Punicalagin in pomegranate blocks TMA production in colon model
What it found
In lab tests using human stool samples, punicalagin, a pomegranate compound, almost completely stopped gut bacteria from making trimethylamine (TMA) from L-carnitine.
Other pomegranate compounds tested did not have this effect.
What they found
Animal and lab studies
Punicalagin blocks TMA
Punicalagin almost completely blocked TMA production from L-carnitine. At 48 hours, only 0.4% of the initial L-carnitine became TMA, compared to 39.2% in the control.
Other compounds no effect
Punicalin, ellagic acid, gallic acid, urolithin A, urolithin B, and gum Arabic did not significantly reduce TMA production.
Urolithins may increase TMA
Urolithin A significantly increased TMA concentrations at 28 hours compared to the control. Urolithin B showed a non-significant trend in the same direction.
Whole extract lowers pH
The whole pomegranate extract caused a large drop in pH, to 4.9 by 48 hours, which completely stopped L-carnitine metabolism. This pH drop was likely due to carbohydrates in the extract.
What the authors conclude
- They conclude that punicalagin is the principal inhibitor of microbial L-carnitine metabolism in the pomegranate extract.
- They say punicalagin is a promising candidate for dietary modulation of the TMA/TMAO pathway, with potential implications for reducing cardiovascular disease risk.
- They call for further studies to explore the mechanisms and to test if pomegranate extract or punicalagin can inhibit circulating TMAO levels in a human intervention study.
How it was done
TMAO, made from TMA in the body, has been linked to heart and metabolic diseases. The authors wanted to find which part of a pomegranate extract was responsible for previously seen reductions in TMA production.
They used a small-scale model of the human colon with human faecal bacteria and L-carnitine. They tested individual pomegranate compounds (punicalagin, punicalin, ellagic acid, gallic acid, urolithin A, urolithin B, and gum Arabic) at 2 mg per mL, and measured TMA and related substances over 48 hours.
What it can’t tell you
- This was a lab study using human stool samples, not people. It cannot show what happens in the human body.
- The study did not look at whether punicalagin affects actual TMAO levels or heart disease risk in people.
- The authors did not assess changes in gut bacterial composition, so they cannot say which bacteria are involved.
Who paid
- Funding
- Funded by Wellcome Trust (from the PubMed record).
- Conflicts
- There are no conflicts to declare.
- Authors work at
- Quadram Institute Bioscience, UK; Ain Shams University, Egypt
The paper
- Title
- Punicalagin is the key pomegranate polyphenol inhibiting gut microbial trimethylamine (TMA) production from L-carnitine in an in vitro human colon model
- Type
- Study
- Evidence
- Animals and lab studies
- Summarised from
- Full text
- Licence
- CC BY. Words in quotation marks are the authors’; the rest is our summary.
- Cite
- Haarhuis JE, Gamal El-Din MI, Lamprinaki D, Kroon PA (2026). Punicalagin is the key pomegranate polyphenol inhibiting gut microbial trimethylamine (TMA) production from L-carnitine in an in vitro human colon model. Food & function. doi:10.1039/d5fo04781aFree full textPubMed 41627321DOI
Summary written 30 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error