What element do proteins uniquely contain that lipids and carbohydrates do not?

Proteins are unique among the macronutrients—proteins, lipids, and carbohydrates—in that they contain nitrogen as a fundamental component of their structure. This nitrogen is found in the amino acids that make up proteins. Amino acids are the building blocks of proteins, and each amino acid has an amino group (-NH2) that contains nitrogen.

In contrast, lipids and carbohydrates are typically composed of carbon, hydrogen, and oxygen, but do not contain nitrogen in their basic structures. The presence of nitrogen in proteins plays a crucial role in forming the peptide bonds that link amino acids together, influencing protein structure and function. Understanding this distinctive feature of proteins is essential for grasping concepts related to nutrition and biochemistry, as it underscores the diverse roles that different macronutrients play in biological processes.