Why is lactose-free milk harmful?

Lactose — is a disaccharide composed of two monosaccharides:

• Glucose
• Galactose

In people with lactase deficiency (lactose intolerance), the production of the enzyme lactase, which breaks down lactose into these two components, is impaired or absent. To make milk "lactose-free," manufacturers add the enzyme lactase to the product itself. As a result:

• Lactose is completely broken down into glucose and galactose before consumption.
• The resulting product formally contains no lactose, but it does contain its components

Although the mass fraction of carbohydrates in grams does not increase,:

• Lactose has a lower sweetness (≈ 0.2 of the sweetness of sucrose)
• Glucose and galactose — are significantly sweeter (glucose ≈ 0.7, galactose ≈ 0.3)
• Therefore, the taste perception of sweetness is 2–3 times higher than in whole milk

Additionally, some lactose-free varieties add extra glucose or syrups to enhance flavor. This can actually increase the amount of rapidly absorbable sugars compared to regular milk.

How this affects the body:

1. Rapid increase in blood sugar. Lactose in regular milk is absorbed slowly, as it requires enzymatic breakdown. Glucose and galactose from lactose-free milk — are already broken down and quickly enter the bloodstream, causing a spike in glucose.
2. Increased insulin load. Rapid sugars require a quick response from the pancreas, which may be undesirable in prediabetes, metabolic syndrome, and insulin resistance.
3. Glycosylation of proteins. Frequent consumption of high glycemic index products increases the formation of AGE products (advanced glycation end-products), which affects tissue aging and inflammation.

Thus, lactose-free milk:

• Formally contains no lactose, but contains glucose and galactose
• May cause faster spikes in blood sugar than whole milk
• Sometimes contains added sugar, especially in flavored varieties

Therefore, for people with insulin resistance, diabetes, or excess weight, it may be less preferable than regular milk if there is no true lactose intolerance.