Based on the Dietary Reference Intake, proteins should make up what percentage of an adult’s daily caloric intake?

Choice A reason: Skinless chicken breast is a lean protein, providing about 26 grams per 3-ounce serving with low saturated fat. It supports muscle maintenance without increasing cholesterol levels, making it a healthy choice for frequent consumption, not one to reduce, as it aligns with heart-healthy dietary goals.

Choice B reason: Fried shrimp is high in saturated fats due to frying, elevating low-density lipoprotein (LDL) cholesterol and heart disease risk. Despite providing about 20 grams of protein per serving, its preparation makes it less healthy, warranting less frequent consumption to minimize cardiovascular risks in a balanced diet.

Choice C reason: Baked codfish is a lean protein, offering about 20 grams per 3-ounce serving with omega-3 fatty acids that reduce heart disease risk. It is a healthy choice for frequent consumption, supporting muscle maintenance and cardiovascular health, not a protein to reduce in the diet.

Choice D reason: Tofu, a plant-based complete protein, provides about 10 grams per 1/2 cup with low saturated fat. It supports heart health and muscle maintenance, making it a healthy choice for frequent consumption, especially for vegetarians, and not a protein to reduce in a balanced diet.

Choice A reason: Complex proteins is not a standard term in nutritional science. Proteins are classified as complete or incomplete based on essential amino acid profiles. Plant sources like grains and nuts lack one or more essential amino acids, making this an incorrect classification for such proteins.

Choice B reason: Incomplete proteins, such as those from grains, nuts, and most legumes, lack one or more essential amino acids required for human protein synthesis. Combining these with complementary plant sources (e.g., rice and beans) can form complete proteins, meeting dietary needs for growth and repair.

Choice C reason: Complete proteins contain all nine essential amino acids in adequate amounts, typically found in animal sources like meat or soy. Most plant sources, excluding soybeans, are incomplete, as they are deficient in certain amino acids, making this an incorrect choice.

Choice D reason: Simple proteins is a biochemical term referring to proteins composed solely of amino acids, not a nutritional classification. It does not describe the amino acid profile or dietary role of plant-based proteins, which are typically incomplete, making this an incorrect option.