[Science Debunked] Is Galactose Really That Scary? Behind the Doctor's Warning, the Real Metabolic Mechanism Your Body Needs to

Galactose is primarily metabolized in the human body through the 'Leloir pathway'. When we drink milk or consume dairy products, the lactose within them is broken down into glucose and galactose by lactase in the small intestine. Galactose then enters the liver via the portal system, which is its main metabolic site. The entire conversion mechanism involves the following three core steps: 1. Phosphorylation: Galactose is first catalyzed by 'galactose kinase (GALK)', consuming an ATP molecule, to convert into galactose-1-phosphate. 2. Transfer Reaction: Next, under the action of 'galactose-1-phosphate uridylyltransferase (GALT)', it exchanges a group with UDP-glucose to produce UDP-galactose and glucose-1-phosphate. 3. Isomerization: Finally, UDP-galactose is catalyzed by 'UDP-glucose-4-epimerase (GALE)' to convert back into UDP-glucose, entering the next cycle. The resulting glucose-1-phosphate is converted to glucose-6-phosphate, which enters glycolysis to be transformed into energy or synthesized into glycogen for storage. The liver in healthy adults can efficiently process galactose. Only in cases of congenital deficiency of related metabolic enzymes (like galactosemia) or 'extremely excessive' intake might galactose accumulate in the body due to insufficient metabolism, leading to health risks such as cataracts or tissue aging.