"Messengers" of cellular communication: Acting like the body's couriers, they deliver instructions to cells—such as telling skin cells it is time to produce collagen or signaling immune cells to prepare for combat.
Rapidly absorbed "nutrient packages": Small-molecule peptides do not require complex digestion; they are absorbed directly by the intestines in their intact form and quickly converted into the energy and repair materials the body needs.
"Regulating valves" for physiological balance: Many hormones (such as insulin) and neurotransmitters are essentially peptides, precisely controlling our blood sugar, sleep, mood, and immune function.