Clinical Nutritionist Practice Test 2026 - Free Practice Questions and Study Guide

A complete protein is defined as one that contains all nine essential amino acids in sufficient quantities to meet human nutritional requirements. Essential amino acids are those that the body cannot synthesize on its own and must be obtained through diet. They play a crucial role in various bodily functions, including tissue repair, muscle synthesis, and overall health.

Proteins that are considered complete are typically found in animal sources, such as meat, poultry, fish, eggs, and dairy products. However, some plant-based sources, such as quinoa and soy, also qualify as complete proteins. This characteristic distinguishes complete proteins from incomplete proteins, which lack one or more essential amino acids.

While aspects such as digestibility, calorie content, or being plant-based can contribute to the overall quality of a protein source, they do not define its completeness. Therefore, recognizing that a complete protein contains all essential amino acids is fundamental in nutritional science, allowing for better meal planning and dietary choices.