How do they make milk with no lactose?

December 31, 2025 •

4 min read

Globally, an estimated 65% of the population has a reduced ability to digest lactose after infancy, leading to digestive issues for many. This is why the question of how do they make milk with no lactose is so important for those seeking to enjoy dairy without uncomfortable side effects. Thankfully, modern food technology provides two effective methods to achieve this.

Quick Summary

Lactose-free milk is produced by either adding the lactase enzyme to regular cow's milk to break down the natural sugar or using advanced filtration to remove the lactose entirely. The resulting milk offers the same nutritional benefits without digestive discomfort.

Key Points

Lactase Enzyme Addition: The most common method involves adding the lactase enzyme to milk, which breaks down the lactose into more digestible simple sugars.
Filtration Technology: An alternative, more complex process uses ultrafiltration and nanofiltration to physically separate and remove a percentage of the lactose from the milk.
Sweeter Taste Profile: Milk made with the lactase enzyme method tastes slightly sweeter because the resulting glucose and galactose are perceived as sweeter by the taste buds than the original complex lactose sugar.
Maintains Nutritional Value: Lactose-free milk contains the same high levels of protein, calcium, vitamins, and minerals as regular milk, as the processing does not strip away these nutrients.
Not for Milk Allergies: It's crucial to distinguish between lactose intolerance and a milk allergy; lactose-free milk is still a dairy product and not safe for those with a milk protein allergy.
Extended Shelf Life: Because the lactase enzyme works over time to break down lactose, it also prevents spoilage, giving lactose-free milk a longer shelf life compared to regular milk.

Understanding Lactose and Lactose Intolerance

Lactose, a complex sugar (disaccharide) found naturally in milk, is made of two simpler sugars: glucose and galactose. For most people, the small intestine produces an enzyme called lactase to break down lactose into these simple sugars for absorption. However, people with lactose intolerance produce insufficient amounts of lactase, meaning undigested lactose travels to the large intestine where gut bacteria ferment it, causing gas, bloating, cramps, and diarrhea. Lactose-free milk provides a solution to this issue by either removing or breaking down the lactose before consumption.

The Primary Method: Adding the Lactase Enzyme

The most common and cost-effective method to create lactose-free milk is to add the lactase enzyme directly to pasteurized milk. This process, often done in large cooling tanks, mimics what the human body's digestive system does naturally.

A Closer Look at the Lactase Process

Standardization and Pasteurization: The process begins with regular cow's milk, which is standardized to the desired fat content (e.g., skim, 2%, or whole) and pasteurized to kill harmful bacteria.
Enzyme Addition: A precise amount of the commercially produced lactase enzyme is added to the milk after pasteurization and cooling. This is often done to maintain a stable, longer-lasting product.
Hydrolysis (Breakdown): The enzyme is given time to break down the lactose into glucose and galactose through a process called hydrolysis. The longer the incubation, the more lactose is broken down, and the sweeter the milk will taste.
Testing and Packaging: The milk is tested to ensure lactose levels are below the required threshold for a 'lactose-free' label. Once confirmed, the milk is often re-pasteurized and then packaged for distribution.

The Filtration Method for Lactose Removal

For a less sweet, more neutral-tasting product, some manufacturers use advanced filtration methods to physically remove the lactose.

Ultrafiltration (UF) and Nanofiltration (NF)

Ultrafiltration (UF): In this step, milk is passed through specialized membranes that separate its components based on molecular size. Larger molecules like protein and fat are retained, while smaller molecules like water, minerals, and lactose pass through the filter. This process can remove a significant portion of the lactose, creating a less sweet profile.
Nanofiltration (NF): This further refines the process by using even smaller pores to selectively remove more lactose and concentrate minerals, which can later be added back into the milk.
Enzyme Finishing: Even with filtration, a small amount of lactase may still be added to break down any remaining lactose to ensure the milk is truly lactose-free.

Comparison: Enzyme vs. Filtration Production

Nutritional Profile of Lactose-Free Milk

Despite the processing, lactose-free cow's milk maintains the same excellent nutritional profile as regular milk. It remains a fantastic source of essential vitamins and minerals:

Protein: Provides about 8 grams of complete protein per cup.
Calcium: An excellent source for bone health, often providing around 300 mg per cup.
Vitamin D: Many brands fortify their milk with vitamin D to aid in calcium absorption.
Other Vitamins: Still contains important vitamins like B12 and riboflavin.

Lactose-Free Dairy Products and Alternatives

The technology used to create lactose-free milk has also enabled the creation of other dairy products. In addition to fluid milk, consumers can find:

Lactose-free yogurt
Lactose-free ice cream
Lactose-free cheeses (some hard cheeses are naturally low in lactose)
Lactose-free butter

It is important to note that lactose-free milk is still a dairy product and is not suitable for individuals with a dairy allergy, as it still contains milk proteins like casein and whey. For those with a dairy allergy or who follow a vegan diet, plant-based alternatives like almond, soy, and oat milk are necessary.

Conclusion

In conclusion, the production of lactose-free milk relies on two primary methods: the enzymatic breakdown of lactose with lactase or its physical removal through advanced filtration. The former is a simpler, more common process resulting in a sweeter milk, while the latter offers a more neutral taste profile. Both methods successfully create an easy-to-digest dairy product with the same nutritional benefits as regular milk, providing a valuable option for millions with lactose intolerance to enjoy dairy once more. While not suitable for those with milk protein allergies, it represents a significant advancement in food technology and dietary inclusivity.

Learn more about the science of food production from trusted sources.

This is an example of an optional outbound link.

Frequently Asked Questions

The primary method for making lactose-free milk involves adding the lactase enzyme to regular pasteurized milk. The enzyme breaks down the natural milk sugar, lactose, into simpler, more digestible sugars: glucose and galactose.

Yes, lactose-free milk is often slightly sweeter than regular milk. This is because the lactase enzyme breaks down the complex lactose sugar into simple sugars (glucose and galactose), which our taste buds perceive as sweeter.

Yes, lactose-free milk retains the same excellent nutritional profile as regular milk. It is a great source of protein, calcium, and vitamins A, D, and B12.

No, lactose-free milk is not safe for people with a milk protein allergy. It is still a dairy product containing milk proteins like casein and whey, which are the allergy triggers.

The filtration method involves passing milk through specialized membranes (ultrafiltration or nanofiltration) with tiny pores. These membranes physically remove the larger lactose molecules from the milk, which is then recombined and finished with a small amount of lactase.

Lactose-free milk typically has a longer shelf life because the breakdown of lactose also helps prevent spoilage. The addition of lactase after pasteurization contributes to its extended freshness.

For most people with lactose intolerance, there are no side effects. However, some may be sensitive to thickening agents used in certain brands, and individuals with diabetes should be aware of a potentially faster blood sugar spike due to the simpler sugars.

Yes, lactose-free milk can be used for cooking and baking just like regular milk. Its nutritional profile and texture are nearly identical, and the slightly sweeter taste is often not noticeable in the final product.