Resveratrol: 500mg Safety, Trans-Resveratrol vs Resveratrol and Red Wine (UK)

What is resveratrol?

Resveratrol is a polyphenol of the stilbene family that some plants make to defend themselves against fungi, injury and UV light. It is found in the skins of red grapes, in red wine, peanuts, blueberries and cranberries, and in high amounts in the root of Japanese knotweed (Fallopia japonica, also called Polygonum cuspidatum), the usual source of supplements.

Resveratrol became famous in the 2000s when lab studies linked it to longer life in yeast, worms and mice. Those results haven’t been shown in people, and there are no authorised health claims for resveratrol in Great Britain.

Trans-resveratrol vs resveratrol: what’s the difference?

Trans-resveratrol is the main natural form of resveratrol and the one used in most research. “Resveratrol” is the general name covering both the trans and cis forms. Trans-resveratrol can turn into cis-resveratrol when exposed to light. A label that says “trans-resveratrol” with a purity figure tells you exactly how much of the studied form you’re getting.

In Great Britain the novel food rules require food supplements containing authorised synthetic or yeast-made resveratrol to name it “trans-resveratrol” on the label.

Is resveratrol 500mg safe?

Resveratrol 500mg a day is more than three times the 150mg a day that the European Food Safety Authority (EFSA) assessed as safe for adults, and the level Great Britain authorises for synthetic trans-resveratrol. Trials using 500mg to 2g a day for up to a year mostly reported nausea, diarrhoea and weight loss, so it isn’t known to be dangerous, but long-term safety isn’t established.

• Higher doses, more stomach upset: in 40 healthy volunteers taking 0.5g to 5g a day for 29 days, the 2.5g and 5g doses caused mild to moderate stomach and bowel symptoms.
• A warning from a cancer trial: a trial of a 5g a day resveratrol product in people with multiple myeloma (a blood cancer) was stopped early after several developed kidney problems.
• Medicines: EFSA noted that resveratrol may affect liver enzymes (CYP2C9) that break down some medicines, which is why GB labels must say people using medicines should only take it under medical supervision.

Is resveratrol 500mg legal in the UK?

It depends on the source. Synthetic trans-resveratrol is authorised in Great Britain only up to 150mg a day, in capsules or tablets, for adults, so a 500mg daily dose from that source goes beyond its authorisation. Resveratrol extracted from Japanese knotweed was sold in food supplements before the novel food rules began, and GB rules for yeast-made trans-resveratrol refer to the “normal use” of knotweed extract rather than a fixed cap. If a 500mg product doesn’t say where its resveratrol comes from, ask the seller.

How much resveratrol should you take a day?

There is no recommended daily amount, because resveratrol isn’t an essential nutrient. The best safety evidence is for up to 150mg a day in adults. If you choose to take it, staying at or below that level, with food, is the cautious choice; check with your GP or pharmacist first if you take any medicine.

What does resveratrol do? What the research shows

In people, resveratrol’s effects are small and uncertain. A 2026 umbrella review of 45 meta-analyses found the strongest evidence for slightly lower blood pressure in people with type 2 diabetes, slightly smaller waists, and a little lower cholesterol in overweight adults. Most famous claims, such as slowing ageing, come from lab and animal studies.

Our honest summary: resveratrol is interesting in the lab, but there’s no good evidence that a supplement helps healthy people live longer or age more slowly. If blood pressure or blood sugar is your concern, speak to your GP; diet, activity and prescribed treatment do far more. For other researched supplements in this area, see berberine (with its medicines caution) and omega-3.

Resveratrol is often sold alongside NMN as an “anti-ageing stack”; our guide to NAD+, NMN and NR supplements explains their UK legal status and the human evidence. For the antioxidant CoQ10, see coenzyme Q10.

People interested in resveratrol often look at related compounds too: see our guides to astaxanthin, turmeric, green tea and dark chocolate, which all contain polyphenols or pigments studied for similar reasons.

Is red wine a good source of resveratrol?

No. Red wine contains on average about 1.9mg of trans-resveratrol per litre, so a 175ml glass gives roughly 0.3mg. Matching a 150mg supplement would take around 80 litres of wine, and 500mg around 260 litres. Any health effect of moderate drinking can’t be explained by resveratrol, and alcohol itself carries real risks.

• The “French paradox”: the idea that red wine explains lower heart disease in France has not held up as a resveratrol story; researchers have pointed out that the amounts are thousands of times lower than doses used in trials.
• Alcohol limits: the NHS advises no more than 14 units a week, spread over 3 or more days, with several drink-free days.
• Food sources: red grapes, peanuts, blueberries and dark chocolate contain small amounts too.

If you’re cutting back, see alcohol and sleep, the best alcohol-free drinks in the UK and our reishi cacao as an alcohol alternative.

Resveratrol side effects, medicines and who should avoid it

Resveratrol is usually well tolerated at up to 150mg a day. Higher doses can cause nausea, stomach cramps and diarrhoea. The bigger issue is medicines: resveratrol may change how some are broken down, and it may affect blood clotting, so GB labels must say people using medicines should only take it under medical supervision.

• Blood thinners: if you take warfarin, a DOAC such as apixaban or rivaroxaban, clopidogrel or daily aspirin, speak to your GP, pharmacist or anticoagulant clinic before taking resveratrol, as it may add to the risk of bleeding.
• Other regular medicines: EFSA flagged possible interactions with medicines broken down by the CYP2C9 enzyme, which include warfarin and some anti-inflammatory painkillers and diabetes medicines. Ask your pharmacist.
• Pregnancy and breastfeeding: avoid it; it hasn’t been shown to be safe.
• Children: GB authorisation for synthetic trans-resveratrol is for adults only.
• Kidney disease, cancer treatment or a hormone-sensitive condition: ask your specialist first.
• Before surgery or dental work: tell your surgeon or dentist about every supplement you take.

Grapefruit and some supplements affect similar liver enzymes; our guide to the grapefruit warning and medicines explains how these interactions work. If you take warfarin, our vitamin K2 guide covers another supplement to check first.

How to choose a resveratrol supplement

Choose a resveratrol supplement that states the trans-resveratrol content in mg and its source, gives a daily amount you’re comfortable with (the best safety evidence is for 150mg or less), carries the GB line about people using medicines, and makes no anti-ageing promises. No health claims are authorised for resveratrol in Great Britain.

Wondering what’s worth taking as you get older? See supplements for women over 40, supplements for men over 50, are multivitamins worth taking? and can you overdose on vitamins?