This is a topic so large it could take stacks of text books (and it does!) and many semesters in college and years of research afterward, so an exhaustive review is both beyond the scope of this article and my brain!
There’s a few key areas however I plan to address in this article people will find helpful to making smart decisions the over hyped ads for protein, amino acids, and peptides don’t cover. For the most part, I recommend whole protein sources, such as whey, eggs, lean meats, fish etc. in terms of dietary protein* intakes, but some individual amino acids can be of benefit in specific applications. Those applications may be sports performance related, general health, or medical, but I’m getting ahead of myself.
Back In The Day…
Back in the day when I was taking my first nutrition courses and reading what research existed - right after the Pleistocene era – the mantra of nutrition was that digested proteins were broken down into individual amino acids during digestion and absorbed, and that was that. As with virtually all overly simplified models generated from the early research examining human nutrition and physiology, it was wrong. To this day however, there are still those who believe it, but I digress. However, most know that ingested proteins are broken down primarily into small peptides and individual amino acids. The fact is, to this day, human digestion, absorption, and utilization of nutrients we ingest is still being elucidated with more discoveries being made than most people realize or appreciate. It’s amazing to me however the number of people – some educated enough in the sciences to know better – who think digestion, absorption, and utilization of the food we eat can be summarized as “it get’s dumped into the acid in your stomach, then absorbed via voodoo, the end.” Human digestion, absorption, and utilization of the nutrients we ingest, is an incredibly complex process, that as previously mentioned, still being elucidated. If you want to get a glimpse of how complex, the Encyclopedia Britannica site has a nice write up on that, and remember: digestion, absorption, and utilization of protein is but one very small aspect of it.
As mentioned previously, there are benefits and potentially unique effects to using individual amino acids, but studies indicate peptides are better absorbed and or utilized than individual amino acids. What that suggests is, even if the goal is to derive benefits from a singe amino acid (e.g., Leucine, Glutamine, etc.), it’s likely best to get it in peptide form. For example, instead of taking L-leucine alone as the free amino acid, to increase intakes of L-leucine, ingesting a leucine rich peptide is likely to be the superior approach. The science and understanding of the value of peptides in human nutrition, be it for health, performance, increased muscle mass, etc., is an evolving area of research yielding useful findings, and still in it’s early stages in fact. Because this is such a wide-open and extensive topic, I’m going to stay focused on a few key issues, such as the value of using individual amino acids or “free” amino acids vs. peptides even if the goal is to increase levels of a specific amino acid.