Guide
What is resveratrol? A plain guide
Resveratrol is a plant compound found in red wine and made commercially from Japanese knotweed root. This guide covers what it is, what a capsule label means, and what is known about absorption.
Resveratrol is a polyphenol, a compound some plants make, found in red wine and sold as a capsule supplement, usually extracted from the root of Japanese knotweed (Polygonum cuspidatum). On a supplement label it often appears as "trans-resveratrol", the form labels name. A "600 mg" capsule may hold 600 mg of extract or of resveratrol, depending on the label.
What resveratrol is
Chemically it is a stilbene, a type of polyphenol. Plants make it, and it is the same family of compounds people mean when they talk about "red wine antioxidants". "Trans" describes the arrangement of the molecule and is the form supplement labels name. You will see "resveratrol", "trans-resveratrol" and "resveratrol complex" used loosely, and they are not interchangeable (see below).
It is pronounced rez-VAIR-uh-trol. A short answer to "what is it for" belongs on a separate page, because that is a question about research, not definition: resveratrol benefits: what the research does and doesn't show.
What is in resveratrol?
That depends on the product. A capsule can contain pure resveratrol, a plant extract that is partly resveratrol, or a blend with other ingredients. The only way to know is the Supplement Facts panel. Our own label, for example, lists one ingredient row: 600 mg of Japanese knotweed root complex per capsule, containing 50% trans-resveratrol. By the label's own figure that is about 300 mg of trans-resveratrol per capsule; that is arithmetic from the 50%, not a measured value, and the panel does not say what the other half is. Other ingredients are hypromellose (a vegetable capsule) and microcrystalline cellulose. Details are on the Resveratrol product page.
What foods contain resveratrol?
Red wine is the food source we can put a number on. One survey of about 135 samples of red wine from a single Spanish grape variety measured total resveratrol, as resveratrol equivalents, at an average of 18.8 mg per litre, with the highest-content wines reaching about 30 mg per litre. At 30 mg/L, a 150 mL glass would hold about 4.5 mg (our arithmetic), and that is the top of the range for one variety, so a typical glass is lower. Grapes, berries and peanuts are often listed as sources too, but we have not verified a per-serving figure for them, so we give none.
Resveratrol supplement vs resveratrol in skin care
A serum applied to skin and a capsule swallowed are different products with different questions around them. This page is about the capsule. We do not cover serums, and nothing here describes what a serum does.
How well is it absorbed?
A 2004 study gave six healthy volunteers a 25 mg oral dose of radiolabelled resveratrol. At least 70% was absorbed. But only trace amounts of unchanged resveratrol (under 5 ng/ml) showed up in plasma, because the body converts it quickly into sulfate and glucuronide forms. The authors called the systemic bioavailability "very low". The study was tiny and used one low dose, so it cannot tell you what happens at other doses or in other forms, but it is why "how much resveratrol is in the capsule" and "how much your body ends up with" are different questions.
Questions people ask
What does resveratrol do?
That is a question about research results, and we answer it only on the research page: what the research does and doesn't show. The short version is that human trial results are mixed and many are at doses that differ from what capsules contain.
What is resveratrol made from?
Supplement resveratrol is commonly extracted from Japanese knotweed root. Ours is labelled as Polygonum cuspidatum root.
What is NAD resveratrol, or resveratrol with ferulic acid?
Those are combinations: resveratrol sold with an NAD precursor, or a skin serum that pairs it with ferulic acid. We do not sell either, and we cover only single-ingredient resveratrol capsules here.
What is the downside of resveratrol?
Low absorption of the unchanged compound (above), unclear dose-to-effect evidence, and cautions for people on prescription medicines. See resveratrol side effects and resveratrol and medications.
Which resveratrol supplement should I choose?
The one whose label tells you how much resveratrol is in it, in plain numbers. How to choose a good resveratrol walks through reading one.
Who discovered or makes resveratrol?
We have not verified a discovery date to a source, so we do not state one. Supplement makers generally extract it from knotweed root.
Sources
- High absorption but very low bioavailability of oral resveratrol in humans Most of a 25 mg dose was absorbed, but almost none stayed in the blood as plain resveratrol; it was converted to other compounds.
- Determination of piceid and resveratrol in Spanish wines deriving from Monastrell (Vitis vinifera L.) grape variety In one Spanish red-wine variety, total resveratrol ran from about 19 mg a litre on average to about 30 mg a litre at the high end.
*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
