Both amino acids and polyphenols are popular supplements, but they differ significantly in their absorption, metabolism, ability to reach target cells, and overall impact on health optimization. I have had a question on my mind for quite some time now. How to get the expected and real biological benefits from my supplementation? Amino acids and other classes of substances are more predictable.
I get really noticeable effects from amino acids like Taurine, and citrulline. And others on this forum present N1s of the benefits from GlyNac. There are amino acid derivatives like creatine and TMG. Both have a reliable absorption and have a known capacity to reach target tissues. When it comes to polyphenols theire effect are more difficult to predict. But I still favor the daily use of curcumin and intermittent use of fisetin, EGCG and quercetin.
My main point is that I think it is time for me to reduce my focus on polyphenols and focus more on amino acids and other classes of substances. What do the forum think?
Absorption
Amino acids are absorbed efficiently in the small intestine through specific transporters, allowing rapid entry into the bloodstream and are immediately available. In contrast, polyphenols generally have low bioavailability. Many polyphenols are bound to sugars or plant matrices and require enzymatic release. They are partially absorbed in the small intestine, but a significant portion reaches the colon, where gut microbiota metabolize them before absorption of their metabolites. So what we get from polyphenols are metabolites.
Metabolism
Once absorbed, amino acids are primarily metabolized in the liver and muscle tissues. Certain amino acids, like branched-chain amino acids (BCAAs), activate key signaling pathways such as mTOR. immune responses, and energy metabolism. Polyphenols undergo extensive metabolism in the intestine and liver, including phase I and phase II reactions (e.g., glucuronidation, sulfation). It is often the polyphenol metabolites—not the original compounds—that exert biological effects.
Capacity to Reach Target Tissues
Amino acids circulate freely in the bloodstream and are readily taken up by various tissues, including muscle, liver, and immune cells. Polyphenols and their metabolites circulate at much lower concentrations and may have limited direct uptake by tissues. Their health effects can be local (within the gut) or systemic, mediated by metabolites influencing cells such as vascular endothelial cells.
Stability
Amino acids are chemically stable throughout digestion and do not require special release mechanisms. Polyphenols, however, are often unstable and susceptible to degradation by enzymes like polyphenol oxidase and oxidation processes. Their bioaccessibility depends on food processing, formulation, and protection from degradation, which can affect how much is available for absorption.
In summary, amino acid supplements offer high and predictable absorption, stable delivery, and direct metabolic roles in target tissues. Polyphenols provide beneficial antioxidant and anti-inflammatory effects mostly through their metabolites, but their lower and variable bioavailability, plus dependence on gut microbiota, make their supplementation outcomes more variable.