Why do people buy A2 milk? Unlocking the digestive and nutritional differences

January 11, 2026 •

4 min read

While standard milk contains a mix of A1 and A2 beta-casein proteins, a growing number of consumers are switching to A2 milk, which contains only the A2 protein. This shift is primarily driven by anecdotal reports and emerging research suggesting that A2 milk is easier to digest for some individuals.

Quick Summary

A2 milk is gaining popularity for its potential digestive benefits, as it only contains the A2 beta-casein protein, unlike regular milk with both A1 and A2 proteins. The absence of the A1 protein and its digestion-related peptides may lead to reduced discomfort for sensitive individuals.

Key Points

Easier Digestion: A2 milk may be gentler on the stomach for individuals who experience discomfort from regular milk due to its unique protein composition.
No BCM-7 Peptide: The A1 beta-casein protein in regular milk releases a peptide called BCM-7 during digestion, which is avoided when consuming A2 milk.
Contains Same Nutrients: A2 milk provides the same essential nutrients, including protein, calcium, and vitamins, as regular milk.
Not for Allergies: A2 milk is not a solution for a medically diagnosed cow's milk protein allergy, as it still contains milk protein.
Not Lactose-Free: It contains the same amount of lactose as regular milk, unless explicitly labeled as a lactose-free version.
Potential Gut Health Benefits: Some research suggests A2 milk may promote beneficial changes in gut bacteria and reduce markers of inflammation.
Higher Cost: Due to the specialized sourcing from genetically-tested herds, A2 milk is generally more expensive than regular milk.

Understanding the difference between A1 and A2 milk

At its core, the reason why people buy A2 milk comes down to a small, yet significant, genetic difference in dairy cows. Most commercially available milk today comes from cows, like Holstein Friesians, that produce a combination of A1 and A2 beta-casein protein. However, the A2 protein is the older, original variant and is still produced by some cow breeds, like Jerseys and Guernseys, as well as humans, sheep, and goats. The key distinction lies in how these two protein variants are broken down during digestion.

The role of BCM-7 in digestive discomfort

When the A1 beta-casein protein is digested, it can release a peptide called beta-casomorphin-7 (BCM-7). BCM-7 is an opioid-like compound that has been linked to a variety of gastrointestinal symptoms, including bloating, gas, and abdominal discomfort in some people. By contrast, the A2 protein does not release BCM-7 during digestion. This crucial difference in the digestive process is the primary reason many individuals sensitive to regular milk find relief when they switch to A2 milk, as their discomfort may be linked to the A1 protein rather than lactose.

A2 milk's potential impact on gut health and beyond

Research on A2 milk's broader effects is still emerging, but some studies point to additional health benefits beyond just easing digestion. For instance, a 2025 study on individuals with GI discomfort found that A2 milk consumption significantly altered their gut microbiota composition, promoting beneficial microbes like Bifidobacterium and Blautia. This shift was negatively correlated with fecal calprotectin, an inflammatory marker, suggesting A2 milk may have anti-inflammatory effects in the gut. The study's authors theorize that A2 milk supports better gut health, which is a major factor in overall immune function.

Potential benefits of A2 milk

Easier digestion: Reduced symptoms of gas, bloating, and abdominal pain for those sensitive to the A1 protein.
Improved gut microbiome: Some research shows that A2 milk can increase the abundance of beneficial bacteria in the gut, which may support better digestive and immune health.
Reduced gut inflammation: Studies suggest a link between A1 protein consumption and increased inflammatory markers, which is not seen with A2 milk.
Rich nutritional profile: A2 milk retains all the same essential nutrients as regular cow's milk, such as calcium, protein, potassium, and vitamin D, without the potential digestive side effects of A1 protein.
Option for lactose-sensitive individuals: While not lactose-free, many who self-diagnose as lactose intolerant discover their symptoms are actually tied to the A1 protein. These individuals may tolerate A2 milk better.

Nutritional comparison: A2 milk vs. Regular (A1/A2) milk


Feature	A2 Milk	Regular (A1/A2) Milk
Beta-Casein Protein	Contains only A2 beta-casein.	Contains both A1 and A2 beta-casein.
Digestion	Easier for some sensitive individuals; does not release BCM-7.	Digestion can release BCM-7, potentially causing discomfort.
Macronutrients	Same amount of protein, fat, and calories (depending on variety).	Same amount of protein, fat, and calories (depending on variety).
Micronutrients	Same amount of calcium, potassium, and vitamins.	Same amount of calcium, potassium, and vitamins.
Lactose Content	Contains lactose (unless labeled otherwise).	Contains lactose.
Suitability for Allergies	Not suitable for those with a cow's milk protein allergy.	Not suitable for those with a cow's milk protein allergy.

Making the switch to A2 milk

For those who experience digestive issues after drinking regular cow's milk, switching to A2 milk is a worthwhile experiment. It is important to remember that A2 milk is not lactose-free, so it will not address symptoms stemming from a true lactose intolerance. However, many people confuse A1 protein sensitivity with lactose intolerance, and A2 milk can provide a dairy option without the associated discomfort. Because A2 milk comes from specially-selected herds of cows that are genetically tested to produce only the A2 protein, it is typically more expensive than regular milk. The increased cost reflects the specialized farming and testing processes required to ensure its purity. Consumers interested in learning more about A2 milk and its production can find a wealth of information from reputable sources and research, such as the National Institutes of Health.

The bottom line

Ultimately, the choice to buy A2 milk is a personal one, often motivated by the desire to alleviate digestive discomfort while continuing to enjoy the nutritional benefits of dairy. For individuals who have experienced unpleasant symptoms from regular milk, a trial of A2 milk may reveal that the A1 protein was the real issue. With the same nutritional profile as conventional milk but without the A1 protein, A2 milk offers a promising solution for those seeking a gentler dairy option.

Frequently Asked Questions

The main difference lies in the type of beta-casein protein they contain. Regular milk typically has a mix of A1 and A2 proteins, while A2 milk only contains the A2 protein.

For some people who are sensitive to the A1 beta-casein protein, A2 milk is easier to digest. This is because the A1 protein can release a peptide called BCM-7 during digestion, which is not released from the A2 protein.

Yes, A2 milk contains lactose, the natural sugar found in milk, unless it is specifically labeled as 'lactose-free.' It will not solve problems caused by genuine lactose intolerance.

A2 milk comes from specific herds of dairy cows that are genetically tested to ensure they only produce the A2 beta-casein protein. The milk is then processed and bottled separately from regular milk.

A2 milk is generally considered safe. However, it is still a dairy product and not suitable for individuals with a medically diagnosed cow's milk protein allergy. Anyone with concerns should consult a doctor.

No, A2 milk has a virtually identical nutritional profile to regular milk, providing the same levels of protein, calcium, and other essential nutrients. The difference is solely in the type of beta-casein protein.

The higher price is due to the specialized processes involved in producing A2 milk. This includes the cost of genetically testing herds and keeping A2-producing cows separate, which adds to the overall production costs.