Understanding the Milk Grading System
In the United States, milk is classified by a regulatory grading system that primarily addresses safety and sanitary conditions for production and processing. The two main grades are Grade A and Grade B. The vast majority of milk sold for fluid consumption in retail stores, such as whole, skim, and low-fat, is Grade A.
Grade A milk is regulated under the Pasteurized Milk Ordinance (PMO), a set of guidelines that state agencies adopt to ensure strict sanitary requirements are met. This includes rigorous bacterial testing, with the raw milk required to meet a maximum bacterial plate count and coliform count. These strict standards are in place to ensure the milk is safe for drinking and pasteurization. Grade B milk, or manufacturing grade milk, does not meet these same stringent standards and is used for manufactured dairy products like cheese and butter, not for fluid consumption.
The Genetic Difference: A1 vs. A2 Protein
Separately from quality grading, milk is also characterized by its genetic protein makeup, specifically the variants of beta-casein protein. All cow's milk contains beta-casein, but the protein can exist in different variants due to a genetic mutation. Historically, cows produced only A2 beta-casein, but a genetic mutation led to the emergence of the A1 variant in many modern breeds.
- A1 Beta-Casein: Found primarily in milk from Western European cow breeds like Holsteins and Friesians. During digestion, A1 beta-casein can release a peptide called beta-casomorphin-7 (BCM-7). Some research suggests this peptide can cause digestive discomfort and inflammation in sensitive individuals, mimicking symptoms of lactose intolerance.
- A2 Beta-Casein: Considered the original beta-casein variant, it is found in milk from breeds like Jerseys, Guernseys, and many traditional Indian and African breeds. A2 beta-casein digests differently and does not release the BCM-7 peptide in the same manner, leading some to believe it is easier on the digestive system.
A2 milk is produced from cows that have been specifically genotyped to produce milk containing only the A2 beta-casein protein and no A1 protein.
Why Grade A and A2 are Not Mutually Exclusive
It is entirely possible for milk to be both Grade A and A2. The Grade A label simply confirms that the milk was produced and processed under sanitary conditions safe for human consumption. The A2 label is an additional, separate designation that specifies the genetic protein variant present in the milk.
A product can be Grade A milk that contains a mix of A1 and A2 proteins, which is common for milk from conventional herds. Conversely, a specialty product like A2 Milk from a company like The a2 Milk Company will also meet Grade A sanitary standards to be sold for fluid consumption. The two concepts are not a comparison of one versus the other, but rather different classification criteria for the same product.
Comparison Table: Grade A vs. A2 Milk
| Feature | Grade A Milk | A2 Milk |
|---|---|---|
| Definition | A regulatory classification for milk that meets specific health and sanitary standards for fluid consumption. | A marketing term for milk that contains only the A2 beta-casein protein and no A1 protein. |
| Classification Focus | Hygiene, sanitation, and microbial quality of the processing environment. | Genetic makeup of the beta-casein protein variant in the cow's milk. |
| Governing Body | State and federal health agencies, under guidelines from the Pasteurized Milk Ordinance (PMO). | Private companies and specialized dairy farmers who test and segregate herds. |
| Availability | The vast majority of milk sold for drinking in supermarkets, regardless of brand or type. | A specialty product found in dairy sections, often from specific brands and at a higher price point. |
| Nutritional Profile | Standard nutritional profile for cow's milk, but can contain both A1 and A2 beta-casein. | Nutritionally similar to regular milk, but with the specific A2 beta-casein protein only. |
| Digestive Impact | Varies, as it may contain A1 protein which can cause digestive issues for some sensitive individuals. | May be easier for some people to digest if they are sensitive to the BCM-7 peptide released by A1 protein. |
The Bottom Line: Interpreting Milk Labels
When you see a carton of milk labeled "Grade A," it simply means it has passed the required safety and quality controls for liquid milk sold in stores. This is a standard designation and says nothing about the genetic composition of the milk's protein. When you see a carton labeled "A2 Milk," it implies that the milk comes from a specific type of cow that has been tested and certified to produce only the A2 beta-casein protein.
For most consumers, Grade A milk is the standard product. Those with specific digestive sensitivities to dairy, who may experience discomfort but are not truly lactose intolerant, might seek out A2 milk as a potential alternative. However, A2 milk is not a replacement for lactose-free milk for those with diagnosed lactose intolerance, as it still contains lactose. The decision between Grade A and A2 milk, or a Grade A and A2 product, ultimately depends on your individual health needs and how your body responds to different types of dairy protein. More and more dairy producers are recognizing the market for A2 milk and are offering Grade A milk that is also certified to contain only the A2 beta-casein.
Conclusion: Grade A and A2 are Distinct Concepts
To summarize, the core distinction is that Grade A is a standard of sanitary production, while A2 is a genetic characteristic related to the type of protein in the milk. A milk product can be both Grade A and A2, or just Grade A. Consumers should not confuse the two classifications. The Grade A label assures safety and quality, but the A2 label indicates a potentially easier-to-digest milk for those sensitive to the A1 beta-casein protein found in conventional dairy. Understanding both terms allows for a more knowledgeable choice at the grocery store.
