Nutrients are mainly absorbed in:

Proteins, carbohydrates, fats and other nutritive substances like vitamins, and minerals are absorbed mostly in small intestine. In the small intestine, secondary active transport of Na+ is important in bringing about absorption of glucose, some amino acids, and other substances such as bile acids. Reference: GUYTON AND HALL TEXTBOOK OF MEDICAL PHYSIOLOGY, THIRTEENTH EDITION(INTERNATIONAL EDITION ) page no 464