What are 'acid stable' amino acids?

Question

I tend to see terms `amino acid`, `acid stable amino acid`, and `free amino acids` used often in the field of nutrition, but they are sometimes used interchangeably which confuses me. I know that:- **amino acid** is a general term to describe organic compounds that encompass both essential and non-essential amino acids.- **free amino acids** is a general term for amino acids that are not broken down from a protein source; instead it exists in its original form 'freely'.- **acid stable amino acid** ... no ideaIs that right (correct me if I'm wrong)? What is the larger relationship amongst all three terms? Would consuming a **free amino acid** be better than one from a protein, or from an **acid stable amino acid**? Why would one choose to consume a particular class of amino acids over another?

Answer 1

Anytime that you see the term amino acid you should think of the word protein, peptide, or enzyme. Amino acids are the building block of proteins. In other words, think of amino acids as beads on a necklace, the more beads you have strung on the necklace the longer the necklace "protein" will be. When you think of free amino acids, these are one amino acid or several smaller amino acid chains that are broken down by the stomach primarily by peptidase from a larger protein and transported throughout the body. Think if I cut the necklace into 4 parts or took 1 bead off the necklace these example would be free amino acids. Peptidase is found in the stomach which and can have a pH as low as 1.5-3.5 and helps to break down proteins that are consumed into the body.

Of the 20 standard amino acids, nine are called essential amino acids because the human body cannot synthesize, so they must be consumed. The other 11 amino acids are non-essential and can be formed by the body breaking them down and re-synthesising them into the correct forms. Different food contain different essential amino acids. Most time if you eat a balanced diet you will receive all the necessary essential amino acids. However, you can supplement an isolated form of these amino acids through dietary supplements.