Which of the following best describes essential amino acids?

Essential amino acids are those that the body cannot synthesize on its own, meaning they must be obtained from dietary sources. This makes them critical for various physiological functions, including protein synthesis, tissue repair, and the production of neurotransmitters and hormones. Since the body cannot produce essential amino acids, they must be consumed through food sources such as meat, dairy, and certain plant-based proteins.

The other options do not accurately describe essential amino acids. While some amino acids can be produced by the body, essential amino acids specifically cannot be, hence the first option is not correct. The assertion that essential amino acids are exclusively found in animal proteins is misleading, as many plant proteins also contain these essential amino acids, albeit sometimes in lesser amounts or in lower diversity. The notion that essential amino acids are harmful is inaccurate; rather, they are vital for health and well-being.