Piceid is resveratrol with a glucose molecule attached. Chemically it is trans-resveratrol-3-O-β-glucoside, also sold under the name polydatin, and it is the most abundant natural form of resveratrol in foods such as grape skin and red wine. The body does not use it exactly like free trans-resveratrol: laboratory studies show that gut enzymes can cut the glucose off and release resveratrol, but piceid itself behaves differently in cells. Here is what the published research says and where it stops.
Table of Contents
- What Piceid Is
- How the Body Handles Piceid
- What Lab Studies Show About Piceid vs. Resveratrol
- The Role of Gut Bacteria
- What the Research Does Not Show
- Piceid in a Red Grape Skin Supplement
- Which Form Fits Your Goals
What Piceid Is
Resveratrol exists in plants in two main structural forms. One is the free molecule, trans-resveratrol, the form used in most human research. The other is piceid, where a sugar (glucose) is chemically bound to the resveratrol molecule. Scientists call this a glycoside. The glucose makes the molecule more water-soluble, and plants often store resveratrol in this bound form.
Because of this, red grape skin extract and red wine contain both forms. In a 2006 study in the European Journal of Nutrition, the authors noted that trans-piceid is more abundant than free resveratrol in red wine.
Quick vocabulary: Piceid, polydatin, trans-piceid and resveratrol-3-O-glucoside all refer to the same molecule. Aglycone means the molecule without its sugar, which here means free resveratrol.
How the Body Handles Piceid
A cell-culture study by Henry-Vitrac and colleagues (European Journal of Nutrition, 2006) used Caco-2 intestinal cell models and rat small-intestine extracts to follow what happens to trans-piceid. The authors reported:
- Piceid crossed the cell layer rapidly, and free trans-resveratrol appeared on both sides of the layer as the experiment progressed.
- Two intestinal enzymes, lactase phlorizin hydrolase and cytosolic β-glucosidase, can both cleave the glucose from piceid.
- The freed resveratrol was then mostly converted to its glucuronide form, mainly through the enzyme UGT1A1.
- The authors proposed two routes: piceid entering the cell through a glucose transporter (SGLT1) and being cleaved inside, or being cleaved at the cell surface with the released resveratrol diffusing in.
In plain terms, this lab model shows that piceid can be converted to resveratrol in the small intestine. The abstract gives no quantitative conversion rate, so it does not tell us how much of a given dose is converted in a person.
What Lab Studies Show About Piceid vs. Resveratrol
A 2013 study in PLoS ONE (Su et al.) compared piceid and resveratrol directly in cell experiments. Both were tested for antioxidant activity and for effects on cell proliferation in liver and breast cancer cell lines. The authors reported:
- Piceid showed higher hydroxyl radical scavenging than resveratrol in the chemical antioxidant assay.
- Resveratrol protected cells against hydrogen peroxide damage.
- At equal concentrations, piceid was less active than resveratrol in the cell proliferation tests, and the authors attributed this probably to cells taking up piceid less readily.
Cell studies are not human outcomes. These experiments used isolated cells and chemical assays, often at concentrations that may not match what a supplement produces in the body. They show how the two molecules differ in a dish, not what either does in a person.
The Role of Gut Bacteria
Intestinal bacteria may also convert piceid. A 2016 study in Bioprocess and Biosystems Engineering (Basholli-Salihu et al.) tested cell extracts from five probiotic strains and found that all five converted piceid to resveratrol, with the speed varying by strain. After 24 hours, L. acidophilus had fully converted piceid, L. plantarum about 72%, L. casei 53% and B. bifidum 32%. In their cell-culture assay, the resveratrol produced showed stronger anti-inflammatory activity than piceid.
This was done with cell-free extracts in the laboratory, so it does not show that probiotics convert piceid in the human gut. It does suggest one reason people respond differently to glycoside forms.
Want a grape-skin source with both forms? Mega Resveratrol Red Grape Skin Resveratrol is a French red grape skin extract containing both piceid and trans-resveratrol. See the full piceid resveratrol product details, or browse all products.
What the Research Does Not Show
- No verified head-to-head human trial. In the sources reviewed for this article, we did not find a human study that directly compares blood levels or outcomes after piceid versus free trans-resveratrol. Claims that one form “absorbs better” in people should be treated as unproven.
