Tannins (iron brake)
What slows things down
The same polyphenols as the flavanol family, seen from the other side: they bind to the plant iron of the meal.
Effects
Tea and coffee drunk with a meal hold back iron from plants: a cup of tea cut it by more than half in trials, coffee by about a third. Iron from meat, on the other hand, is hardly affected.
Tannins bind to non-heme iron, that of plants and eggs, in complexes the gut does not absorb. In trials, a cup of tea drunk with a meal reduced the iron absorbed by 60% or more, a cup of coffee by about 40% (Morck et al., 1983; Hurrell et al., 1999). The heme iron of meat and fish is barely touched.
By sex and age: women before menopause, teenage girls and people who eat no meat are the most concerned, their iron needs being high or their sources mainly plant-based.
Sources: Morck et al., AJCN, 1983 · Hurrell et al., Br J Nutr, 1999
The remedy
Nothing to remove: just drink tea and coffee apart from meals, and add vitamin C to the meal itself. The molecule remains beneficial otherwise.
Where to find it (15)
- Cocoa / very dark chocolate
- Coffee
- Cranberry
- Grape
- Matcha
- Persimmon
- Pomegranate
- Pu-erh tea
- Quince
- Red sorghum
- Red wine
- Roasted chicory
- Sloe
- Strawberry tree fruit
- Tea (black, green, oolong)