Tea with the meal
The only dial aimed specifically at ferritin. Polyphenols from black and green tea inhibit iron absorption from the same meal.
Order of magnitude
A cup of black or green tea with the iron-rich meal rather than after it.
With a high ferritin that is desirable. Anyone with a value at the bottom of the target range should do the opposite and move the tea between meals. Same mechanism, opposite sign. Hurrell 1999 (meal-time absorption) was not opened in this batch. No chronic ferritin size (G-D3); the percentage stays a placeholder.
Effects in detail
Each row is a directed edge from our database, with range, latency, evidence grade and the condition under which it applies at all.
| Marker | Effect | Latency | Mode of action | Outcome | Evidence | Condition | Sources |
|---|
What this measure costs
Counteracting effects of the same measure.
No counteracting effect is on file for this measure. That does not mean there is none, only that we found no defensible edge.
Moves without implying progress
Informational or no established effect: the marker moves or was checked, and that is not progress.
| Marker | Effect | Latency | Mode of action | Outcome | Evidence | Condition | Sources |
|---|---|---|---|---|---|---|---|
| Ferritin | moves, and does not count. Lowers Direction known, size not established The edge only applies from a ferritin in the upper range, because inhibiting iron absorption is a disadvantage rather than an advantage when the store is low. | 12–26 weeks | postprandial | unclear | Evidence grade C | Ferritin at or above 150 ng/mL |
Sources
Full details of every study the rows above rely on.
Prediction of dietary iron absorption: an algorithm for calculating absorption and bioavailability of dietary iron
Hallberg and Hulthén · American Journal of Clinical Nutrition · 2000 · Review
Inhibition of non-haem iron absorption in man by polyphenolic-containing beverages
Hurrell et al. · British Journal of Nutrition · 1999 · Randomised trial