Polyvinylpolypyrrolidone.

Insoluble polyvinylpolypyrrolidone binds the phenolic hydroxyl groups of tannins by hydrogen bonding to its amide carbonyls, which is exactly how it is used to strip tannins from beverages. In a capsule it can lower the amount of free tannin available for absorption.

PVPP is the standard industrial adsorbent for polyphenols because its pyrrolidone carbonyl accepts hydrogen bonds from phenolic hydroxyls. Co-formulating it with a polyphenol active works against that active reaching the gut wall in free form.

Proanthocyanidins are condensed tannins with many phenolic hydroxyls, the highest affinity class for PVPP binding. Putting the two in one tablet reduces the free OPC fraction.

Grape seed extract is dominated by oligomeric proanthocyanidins, which PVPP adsorbs strongly through hydrogen bonding. Formulating them together lowers the polyphenol load actually delivered.

Galloylated catechins such as EGCG carry the polyphenol pattern PVPP was designed to capture. The binding is the same one used to remove haze-forming polyphenols in brewing, so co-formulation works against the catechin dose.

Catechin monomers bind PVPP through their ortho-dihydroxy phenol groups, though less tightly than the larger polymers. Enough is retained on the polymer to matter in a shared dose.

Hydrolysable tannins carry a dense field of galloyl hydroxyls and adsorb readily to PVPP. That removal is the intended industrial use of the polymer and it does not stop inside a capsule.

Quercetin's catechol ring hydrogen bonds to the pyrrolidone carbonyl in the same way other flavonoids do, so some of the dose stays associated with the insoluble polymer. The effect is weaker than with polymeric tannins but is the same mechanism.

Polyvinylpolypyrrolidone is used industrially to strip polyphenols out of beverages precisely because it binds phenolic hydroxyl groups through hydrogen bonding. Curcuminoids are polyphenols and carry those groups. In a dry tablet the two are in contact only briefly, but the affinity is real and is worth knowing when a polyphenol is co-formulated in a wet or liquid system.

Resveratrol is a stilbene polyphenol with free hydroxyl groups of the type crospovidone binds. Wine and juice processing exploits exactly that to remove such compounds. The interaction matters in solution far more than in a compressed dry tablet.

Pine bark extract is dominated by procyanidins, the oligomeric polyphenols that crospovidone binds most avidly. That affinity is the entire basis for the polymer's use in haze removal. Formulators combining the two in a liquid or suspension should account for it.

Bilberry's anthocyanins and associated tannins carry the phenolic hydroxyls that crospovidone hydrogen-bonds. Juice processors use the polymer to remove colour and haze bodies for that reason. In a dry capsule the contact time is short, so the practical impact depends heavily on the format.

Rutin retains free hydroxyls on its flavonoid core despite the sugar attachment, so it falls in the class crospovidone binds. Binding is stronger for larger polyphenols than for simple glycosides. The row records the direction of the interaction, not its magnitude in any specific product.

Luteolin's catechol arrangement gives it the adjacent hydroxyl pairs that bind most tightly to pyrrolidone carbonyls. This is the same chemistry that makes the polymer useful for removing haze from beverages. Relevant to liquid formats far more than to tablets.

Apigenin carries fewer hydroxyls than luteolin and therefore binds the polymer less strongly, but it sits in the same interaction class. In a dry tablet the two meet only for the seconds of disintegration. The note is for wet processing and suspensions.

Pterostilbene's two methoxy groups replace hydroxyls that would otherwise hydrogen-bond to the polymer, so its affinity for crospovidone is lower than resveratrol's. That structural difference is the reason the two stilbenes behave differently in the same formulation. It is a useful contrast rather than a problem to solve.

Silymarin is a mixture of flavonolignans carrying the phenolic groups the polymer binds. It is also poorly water-soluble, so it is frequently paired with disintegrants in solid dosage forms. Both facts are worth holding at once when the two appear on the same label.

Elderberry's colour and much of its characterised chemistry are anthocyanins, polyphenols the polymer binds and that juice processors sometimes deliberately remove with it. In supplements the polymer is present at a small percentage as a disintegrant, so the contact is limited. The interaction is directional and format-dependent.

Tannins and other polyphenols chelate non-heme iron and reduce its absorption, which is settled nutrition pharmacology. A polymer that binds those same polyphenols changes how much free polyphenol is available to do so. Whether this measurably affects iron uptake in a supplement has not been studied, so the confidence sits at the bottom band.