Protein

Protein is an essential nutrient required for human health. Fresh foods provide different types and amounts of it. Animal-based sources such as red meat, poultry, seafood, milk, and eggs contain high-quality protein and all nine amino acids needed for growth and maintenance. Many plant-based sources, such as cereal grains, legumes, nuts, and seeds, lack certain amino acids, but combining sources can improve protein quality. For example, consuming rice and beans or peanut butter on whole-wheat bread provides protein comparable to a beef hamburger patty.

Why do we need amino acids? Proteins are the basic building blocks of the body. They comprise amino acids essential for protein synthesis and degradation. For example, we require synthesis for new muscle fiber. Also, we need degradation to provide energy, nitrogen, and carbon skeletons for metabolism. Protein provides essential amino acids that you cannot synthesize from other compounds; therefore, your diet must provide them. It is essential for synthesis/degradation, affecting body composition. For example, lean tissue mass increases when synthesis exceeds degradation and decreases when degradation exceeds synthesis.

We base nutritional needs on body weight and health status. Individuals who exercise regularly have more significant needs than non-exercisers. Depending upon the activity’s type, intensity, and duration, requirements can range from 3 to over 20 percent of total daily calories. The RDA for exercisers is 0.5 g protein per kg body weight per day or 10 to 35 percent of total daily calories. For weight-loss diets, intakes of up to 1.5 grams per kg body weight may be beneficial for limiting lean tissue loss and maintaining metabolism. We do not recommend an intake of fewer than 0.8 grams per kg body weight per day since protein is essential for physical and mental well-being.  Depending upon their intake, requirements for these individuals can range from 0.8 to 1.0 g protein per kg of body weight per day.