What dietary substrate is broken down into glucose and galactose by intestinal enzymes?

The correct answer is that lactose is the dietary substrate broken down into glucose and galactose by intestinal enzymes. Lactose is a disaccharide sugar composed of two monosaccharides: glucose and galactose. It is primarily found in milk and dairy products.

In the small intestine, the enzyme lactase plays a pivotal role in the digestion of lactose. Lactase hydrolyzes lactose into its component sugars, glucose and galactose, ensuring they can be absorbed through the intestinal wall into the bloodstream. This process is crucial for individuals, especially infants, who rely on milk as a primary energy source.

Understanding this process is vital in the context of lactose intolerance, where individuals have insufficient levels of lactase, leading to gastrointestinal symptoms when consuming lactose-containing foods.

The other options represent different sugars that undergo different metabolic pathways: fructose is broken down into glucose and fat by enzymes in the liver; maltose is a disaccharide broken down into two glucose molecules; and sucrose is split into glucose and fructose. Each of these substrates has specific enzymes responsible for their digestion, distinct from the action of lactase on lactose.