) to milk containing only the A2 variant can improve gastrointestinal symptoms and overall well-being.
For example, a 2017 randomized, double-blind, crossover study published in the European Journal of Clinical Nutrition looked at the effects of A1 versus A2 beta-casein on digestive symptoms. Researchers had 41 healthy adults consume milk containing either A1 or A2 beta-casein for two weeks, followed by a two-week washout period.9
Results showed that participants had significantly less abdominal pain, bloating, and constipation when they drank A2 milk compared to A1 milk. Interestingly, people who reported lactose intolerance also reported improved lactose tolerance when they drank A2 milk.
Another study published in the Nutrition Journal in 2019 looked at the effects of A1 versus A2 beta casein on gut inflammation. Researchers had 600 healthy adults consume either A1 or A2 milk for two weeks. They found that A2 milk reduced gut inflammation markers compared to A1 milk.10
Explore Dairy Substitutes
A 2020 review article published in the journal Nutrients summarized the evidence on A1 versus A2 dairy products, concluding that “consumption of cow's milk containing A2 instead of A1 improved overall gastrointestinal health and reduced milk intestinal discomfort.”11
The authors noted that this mechanism likely involves the formation of BCM7 from A1 beta-casein, which “may significantly contribute to the reported gastrointestinal symptoms associated with conventional cow's milk consumption.”
Importantly, this study suggests that these benefits may extend beyond those with diagnosed lactose intolerance or other overt dairy sensitivity. Even individuals who do not experience overt digestive upset from dairy products may find A2 dairy more easily tolerated.
Of course, individual responses may vary. Not everyone with dairy problems will experience the same degree of relief when switching to A2 dairy. Factors beyond the A1 vs. A2 beta-casein distinction can also affect dairy digestibility. For example, lactose intolerance, which is caused by a deficiency of the lactase enzyme needed to break down lactose, is a well-known problem for many people.
However, addressing underlying gut health or metabolic issues may also play an important role in increasing dairy tolerance over time.
For example, lactose intolerance can often improve over time as gut health and metabolic function are optimized. Research suggests that lactose intolerance may be associated with conditions such as small intestinal bacterial overgrowth (SIBO), which can impair the body’s ability to properly digest lactose.12 By addressing this underlying imbalance, many people have found that they can gradually incorporate dairy back into their diet.
Additionally, some people may have difficulty digesting dairy products containing microbial rennet, an alternative coagulant to the traditional animal rennet used in cheese making. More than 90 percent of North American cheeses are made using a genetically modified version called FPC (fermentation-produced chymosin), made by Pfizer.
There are two main problems with FPC used in cheese making: 1) toxicity (traces of genetically modified bacteria have been found in the enzyme);13 2) Digestive problems (cheese can act as an allergen and cause allergic reactions, digestive or respiratory problems)14) More information about this FPC can be found here.
So if you've ever eaten cheese before and had a digestive issue or allergic-like reaction, it may not be the dairy itself that's the problem, but rather the rennet type!
Finding Your Ideal Dairy Source
Dairy products are undoubtedly a powerhouse of nutrition, providing a wide range of essential vitamins, minerals, proteins, and other health-promoting compounds. For many people, dairy products can and should be an important part of a balanced, nutrient-dense diet.
By understanding the difference between A1 and A2 casein and experimenting with different dairy products, those with sensitivities can once again enjoy the benefits of this food group's superfoods.
A good place to start is by sourcing raw goat or raw sheep cheese, as these are naturally A2. You can also visit www.realmilk.com to find a dairy near you. This handy website connects you with local dairy farms. Ask them how they raise their animals, what they feed their animals, and whether they have been tested and verified for A2A2.
And the excitement doesn’t end there. The team at Nourish Cooperative has been working hard to slowly expand their exclusive Mercola cheese box, delivering the highest quality cheese you can find straight to your doorstep. The delicious cheeses are made from 100% grass-fed, vaccine-free A2 milk and traditional animal rennet for the ultimate in purity.
As more small cheese producers join the project, the selection expands, so join our waiting list here to get your hands on this irresistible traditional A2 cheese.
About the Author
Ashley Armstrong is the co-founder of Angel Acres Egg Co., specializing in low-PUFA (polyunsaturated fat) eggs that ship to all 50 states (join the waitlist here) and the co-founder of Nourish Cooperative, which ships low-PUFA pork, beef, cheese, A2 dairy, and traditional sourdough to all 50 states. Waitlist will be opening again soon.
