How many essential amino acids must be obtained through diet?

The correct answer is nine essential amino acids. Essential amino acids are those that the body cannot produce on its own and must be obtained through food sources. These amino acids play crucial roles in various physiological functions, including protein synthesis, tissue repair, and the production of hormones and enzymes.

The nine essential amino acids are histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. Consuming a balanced diet that includes complete protein sources—such as meat, fish, dairy, eggs, and certain plant-based foods like quinoa and soy—ensures that the body receives all nine essential amino acids necessary for optimal health and performance.