Understanding the Differences in Dairy Proteins
Milk protein consists of two main types: casein and whey. Casein, which makes up about 80% of milk protein, has different variants, including A1 and A2 beta-casein. The crucial difference lies in a single amino acid at position 67 of the protein chain. In A1 beta-casein, this position holds a histidine amino acid, whereas in A2 beta-casein, it is a proline. This seemingly minor variation has significant implications during digestion, especially for sensitive individuals.
The Impact of A1 Beta-Casein Digestion
When A1 beta-casein is digested, the histidine at position 67 allows it to be broken down into a peptide called beta-casomorphin-7 (BCM-7). This opioid-like peptide has been linked in some studies to gastrointestinal discomfort, including symptoms similar to lactose intolerance like bloating, gas, and abdominal pain. BCM-7 has also been suggested to contribute to inflammation and delayed gut motility. In contrast, the proline in A2 beta-casein creates a stronger bond that prevents the release of significant amounts of BCM-7, resulting in a potentially gentler digestive experience.
The Source of A1 Protein in Cheese
The presence of A1 protein in cheese directly correlates with the milk used in its production. Most commercial cow's milk in the U.S. and many other parts of the world comes from conventional herds, like Holsteins, that produce a mixture of A1 and A2 beta-casein. Therefore, the majority of mass-produced cheeses made from cow's milk will contain A1 protein.
Which Cheeses Contain A1 Protein?
Many common cheeses derived from regular cow's milk, especially those from breeds like Holstein and Friesian, are likely to contain A1 protein. This includes popular options like:
- Cheddar
- American cheese
- Mozzarella
- Gouda
- Swiss
The A2 Difference in Cheese Production
To create A2-only cheese, dairy producers must source milk exclusively from cows that are genetically tested to produce only the A2 beta-casein variant. Breeds like Jersey and Guernsey, or specifically selected A2 herds, are used for this purpose. The A2-only milk is then processed separately to produce cheese free of A1 protein, which is often marketed as 'A2 cheese'.
Naturally A1-Free Cheese Options
For those sensitive to A1 protein, some dairy alternatives are naturally A1-free and may offer better digestibility. These include cheeses made from the milk of:
- Goats: Goat's milk and cheeses like chevre and feta contain mostly A2 beta-casein.
- Sheep: Cheeses made from sheep's milk, such as manchego or pecorino romano, are naturally A2-based.
- Buffalo: Milk from buffalo, used for authentic buffalo mozzarella, is another source of naturally A2-only dairy.
Navigating the A1 vs. Lactose Conundrum
It is important to distinguish between sensitivity to A1 protein and lactose intolerance. Lactose intolerance is caused by the inability to digest lactose, the sugar in milk, due to a lack of the enzyme lactase. A1 protein sensitivity, on the other hand, is an issue with the protein itself. While some people with self-reported lactose intolerance may find that A2 milk or cheese eases their symptoms, this is due to avoiding the A1 protein, not the lactose. For a true lactose intolerance, switching to lactose-free milk or cheese is the appropriate solution.
A Comparison of A1 and A2 Beta-Casein Dairy
| Feature | A1 Beta-Casein Dairy (Most Conventional Cow's Milk) | A2 Beta-Casein Dairy (A2 milk, goat, sheep, buffalo) |
|---|---|---|
| Source Breeds | Holstein, Friesian, and other Northern European cow breeds. | Jersey, Guernsey, and some African/Southern French cow breeds; also goats, sheep, and buffalo. |
| Peptide Release | Can release BCM-7 during digestion. | Produces little to no BCM-7 during digestion. |
| Digestive Effects | Linked to symptoms like bloating, gas, and abdominal pain in sensitive individuals. | Associated with fewer digestive issues for some people. |
| Inflammatory Response | May increase inflammatory markers in the gut. | Often associated with a reduced inflammatory response. |
| Protein Digestion | May slow food transit time for some. | Typically digests more easily and efficiently. |
Conclusion: Making Informed Cheese Choices
In summary, the presence of A1 protein in cheese is dependent on the milk source. Traditional cow's milk cheeses from breeds common in Northern Europe typically contain both A1 and A2 beta-casein, and for some, this can lead to digestive discomfort. However, cheeses made from goat's milk, sheep's milk, or from certified A2-only cow's milk herds are naturally A1-free and may be a better option for those with sensitivities. The scientific debate surrounding the broader health effects of A1 beta-casein is ongoing and warrants further research, but for individuals seeking better digestive tolerance, exploring A1-free options is a well-founded strategy.
For more research on the health effects of A1 and A2 milk, see this scientific review.
