Final answer:
A positive protein balance is true when the intake of proteins exceeds the losses, reflected in a positive nitrogen balance. Protein turnover is a continuous process of synthesis and degradation for maintaining health. Biological value indicates a protein's efficiency in maintaining nitrogen balance, with animal proteins usually having higher values.
Step-by-step explanation:
True, a positive protein balance occurs when protein intake exceeds daily protein losses. This implies that the intake of nitrogen, which is a key component of amino acids in proteins, is greater than the nitrogen expelled through urine and feces, a condition known as positive nitrogen balance. The bodily state of nitrogen balance is essential for growth, healing, and maintaining muscle mass.
Proteins are constantly being turned over in the body in a process known as protein turnover, where synthesis and degradation of proteins are balanced. This turnover ensures that older proteins are replaced with new ones for proper bodily function.
A diet with sufficient energy but lacking in protein can indeed lead to undernutrition, specifically kwashiorkor, characterized by a distended belly among other symptoms. It is related to fluid retention in the abdominal area rather than simply an expansion of the stomach due to lack of food.
Biological value is another key concept, identifying how efficiently a protein source can meet the body's nitrogen balance requirements. Animal proteins generally have a higher biological value than plant proteins, with sources like egg and milk nearing a biological value of 100%, meaning they're highly efficient at replacing the nitrogen lost in urine.