Guide
Who should not take resveratrol?
People on prescription medicines, with a health condition, who are pregnant or nursing, or under 18 should not start resveratrol without asking a doctor. We found no verified trial in those groups.
Anyone who takes prescription medication, has a health condition, is pregnant or nursing, or is under 18 should ask a doctor before taking resveratrol. We found no verified trial in those groups. In 42 healthy adults, 1,000 mg a day for 4 weeks changed how several medicine-processing enzymes worked.
Who should ask a doctor first
- People who take prescription medication, including blood thinners. The enzyme study below is the reason for the caution; it is a general one, not a reported finding for any named drug. See resveratrol and medications.
- People with a known medical condition. The trials we cite recruited healthy volunteers or specific groups, and we cannot extend any result to you.
- Anyone pregnant or nursing, or under 18. This is caution only. Our label says to consult a physician, and we give no use guidance for these groups.
- Anyone planning a higher dose than the label. In a 29-day study of 40 healthy volunteers, the 2.5 g and 5 g daily doses caused mild to moderate gastrointestinal symptoms.
The evidence behind the caution
In a 2010 study, 42 healthy volunteers took 1,000 mg of resveratrol once a day for 4 weeks. Measures of the enzymes CYP3A4, CYP2D6 and CYP2C9 fell, and CYP1A2 rose. The authors concluded that doses like this could lead to more adverse drug reactions or change how well a drug works. By the label's 50% figure our capsule's directions come to about 600 mg of trans-resveratrol a day, below 1,000 mg, but nobody has tested what a lower dose does to these enzymes, so we do not treat the lower number as a safe harbour.
Resveratrol, kidneys and liver: what we could not verify
People search for whether resveratrol is safe for the kidneys or liver. We found no trial we could verify that tested resveratrol in people with kidney or liver disease, and the safety studies above enrolled healthy volunteers. That is a gap, not a clean bill of health. If you have kidney or liver problems, ask your doctor before taking resveratrol.
Who should take resveratrol?
Nobody needs to. There is no deficiency to correct and no established Daily Value (our label prints "Daily Value not established"). What it may or may not do is on the research page: resveratrol benefits: what the research does and doesn't show.
Questions people ask
Who should avoid resveratrol?
See the list above: anyone on medication, with a health condition, pregnant, nursing or under 18 should ask first.
Is resveratrol safe for kidneys?
Not verified either way for people with kidney disease. See the section above and ask your doctor.
Can resveratrol cause liver damage?
We found no verified report in the studies we read. We did not find a trial in people with liver disease, so ask your doctor if that applies to you.
Who can take resveratrol?
Healthy adults were the participants in the safety studies cited here. For anyone else, ask a doctor. Our directions are one capsule twice a day, 20 to 30 minutes before a meal; do not exceed it. Label facts are on the product page.
Who makes or sells resveratrol, and who invented it?
Many supplement companies sell it, generally extracted from Japanese knotweed root. We have not verified a discovery date to a source, so we do not give one.
What is the risk of side effects?
Sources
- Resveratrol modulates drug- and carcinogen-metabolizing enzymes in a healthy volunteer study In 42 healthy adults, 1,000 mg a day for 4 weeks changed how several liver enzymes that process medicines were working.
- Repeat dose study of the cancer chemopreventive agent resveratrol in healthy volunteers: safety, pharmacokinetics, and effect on the insulin-like growth factor axis In 40 healthy adults, 0.5 to 5 g a day for 29 days was called safe, but the two highest doses caused mild to moderate stomach and gut symptoms.
*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.
