Does Lactase Enzyme Remove Lactose from Milk?

January 2, 2026 •

3 min read

According to research, approximately 65% of the world's population has a reduced ability to digest lactose, the sugar found in milk. So, does lactase enzyme remove lactose from milk to make it more digestible? Yes, lactase acts as a natural biological tool to break down the complex milk sugar, converting it into simpler, more absorbable sugars.

Quick Summary

This article explains how the lactase enzyme breaks down lactose into glucose and galactose, detailing the process for both commercial lactose-free milk and at-home use of supplements. It also covers the implications for lactose intolerance and compares different product types.

Key Points

Lactase is an Enzyme: It is produced in the small intestine to break down lactose, the sugar in milk.
Not Removed, but Broken Down: The lactase enzyme doesn't physically remove the lactose but chemically breaks it into simpler, more digestible sugars: glucose and galactose.
Used Commercially: Manufacturers add lactase enzyme to milk to create the lactose-free products found in stores.
Available as Supplements: Lactase supplements in pill or drop form can help individuals with intolerance digest lactose-containing foods.
Alters Taste: The process makes milk sweeter because the simple sugars (glucose and galactose) are perceived as sweeter than the original lactose molecule.
Maintains Nutritional Value: Lactose-free milk retains the same protein, calcium, and vitamin content as regular milk.
Lactase Drops vs. Pills: Drops are for pre-treating liquid dairy, while pills are for immediate consumption with dairy foods.

Understanding Lactase and Lactose

Lactose is a disaccharide, or complex sugar, naturally present in milk and other dairy products. To digest it, the human body produces an enzyme called lactase in the small intestine. Lactase's job is to break down the lactose molecule into two simpler, more easily absorbed sugars: glucose and and galactose. When someone lacks sufficient lactase, the undigested lactose travels to the large intestine, where it is fermented by gut bacteria, causing uncomfortable symptoms like bloating, gas, and abdominal pain.

The Enzymatic Breakdown Process

When lactase enzyme is added to milk, a chemical reaction known as hydrolysis occurs. The lactase acts as a catalyst, speeding up the breakdown of the lactose molecule ($ ext{C}{12} ext{H}{22} ext{O}{11}$) into its two component monosaccharides, glucose ($ ext{C}{6} ext{H}{12} ext{O}{6}$) and galactose ($ ext{C}{6} ext{H}{12} ext{O}_{6}$). This process is exactly how commercially produced lactose-free milk is made.

Manufacturers: Dairy companies add lactase enzyme directly to milk during the production process. The milk is held for a period, allowing the enzyme to break down the lactose before it is packaged and sold.
Consumers: Individuals with lactose intolerance can add lactase drops to their own milk or dairy products at home to achieve a similar result.

This breakdown process is highly effective. In fact, studies show that adding enough lactase can hydrolyze over 90% of the lactose in milk. The final product contains little to no lactose, making it safe and easy to digest for most individuals with an intolerance.

Is the Lactose Completely Gone?

While the goal is to make a product "lactose-free," the term often refers to products with a significantly reduced lactose content. Most commercial products remove the vast majority of lactose. For example, some dairy producers first pass milk through filters to remove around 40% of the lactose before adding the lactase enzyme to break down the remaining amount. The final product is digestible for people with lactose intolerance because it removes the specific molecule that causes digestive distress, not because the milk itself is physically altered beyond its sugar content.

Lactase Products: Drops vs. Pills

For personal use, lactase is available in two primary forms: drops and pills (or capsules).

Lactase Drops:

Application: Added directly to liquid dairy products like milk or cream.
How it works: The enzyme breaks down the lactose before consumption. For example, adding a few drops to a carton of milk and refrigerating it for 24 hours can significantly reduce the lactose content.
Best for: Pre-treating dairy products that will be consumed at a later time. Not ideal for solid foods like cheese.

Lactase Pills/Capsules:

Application: Taken orally just before consuming dairy foods or drinks.
How it works: The enzyme is released in the digestive tract to break down the lactose as it is consumed.
Best for: Spontaneous consumption of dairy, such as eating cheese, yogurt, or having a dish that unexpectedly contains dairy.


Feature	Lactase Drops	Lactase Pills/Capsules
Usage	Add to liquid dairy before consumption.	Take with the first bite of dairy food.
Timing	Pre-treatment; requires advanced planning.	Immediate; for on-the-spot relief.
Best For	Milk, cream, infant formula.	All dairy products, including solid foods like cheese and ice cream.
Mechanism	Converts lactose in the food product itself.	Aids the body's digestive process from within.

The Impact on Taste

When lactase breaks down lactose into glucose and galactose, the milk becomes noticeably sweeter. This is because glucose and galactose are simpler sugars and are perceived as sweeter by the taste buds than the more complex lactose molecule. This subtle sweetness is why lactose-free milk often tastes slightly different from regular milk, though its nutritional profile remains largely the same.

Conclusion

In summary, yes, the lactase enzyme removes lactose from milk by breaking it down into smaller, digestible sugars. This process is used both commercially to create lactose-free dairy products and by individuals with lactose intolerance using lactase supplements. While the resulting milk tastes slightly sweeter, it retains all the same nutritional benefits as regular milk. For those with lactose intolerance, this enzymatic process is a reliable method for enjoying dairy without digestive discomfort, making it an essential tool in modern food science. For further information, the National Center for Biotechnology Information has additional details on lactase and its uses.

Frequently Asked Questions

The primary function of the lactase enzyme is to break down lactose, a complex milk sugar, into the simple sugars glucose and galactose, which are then easily absorbed by the body.

Manufacturers produce lactose-free milk by adding the lactase enzyme directly to cow's milk during processing. This enzyme breaks down the lactose before the milk is bottled and sold.

Yes, lactose-free milk contains the same nutrients as regular milk, including protein, calcium, phosphorus, and vitamins. The only significant difference is the reduced lactose content.

Lactose-free milk tastes sweeter because the lactase enzyme has broken down the lactose into glucose and galactose. These two simple sugars are naturally sweeter to our taste buds than the original complex lactose molecule.

Lactase supplements in pill or capsule form are effective for digesting lactose in all types of dairy products, including milk, cheese, and ice cream, when taken at the time of consumption.

No, lactose intolerance is not the same as a dairy allergy. Lactose intolerance is a digestive issue caused by a lactase deficiency, while a dairy allergy is an immune system response to milk proteins, which can cause severe reactions.

For many people with lactose intolerance, lactase supplements effectively prevent the symptoms associated with lactose digestion, such as bloating and gas. However, the effectiveness can vary depending on the individual and the dosage.