Quick answer

The trials behind resveratrol's one graded effect used 30 to 500 mg a day. The European Union caps synthetic trans-resveratrol in supplements at 150 mg a day for adults, and a 2026 review saw weaker or less favorable results at 500 mg a day or more.^1,2

Key facts

Single doses of 30, 90 and 270 mg were compared in one trial, and the artery response grew with the dose.³
Healthy volunteers have taken 0.5 to 5 g a day for up to 29 days; gut problems appeared from 2.5 g.⁴
At 1 g a day, resveratrol changed the activity of liver enzymes that clear many medicines.⁵
Food supplies far less: a median of 0.1 mg a day in a large Spanish study.⁶

The amounts used in studies

The trials behind the blood vessel finding gave 30 to 500 mg a day for 1 to 24 weeks.¹

Daily amounts in resveratrol studies^{1,4,7,8,9,10,11}
Study	Daily amount	What happened
Blood vessel trials, pooled	30 to 500 mg for 1 to 24 weeks	Small rise in artery widening
28 adults with a high body mass index	75 mg for 6 weeks	Larger artery widening response than with placebo
27 inactive men around 65, in training	250 mg for 8 weeks	Smaller fitness gain than with placebo
74 middle-aged men	150 or 1,000 mg for 16 weeks	Main measures unchanged; LDL rose at 1,000 mg
29 overweight adults aged 65 or older	300 or 1,000 mg for 90 days	Two vessel and clotting markers rose at 1,000 mg
40 healthy volunteers	0.5 to 5 g for 29 days	Gut problems at 2.5 and 5 g

May support normal blood vessel function*^1,7

Early evidence

A 2022 meta-analysis of randomized trials found a small improvement in flow-mediated dilation, a test of how well an artery widens (about 1.4 percentage points); a 2026 umbrella review rated this as moderate-certainty evidence from 8 trials (603 people) that used 30 to 500 mg a day for 1 to 24 weeks. The trials enrolled mixed groups that included people under medical care, none used this product's 600 mg label dose, and the umbrella review saw weaker or less favorable results overall at 500 mg a day or more.

Amount studied: 30 to 500 mg a day for 1 to 24 weeks

Is more better?

A 2026 review of 45 meta-analyses saw weaker or less favorable results at 500 mg a day or more, and in trials longer than 12 weeks.¹

In the two longer trials that compared amounts directly, the higher one did not come out ahead. In middle-aged men, 1,000 mg did no more than 150 mg over 16 weeks, and in older adults 1,000 mg raised two markers that 300 mg left alone.^10,11

Only the single-dose study found a clear dose pattern, with a larger artery response after 270 mg than after 30 mg, measured one hour later.³

Reading a resveratrol label

Labels may give the weight of a whole extract or of trans-resveratrol alone. A knotweed extract sold as 50% trans-resveratrol, for example, holds 300 mg of trans-resveratrol in 600 mg of extract. Our own label does not say what makes up the other half.¹²

The European Union's authorization covers synthetic trans-resveratrol that is at least 99% pure.²

Compare products by the trans-resveratrol per day, counting how many capsules the label directs.

Europe's 150 mg limit

The European Union allows synthetic trans-resveratrol in supplements for adults at up to 150 mg a day.²

The European Union requires labels of supplements with trans-resveratrol to say that people taking medicines should use them only under medical supervision, because it may interact with specific medicines.²

The decision covers synthetic trans-resveratrol in capsules or tablets, for adults only. It does not mention plant extracts.²

What's in ours

Each capsule of ours gives 300 mg of trans-resveratrol from 600 mg of knotweed extract, and the label directs two a day, 600 mg in total. One capsule is closer to the 30 to 500 mg studied, and two are four times Europe's cap.^1,2

Higher amounts and safety

Higher total and LDL cholesterol at 1,000 mg a day in a 16-week trial of middle-aged men.¹⁰

At 1,000 mg a day for 90 days in older overweight adults, two blood markers linked to blood vessel and clotting risk rose more than with 300 mg or placebo.¹¹

The European Union allows synthetic trans-resveratrol in supplements at no more than 150 mg a day for adults. In a 29-day study of 40 healthy volunteers, 0.5 and 1 g a day were tolerated, while 2.5 and 5 g a day caused mild to moderate gut symptoms.^2,4

Ask your doctor or pharmacist before taking resveratrol with any prescription medicine, especially a blood thinner¹³
Ask first if you are pregnant or breastfeeding, or under 18
Ask first if you have liver disease or take estrogen¹³

Questions people ask

Is 1,000 mg of resveratrol a day too much?

It is well above Europe's 150 mg cap and the 30 to 500 mg used in the vessel trials. At 1,000 mg a day, trials found higher LDL cholesterol in middle-aged men, two raised vessel and clotting markers in older adults, and diarrhea in 30% of women in one study.^1,2,10,11,14

How much resveratrol per day is safe?

Europe allows up to 150 mg a day of synthetic trans-resveratrol for adults. In a 29-day study, healthy volunteers tolerated 0.5 and 1 g a day, while 2.5 g and above caused gut problems.^2,4

Is the dose different for women?

We found no trial that set different amounts for women. In one study of 40 women past menopause, 1 g a day for 12 weeks led six to stop early because of side effects.¹⁴

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Sources

*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.

This page is information, not medical advice. Talk to your doctor or pharmacist about your own situation.