Resveratrol: Supplement Forms and How to Choose One
Resveratrol became famous through the "French paradox" and through early research on ageing in yeast and mice. Today it is sold in many forms with very different labels and prices. Our editors explain the main formats, why bioavailability is the central challenge, what the evidence says for active people and how to read a label.
What resveratrol is
Resveratrol is a polyphenol of the stilbene family. Plants produce it in response to stress, infection or ultraviolet light. Small amounts are found in red grape skins, red wine, peanuts and berries, while the root of Japanese knotweed (Polygonum cuspidatum) is a much richer source.
It exists in two forms: trans-resveratrol and cis-resveratrol. The trans form is the one most studied and considered biologically active. Exposure to light and heat can convert trans to cis, which is one reason storage matters.
Interest exploded after studies suggested that resveratrol activates sirtuins, enzymes involved in cellular ageing, and mimics some effects of calorie restriction. Later work questioned how directly it acts on sirtuins, but research into metabolism, cardiovascular health and inflammation continued.
In humans, results have been mixed. A study by Timmers and colleagues in obese men reported some calorie restriction–like metabolic changes over 30 days, while many other trials found small or no effects. The picture is far from the bold claims seen in marketing.
The bioavailability problem
The main obstacle with resveratrol is that very little reaches the bloodstream unchanged. Walle and colleagues showed in 2004 that while about 70% of an oral dose is absorbed, it is rapidly converted in the gut wall and liver into sulphate and glucuronide metabolites. Free resveratrol in plasma was barely detectable.
Boocock and colleagues confirmed in a dose-escalation study that even high single doses produced low peak concentrations of free resveratrol, with metabolites far more abundant. Whether these metabolites have their own activity remains an open question.
Resveratrol is also poorly soluble in water, which limits how much can dissolve in the gut. Many newer formulations are designed specifically to address solubility or to protect the molecule from rapid metabolism.
When comparing products, it is therefore more useful to ask how a form handles solubility and metabolism than to focus only on the number of milligrams on the label.
Main forms on the market
Most supplements contain trans-resveratrol extracted from Japanese knotweed. Labels often state the purity, such as 50% or 98% trans-resveratrol. Lower-purity extracts contain other plant compounds, including emodin, which can have a laxative effect.
Synthetic and fermentation-derived trans-resveratrol is also available. These sources can achieve high purity and consistent quality. In Great Britain and the EU, synthetic trans-resveratrol has novel food authorisation with a maximum intake for adults of 150 mg per day in food supplements.
Micronised resveratrol uses smaller particles to improve dissolution. A micronised formulation known as SRT501 was tested in clinical research, but a trial in multiple myeloma was stopped because of kidney problems in patients, a reminder that higher exposure can bring new risks.
Other formats include liposomal and other "enhanced" delivery systems, combinations with piperine to slow metabolism, and the related compound pterostilbene, which has two methoxy groups that make it more lipophilic. The table summarises the main options.
| Form | Main feature | Points to consider |
|---|---|---|
| Knotweed extract (standardised) | Most common, natural source | Check trans-resveratrol percentage; low purity may contain emodin |
| High-purity synthetic or fermented | Consistent content | Within authorised limits in GB/EU |
| Micronised | Better dissolution | Limited data in healthy people |
| Liposomal or emulsified | Designed to improve absorption | Claims often based on small or company-funded studies |
| With piperine | May slow metabolism | Potential drug interactions |
| Pterostilbene | Related compound, more lipophilic | Different molecule; separate evidence base |
Resveratrol and exercise: a word of caution
Resveratrol is sometimes promoted for endurance and recovery. Animal studies suggested it could improve mitochondrial function and exercise capacity in mice, which attracted a lot of attention.
Human research has been less encouraging. A study by Gliemann and colleagues in aged men found that resveratrol blunted some of the positive cardiovascular effects of exercise training, including improvements in blood pressure and cholesterol, compared with placebo.
One possible explanation is that exercise relies partly on oxidative stress signals to trigger adaptation. High doses of antioxidants may dampen those signals, a phenomenon also observed with high-dose vitamins C and E in some studies.
That does not mean resveratrol is harmful for everyone who trains, but it does suggest that people aiming for training adaptations should not assume more antioxidants are always better.
How to choose and use a product
If you decide to try resveratrol, choose a product that clearly states the amount of trans-resveratrol per serving rather than just the weight of extract. Look for information about the source and purity.
Keep intake within the authorised limits. In GB and the EU, food supplement doses of synthetic trans-resveratrol should not exceed 150 mg per day for adults. Higher doses used in some trials were taken under medical supervision.
Before use, consider these points:
- resveratrol may affect blood clotting, so caution is needed with anticoagulants or antiplatelet drugs;
- it may interact with medicines metabolised by liver enzymes;
- it has weak oestrogen-like activity, which matters for people with hormone-sensitive conditions;
- pregnant and breastfeeding women should avoid it due to lack of data;
- digestive upset is the most common side effect at higher doses.
Store resveratrol in a cool, dark place to slow conversion of the trans form. Opaque packaging and tightly closed containers help protect it.
Conclusions of the editorial team
Resveratrol is a well-studied polyphenol, but its low bioavailability and inconsistent human results mean expectations should be modest.
The key choice is between standardised knotweed extract and high-purity synthetic or fermented trans-resveratrol, with newer delivery systems offering potential but limited evidence.
Active people should be aware that high-dose antioxidants may interfere with some training adaptations. Clear labelling, sensible doses and medical advice where needed are the best safeguards.
Related topics on our site include quercetin for athletes, antioxidants and training adaptation, and how to evaluate "enhanced absorption" claims.
References
- Walle T, Hsieh F, DeLegge MH, et al. High absorption but very low bioavailability of oral resveratrol in humans. Drug Metab Dispos. 2004;32(12):1377–1382.
- Boocock DJ, Faust GE, Patel KR, et al. Phase I dose escalation pharmacokinetic study in healthy volunteers of resveratrol, a potential cancer chemopreventive agent. Cancer Epidemiol Biomarkers Prev. 2007;16(6):1246–1252.
- Timmers S, Konings E, Bilet L, et al. Calorie restriction-like effects of 30 days of resveratrol supplementation on energy metabolism and metabolic profile in obese humans. Cell Metab. 2011;14(5):612–622.
- Gliemann L, Schmidt JF, Olesen J, et al. Resveratrol blunts the positive effects of exercise training on cardiovascular health in aged men. J Physiol. 2013;591(20):5047–5059.
- Popat R, Plesner T, Davies F, et al. A phase 2 study of SRT501 (resveratrol) with bortezomib for patients with relapsed and or refractory multiple myeloma. Br J Haematol. 2013;160(5):714–717.
- EFSA Panel on Dietetic Products, Nutrition and Allergies. Safety of synthetic trans-resveratrol as a novel food pursuant to Regulation (EC) No 258/97. EFSA J. 2016;14(1):4368.
