Final answer:
The percentage of true protein that is absorbed and available for bodily functions is around 95 to 98 percent in the small intestine, where it is digested and absorbed as amino acids.
Step-by-step explanation:
The percentage of true protein absorbed from the intestinal tract available for productive bodily functions varies, with high-quality proteins having close to 100% biological value, meaning that they are completely digested and absorbed.
Most proteins are absorbed as their breakdown products, predominantly amino acids, after being digested in the small intestine. Specifically, 95 to 98 percent of protein is digested and absorbed in the small intestine.
Additionally, protein turnover in the human body involves the resynthesis of new proteins from degraded ones, with 75-80% of amino acids being reused for this process, contributing to the overall efficiency of protein utilization in the body.