The organ responsible for the majority of nutrient absorption in the digestive system is the small intestine. This long, coiled organ is specifically designed to maximize absorption through its large surface area, which is enhanced by villi and microvilli. Nutrients from digested food, such as carbohydrates, proteins, and fats, are absorbed into the bloodstream here. The efficient functioning of the small intestine is essential for maintaining overall health and providing energy to the body.