High milk consumption, defined as three or more glasses per day, is associated with a 93% higher risk of all-cause mortality in women and a 10% higher risk in men over a follow-up period of 11 to 22 years, with high lactose intake potentially contributing to adverse health outcomes independent of other dietary factors.

When a person drinks a lot of milk, the sugar in it breaks down into a compound called D-galactose. This compound overwhelms the body's ability to process it, causing cells to produce too many harmful molecules that damage fats, proteins, and DNA. This damage triggers a persistent low-level inflammatory response throughout the body. Over time, this constant stress wears down bones, muscles, and organs, making the body age faster and increasing the chance of death.