What defines complete proteins?

Complete proteins are defined by their ability to provide all nine essential amino acids that the human body cannot synthesize on its own. These essential amino acids must be obtained through diet to support various bodily functions, including muscle repair, enzyme production, and overall growth and maintenance of tissues. Sources of complete proteins include animal-based foods such as meat, fish, dairy products, and eggs, as well as some plant-based sources like quinoa and soy.

The other options do not accurately describe complete proteins. Protein that lacks essential amino acids would be classified as an incomplete protein, which is typically found in many plant sources. Proteins that are high in carbohydrates or derived solely from plant sources may not necessarily provide all essential amino acids, making them insufficient as complete proteins. Understanding these distinctions is crucial for formulating balanced diets that meet nutritional needs.