What does the term complete protein mean?

• A. Contains all essential amino acids in sufficient amounts
• B. Contains only non-essential amino acids
• C. Provides all carbohydrates
• D. Is derived from animals only

Answer: (A)

Complete protein means it supplies all essential amino acids in adequate amounts. Essential amino acids are those the body cannot synthesize in sufficient quantities, so they must come from the diet. A protein that includes these amino acids in the right proportions supports growth and maintenance without needing to rely on combining foods to cover gaps. Most animal foods are complete, and some plant foods, such as soy and quinoa, are complete as well. The other choices don’t fit because they describe non-essential amino acids, carbohydrates, or sources that aren’t strictly limited to animals.