Amino Acids: Peptide Bond vs. Free Form

I was just reading about Dorian Yates’ diets. He mentions supplementing with “Peptide Bond Amino Acids”.

I know that many supps on the market today have various free form amino acids.

What is the benefit(s), if any, of one over the other?

Well, a peptide bond is really just the chemical bond that ties two amino acids together. A protein consists of long chains of amino acids, called polypetides, that form a 3 dimensional, folded structure, through means of different attractions between the molecules. The folded structure is important for proteins your body produces, like enzymes.

However, when the body digests protein, the folded structure is broken first, and then the peptide bonds as well, for easier uptake into the bloodstream and to make single amino acids available so the body can use them as building blocks. Free form amino acids are, like the name says, “free” of peptide bonds, so that digestion and uptake is much easier and you can deliver the exact amino acids the body needs most to build muscle (not all amino acids are involved in muscle, or structural, proteins).

My best guess to why Yates mentions peptide bond aminos is that the refining process has gotten much better since he wrote that, and also that it is better understood which specific amino acids, and in which ratio, an athlete/bodybuilder needs.

To sum up: free form aminos have much higher bioavailability, meaning faster and more complete uptake, whereas peptide bond amino acids are closer to what you find in “real” food like meat or eggs and may be beneficial before sleeping because of slower uptake, although the last is just a guess on my part.

While it seems counter intuitive, I thought peptides are often actually up-taken faster (than free form aminos) due to specific peptide receptors in the gut. At least this is how it works in general and there may be some aminos that absorb faster than a peptide.

For example, this is why a protein like casein hydrolysate is much better than those liquid EAA drinks (twinlab) that contain a specific amount of each amino acid, even if gram for gram each product contains the same exact amount of protein, and even the same amount of each amino – the peptide bonds are responsible for the fast uptake… the body is able to recognize them in that form and use them for anabolism of lean muscle more readily.

I think Dorian talked about amino-supps where the amino acids are all available in form of di- or tripeptides.

As for absobtion. There are diffrent ways of amino acid absorbtion in the intestine. There are receptors (transportes) for single free form amino acids as well as recepotors for peptides.

For some combination of AA, peptide-uptake is indeed faster than the uptake of the same amino acids if consumed as single free form AA.
This is not true for all di-peptides.

Usually, the fastest uptake is achieved by a combination of both free form amino acids as well as certain (no all possible) di- and tri-peptides.

I wrote some posts with more details in Thib’s forum (Questions about amino acid pulsing).

Partially hydrolized casein offers the best profile of ffAA and the relevant peptides, which makes this the “fasted” protein available.