Enterohepatic recirculation is a loop in which a compound or one of its metabolites is excreted into bile, delivered to the small intestine, and reabsorbed back into circulation rather than leaving the body on the first pass.
Why it matters for logging
Recirculation can stretch how long a compound stays active, which complicates how a journal links a dose to an observed effect. A reading taken many hours after intake may still be sampling material from a second or third pass, not a clean post-dose baseline. Without that context, exposure looks shorter than it is.
What it changes about exposure
The loop can shift the curve in several ways.
- Effective half-life lengthens because the body re-encounters the same material.
- Late secondary peaks can appear after intake, sometimes near a meal that triggers bile release.
- Stacks with multiple recycled compounds can interact in ways simple dose math does not catch.
Food and stack interactions
Bile flow rises with fat-containing meals, which can change a recirculation peak after intake. A compound that binds bile components in the gut may shorten the loop and reduce later exposure. When stacking oral products, this can make the effective exposure of a recycled compound harder to interpret. Reviewing overlap between compounds with shared elimination paths helps surface these effects.
Relation to dosing frequency
For recycled compounds, dosing frequency is harder to interpret from the first peak alone because later exposure can still be part of the same loop.
Practical action step
For compounds with known recirculation behavior, keep route, food context, and logging windows consistent before judging whether a later reading belongs to a new dose or residual exposure.
Uncertainty and limits
- Recirculation magnitude varies widely by compound, gut transit, and microbiome state.
- Many labels do not describe second-peak effects in real routines.
Cross-site references
How this appears in Unfair
Unfair flags compounds with notable recirculation behavior when comparing journal entries, and widens attribution windows so a late effect is not blamed on an unrelated recent dose.
Clinical safety note
If a compound with strong recirculation produces stacking side effects, pause changes and consult a clinician before changing amount or shortening cycles.