Final answer:
Amino acids are a true source of nitrogen for the body. They are used for synthesizing proteins and other nitrogen-containing molecules and can serve as an energy source. Excess amino acids are not stored but are instead metabolized, with nitrogen excreted as urea.
Step-by-step explanation:
Amino acids do indeed serve as a source of nitrogen for the human body; this statement is true. After being hydrolyzed from dietary proteins, amino acids contribute to the body's amino acid pool. This pool is critical for various metabolic processes, including the synthesis of proteins and other nitrogen-containing compounds such as DNA bases, neurotransmitters, and hormones. Amino acids may also be used as a source of energy, particularly during periods of fasting or starvation when carbohydrates and fats are not available. However, it's important to note that the body cannot store amino acids in the long term; any excess amino acids are degraded, with the nitrogen byproduct excreted as urea in the urine.
There are essential amino acids which the body cannot synthesize and must be obtained from the diet, while others are non-essential because the body can synthesize them. The essential amino acids are crucial for protein synthesis, body repair, and growth, especially in infants and children.