Is Costco A2 Milk Lactose-Free?

December 5, 2025 •

3 min read

A2 milk contains the same amount of lactose as regular cow's milk. While Costco offers A2 milk, it is not inherently lactose-free, and this distinction is crucial for those with dairy sensitivities to understand. The benefit of A2 milk lies in its single type of beta-casein protein, not in the absence of lactose.

Quick Summary

A2 milk, including Costco's Kirkland Signature brand, is not lactose-free and contains milk sugar. The primary difference is the type of beta-casein protein, which some people find easier to digest, potentially alleviating symptoms for those with an A1 protein sensitivity rather than true lactose intolerance.

Key Points

Not Lactose-Free: Costco's A2 milk contains lactose, the sugar found in regular dairy, and is not suitable for individuals with a medically diagnosed lactose intolerance.
A1 vs. A2 Protein: The key difference is the type of protein; A2 milk lacks the A1 protein that forms the peptide BCM-7, which can cause digestive issues for some people.
Addresses Protein Sensitivity: A2 milk is intended for those whose digestive discomfort is triggered by the A1 protein, not by the lactose sugar.
Still a Dairy Product: Despite being easier to digest for some, A2 milk is still a dairy product and retains the same nutritional value as regular milk.
Look for "Lactose-Free": Shoppers with a true lactase deficiency should look for products specifically labeled "lactose-free," such as the Kirkland Signature Organic Lactose Free milk available at Costco.
Consult a Doctor: It's wise to speak with a healthcare professional to determine if your symptoms are from lactose intolerance or A1 protein sensitivity before making a dietary change.

Understanding the Difference: Lactose vs. A1 Protein

When seeking alternatives to conventional dairy, it's easy to confuse different sensitivities. The primary issue for people with lactose intolerance is a deficiency of the enzyme lactase, which is needed to break down lactose, the sugar found in milk. On the other hand, some people experience digestive discomfort, such as bloating and gas, due to the A1 beta-casein protein. This is where A2 milk offers a potential solution, but it is important to realize that addressing one issue does not resolve the other.

Regular milk from most herds contains a mixture of A1 and A2 beta-casein proteins. The A1 protein, upon digestion, releases a peptide called beta-casomorphin-7 (BCM-7). For some individuals, BCM-7 can cause digestive issues that mimic the symptoms of lactose intolerance, which is why some find relief with A2 milk, even though it still contains lactose. A2 milk comes from specially selected cows that naturally produce only the A2 beta-casein protein, eliminating the troublesome BCM-7 peptide.

What Costco Offers: A2 Milk vs. Lactose-Free Milk

At Costco, shoppers can find both A2 milk and genuine lactose-free milk products. The Kirkland Signature Organic Whole Milk, which contains A2 protein, is not lactose-free and will cause symptoms for those with lactase deficiency. Conversely, Costco also carries Kirkland Signature Organic Lactose Free milk, which is chemically treated with the lactase enzyme to remove the lactose sugar, making it suitable for those with lactose intolerance. This distinction means that individuals must read product labels carefully to select the correct item for their specific dietary needs.

How to know if you're sensitive to A1 protein or lactose

For many, discerning the source of their digestive distress can be challenging. A trial-and-error approach can be effective for those who are unsure. By trying a pure A2 milk product, such as the one available at Costco, you can test for a potential A1 protein sensitivity. If symptoms subside, it's likely the A1 protein was the culprit. However, if discomfort persists, it suggests a problem with lactose, requiring a switch to a certified lactose-free product.

This simple, observational test can provide valuable insight into the true nature of one's milk intolerance. Since A2 milk is a natural dairy product, it still offers the same nutritional benefits as regular milk, including calcium, protein, and vitamins A and D, making it a viable option for those who can tolerate dairy but not A1 protein.

Comparing Milk Types for Digestive Health


Feature	Regular Milk (A1 & A2)	A2 Milk (Only A2)	Lactose-Free Milk	Plant-Based Milks
Lactose Content	Contains lactose	Contains lactose	Lactose removed	Lactose-free
A1 Protein Content	Contains A1 protein	Contains NO A1 protein	Contains A1 protein (unless filtered)	Contains NO animal protein
Primary Benefit	Standard nutrition	Potentially easier on digestion for A1 sensitive	Digestible for lactose intolerant	Dairy-free alternative
Common Sensation	Possible digestive upset	Less digestive upset for some	No lactose-related discomfort	Diverse flavor and texture
Best For	Those with no milk sensitivity	A1 protein sensitivity	Lactase deficiency	Vegans, dairy allergies

The Rise of A2 Milk's Popularity

The growing interest in A2 milk can be attributed to increased consumer awareness of specific protein sensitivities and a greater focus on digestive wellness. Historically, all cows produced only A2 milk, and this genetic trait is still found in certain breeds and in milk from some regions. The a2 Milk Company developed a method to test cows' genetics, allowing for the segregation of A2 herds and the exclusive production of A2 milk. This has led to the product's availability in major retailers like Costco, offering a new choice for many seeking an alternative to conventional dairy without sacrificing the nutritional benefits of real cow's milk.

Conclusion

In summary, Costco's A2 milk is not lactose-free, and it should be avoided by those with medically diagnosed lactose intolerance. Its primary benefit is that it contains only the A2 beta-casein protein, which some individuals find easier to digest than the A1 protein found in most regular milk. For those with genuine lactose intolerance, the appropriate choice would be Costco's lactose-free milk or another dairy-free alternative. Ultimately, understanding the difference between milk protein and milk sugar is essential for making an informed decision about which milk is best for your digestive health.

Important consideration: Those with diagnosed milk allergies should avoid all cow's milk products, including A2 milk.

Frequently Asked Questions

No, A2 milk contains the same amount of lactose as regular milk and will not provide relief for someone with a true lactose intolerance. For lactose intolerance, you need lactose-free milk or a non-dairy alternative.

A2 milk may be easier to digest for some people because it only contains the A2 beta-casein protein, not the A1 protein. During digestion, the A1 protein can release a peptide called BCM-7, which has been linked to digestive discomfort in sensitive individuals.

No, A2 milk is still a cow's milk product and contains milk protein. Those with a medically diagnosed cow's milk protein allergy should avoid A2 milk entirely and opt for a plant-based alternative.

Yes, Costco carries its own Kirkland Signature Organic Lactose Free milk, which has been treated with the lactase enzyme to make it digestible for those with lactose intolerance.

You can try a personal experiment by switching to A2 milk for a couple of weeks and monitoring your symptoms. If your digestive issues improve, it suggests a sensitivity to the A1 protein. If not, lactose is the likely cause.

No, A2 milk has the same nutritional profile as regular cow's milk, providing essential nutrients like calcium, protein, and vitamins A and D. The only difference is the type of beta-casein protein present.

A2 milk often costs more because it comes from specially selected cows that have been genetically tested and bred to produce only the A2 protein. This process adds a premium to the production cost.