- Mixed signals in the lab. Piceid was stronger in one chemical antioxidant assay but weaker in cell proliferation tests, so neither form is simply “better.”
- Most clinical research uses trans-resveratrol. The human trials discussed across this site, including those on dosage and safety, mostly used purified trans-resveratrol, not piceid.
Piceid in a Red Grape Skin Supplement
Mega Resveratrol’s Red Grape Skin Resveratrol lists, per 500 mg capsule, 25% polyphenols (100 mg), 1.5% piceid (7.5 mg) and 10% trans-resveratrol (50 mg). Two points stand out:
- Piceid is a small share of the capsule. The main marker compound is trans-resveratrol, alongside other grape skin polyphenols.
- A whole-extract capsule is a different product from a purified one. If you want a concentrated dose of a single compound, the 99% pure trans-resveratrol capsules fit that purpose, with purity documented on the Independent Lab Certification page.
Which Form Fits Your Goals
- Choose a grape skin extract if you prefer a food-derived extract with a spectrum of grape polyphenols, including piceid, in one capsule.
- Choose purified trans-resveratrol if you want the form used in most human research at a defined dose. Our guide to trans-resveratrol vs. resveratrol explains the isomer difference.
Either way, quality matters more than the label. If you are comparing options, start with pure resveratrol that comes with lab documentation, and see every option on our products page.
Frequently Asked Questions
What is piceid?
Piceid, also called polydatin, is resveratrol bound to a glucose molecule (trans-resveratrol-3-O-β-glucoside). It is the most abundant natural form of resveratrol in red grape skin and red wine.
Is piceid the same as resveratrol?
No. Piceid is the glucoside form; free resveratrol is the aglycone, meaning it lacks the sugar. Gut enzymes and some bacteria can convert piceid to resveratrol in laboratory models.
Is piceid better absorbed than resveratrol?
That has not been shown in the studies reviewed here. Laboratory work shows piceid can cross intestinal cell layers and be converted to resveratrol, but a 2013 cell study found piceid less active than resveratrol at equal concentrations, probably because cells took it up less readily. We did not find a human trial comparing the two.
Is polydatin the same as piceid?
Yes. Polydatin and piceid are two names for trans-resveratrol-3-O-β-glucoside.
Does a red grape skin supplement contain piceid?
Mega Resveratrol’s Red Grape Skin Resveratrol lists 1.5% piceid (7.5 mg) and 10% trans-resveratrol (50 mg) per 500 mg capsule, alongside other grape skin polyphenols.
Should I choose piceid or trans-resveratrol?
It depends on whether you prefer a whole grape skin extract or a purified compound. Most human research used trans-resveratrol, so purified trans-resveratrol matches that evidence most closely.
Conclusion
Piceid is resveratrol’s glucose-bound form: abundant in grape skin, convertible to resveratrol by gut enzymes and some bacteria in laboratory models, but not identical to it in cell studies. The honest summary is that the two forms differ in the lab and that no human comparison has been verified here. Choose by the form and documentation you trust.
Disclaimer: This article is for informational purposes only and does not constitute medical advice. These statements have not been evaluated by the Food and Drug Administration. These products are not intended to diagnose, treat, cure, or prevent any disease. Consult a qualified healthcare professional before starting any new supplement, especially if you are pregnant, nursing, taking medication, or have a medical condition.
Resources cited:
- Su D, et al. “Comparison of Piceid and Resveratrol in Antioxidation and Antiproliferation Activities In Vitro.” PLoS ONE. 2013;8(1):e54505. https://doi.org/10.1371/journal.pone.0054505
- Henry-Vitrac C, et al. “Transport, deglycosylation, and metabolism of trans-piceid by small intestinal epithelial cells.” Eur J Nutr. 2006. https://doi.org/10.1007/s00394-006-0609-8
- Basholli-Salihu M, et al. “Bioconversion of piceid to resveratrol by selected probiotic cell extracts.” Bioprocess Biosyst Eng. 2016;39(12):1879-1885. https://link.springer.com/article/10.1007/s00449-016-1662-1
