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Ellagitannins

Overview

Ellagitannins are hydrolysable tannins. Hydrolysis releases ellagic acid, which some gut communities convert toward urolithins. Urolithin A is a downstream metabolite. A food that supplies ellagitannins does not contain urolithin A, and the tannin class is not the free acid.

The human comparison used pomegranate juice, a matrix that can provide ellagitannins, against direct urolithin A. Juice exposure to urolithin A varied between people, while direct administration bypassed conversion and raised exposure [1]. That juice is not proof that every ellagitannin, or every ellagitannin-containing food, converts to the same degree [1]. Final metabolite generation varies with the microbial community.

Dietary Origin

The dietary relationship is precursor supply: ellagitannins can be hydrolysed to ellagic acid, which is then a microbial substrate. Pomegranate juice is the food matrix in the human comparison [1]. It is not an isolated ellagitannin, and it is not urolithin A. Direct urolithin A supplementation is a different exposure and does not test tannin hydrolysis [1]. No food page is tagged as containing urolithin A because of its ellagitannins.

Research Spotlights & Evidence Checks

🔎 Evidence Check · whole-food

Does pomegranate juice show that every ellagitannin yields urolithin A?

No. The juice produced variable urolithin A exposure. Direct urolithin A bypassed conversion. One juice matrix is not every ellagitannin [1].

Read the evidence

Urolithin A from the juice depended on the person’s microbial conversion, and giving urolithin A itself removed that dependency [1]. Hydrolysis of ellagitannins can release ellagic acid upstream of that route. The study does not measure each ellagitannin separately, so equivalence across the class is not established [1].

Recipes

no recipes found (no foods contain this substance)

Foods

no foods found

Biological Regulatory Systems

Biological Regulatory System	Evidence-qualified relationship	Evidence
Gut-Brain Axis & Enteric Nervous System (BRS5)	Ellagitannins are the upstream substrate class in polyphenol biotransformation. Hydrolysis releases ellagic acid. The human comparison used pomegranate juice, not every ellagitannin.	[1]

References

[1] Singh et al. (2022). Direct supplementation with Urolithin A overcomes limitations of dietary exposure and gut microbiome variability in healthy adults to achieve consistent levels across the population. Pomegranate juice, an ellagitannin-containing matrix, produced variable urolithin A exposure. Direct urolithin A bypassed conversion. The juice does not establish equivalent conversion from every ellagitannin.