Ellagic acid
Overview
Ellagic acid is a polyphenol released when ellagitannins are hydrolysed. It is the compound some gut bacteria convert toward urolithins. Urolithin A is a downstream metabolite, not ellagic acid, and a food that supplies ellagic acid does not contain urolithin A.
Two human intestinal Gordonibacter species converted ellagic acid into intermediate urolithins in culture. They did not establish complete urolithin A production by those two species alone [1]. In healthy adults, urolithin A exposure from pomegranate juice varied, while direct urolithin A administration bypassed conversion [2]. Conversion depends on the microbial community and may stop at intermediates. It does not imply that everyone converts ellagic acid, or that ellagic acid itself increased mitochondrial function [1,2].
Dietary Origin
Ellagic acid can occur in foods after ellagitannins hydrolyse, and it is the substrate given to the Gordonibacter cultures [1]. Pomegranate juice in the human comparison is a food matrix that can yield variable urolithin A, not a measured dose of isolated ellagic acid [2]. Direct urolithin A supplementation skips the conversion and is evidence about the metabolite, not about ellagic acid [2]. No food page is given a contains link that would treat juice, ellagic acid, and urolithin A as the same substance.
Research Spotlights & Evidence Checks
Recipes
Foods
Biological Regulatory Systems
| Biological Regulatory System | Evidence-qualified relationship | Evidence |
|---|---|---|
| Gut-Brain Axis & Enteric Nervous System (BRS5) | Ellagic acid is the immediate microbial substrate in polyphenol biotransformation. Conversion is community-dependent and may stop at intermediates. | [1,2] |
References
[1] Selma et al. (2014). Description of urolithin production capacity from ellagic acid of two human intestinal Gordonibacter species. Two Gordonibacter species converted ellagic acid into intermediate urolithins. They did not establish complete urolithin A production by those species alone.
[2] 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 produced variable urolithin A exposure. Direct urolithin A bypassed conversion. A juice matrix is not isolated ellagic acid, and the supplement does not test microbial conversion.