Bioactivated Resveratrol Red Grape Antioxidants

Resveratrol comes with more longevity hype than almost anything else on the shelf. The questions our naturopaths ask in store are mostly about separating what the human trials found from what the internet says.

A good fit if

• You're interested in the antioxidant and blood vessel evidence, which is where the human trials are most consistent
• You're comfortable with 150 mg a day, the most an Australian listed medicine can contain
• You're postmenopausal. The two longest trials were Australian, ran for 24 months, and recruited postmenopausal women
• You'd rather hear what the trials didn't find than be sold a longevity story

Check with us first if

• You take any prescription medicine. The required Australian label warning names warfarin specifically, and it applies to every listed resveratrol product.
• You take any kind of antiplatelet or anticoagulant (blood thinner). Lab and animal studies suggest resveratrol has blood-thinning activity, and a trial of a combination product containing Japanese knotweed reduced how readily platelets clumped.
• You're an older adult. Pooled trial data showed a slight rise in ALT (a liver enzyme) in older adults, and the authors advise caution in this group.
• Your liver tests have come back abnormal. The pooled evidence found no benefit in the general population, and above 1,000 mg a day, ALP (another liver marker) rose.
• You have COPD, or you're losing muscle. In a small four-week trial at 150 mg a day, body weight dropped through a loss of lean muscle.
• You have type 2 diabetes. Nearly every blood sugar trial recruited people who already had it, mostly at doses above the Australian cap, and resveratrol isn't a substitute for your treatment.
• You take a herbal combination containing Japanese knotweed. Health professionals are warned these combinations carry interaction risks and added effects on bleeding, blood pressure and blood sugar.
• If you take prescription medicine, check with your doctor, pharmacist or our naturopaths before you start.

• Trans-resveratrol (isolated). Best known for: The purified compound, and the form behind nearly every trial. It's Schedule 1 item 4304, for medicines taken by mouth only, with three required label warnings. Absorption: Heavily broken down. After repeated doses, the sulfate and glucuronide forms reach up to 20.3 times the levels of resveratrol itself, so very little circulates unchanged. Typical use: Up to 150 mg a day in an Australian listed medicine. A label saying trans-resveratrol is telling you which form it's standardised to, not offering a different substance; the TGA treats them as one ingredient.
• Japanese knotweed extract (Reynoutria japonica, also published as Polygonum cuspidatum). Best known for: The plant nearly all commercial resveratrol is extracted from, because its root holds far more than grapes do. It's listed separately at item 4308. Absorption: No human study has compared knotweed extract with isolated resveratrol at matched doses, so there's nothing to tell you either way. Typical use: Sold standardised to a stated number of milligrams of resveratrol, which is the number to read. The only trial we found that named the plant source was a 21-person screening study.
• Grape extract (Vitis vinifera, grape skin). Best known for: A grape polyphenol product rather than a measured resveratrol dose. It's item 5188, allowed with no requirements, which is much freer than resveratrol itself. Absorption: It has far less resveratrol than a capsule, and no source we hold measures how much is in a grape product. Typical use: A pooled analysis that grouped resveratrol, grape and wine trials together found no effect on thinking, mood or blood pressure in people.
• Pterostilbene. Best known for: A related compound from blueberries, differing from resveratrol by two methoxy groups. We found no Schedule 1 entry under that name. Absorption: More fat-soluble, so in lab work it passed through the gut wall more easily, was taken up by cells better and was more stable than resveratrol. Typical use: The only human trial we found is a 12-week pilot in 30 healthy men at 10 or 100 mg, measuring microRNA. Better absorbed isn't the same as better results, and resveratrol's permission doesn't cover it.
• Resveratrol with vitamin C. Best known for: A combination tested in one pilot trial in postmenopausal women with insulin resistance. Absorption: Not measured separately. Typical use: Markers of oxidative damage fell in every group, including vitamin C on its own, which fell the most. So it hasn't been shown that the combination does better than plain vitamin C.

Reference values. There aren't any. Resveratrol isn't a nutrient, so the NHMRC Nutrient Reference Values don't cover it. There's no RDI, adequate intake or upper level, and no such thing as a deficiency.

Typical supplemental range. An Australian listed medicine can contain at most 150 mg of resveratrol in its maximum recommended daily dose, so that's the most you'll see on a local label. Trial doses vary far more widely: 20 mg, 40 mg, 75 mg twice a day, 150 mg, 200 mg, 400 mg, 500 mg, 600 mg, 800 mg, 1,000 mg, and up to 5 g a day in one safety study. The two 24-month Australian trials, both in postmenopausal women, used exactly 150 mg a day. Most of the blood sugar research didn't. Those trials mostly recruited people who already had type 2 diabetes, and pooled fasting blood sugar improved only in that group.

Upper level. The legal limit is the 150 mg cap in item 4304 of Australia's permitted ingredients list (Schedule 1). The research suggests people tolerate more: a review of around 200 trials over 20 years describes resveratrol as generally well tolerated up to 1 g a day, and mild to moderate gut symptoms appeared in healthy volunteers at 2.5 g and above. Neither figure is a dose recommendation. There's no dose for children at all, because the required label warning says it isn't suitable for children.

Worth knowing. Trials ran from a few weeks to two years, and the long Australian ones split the dose into 75 mg twice a day rather than all at once. The evidence doesn't show a best time of day. What it does show is that if you're buying a 150 mg Australian capsule, you're usually not the person those overseas high-dose trials studied. What you need depends on your age, diet and health, so talk to one of our naturopaths.

Food first, where the diet allows it.

• Grapes, and especially grape skins: named as a source in the literature, but no source we hold puts a milligram figure on a serve
• Red wine: named as a source, again unquantified. We can't recommend drinking for it, and nobody should read a wine comparison into a capsule dose
• Peanuts: named as a source; no per-serve figure available
• Berries: named as a source; no per-serve figure available. Blueberries carry pterostilbene, a different compound
• Japanese knotweed root: not a food in Australia: it's the commercial extraction source, and the root holds far more resveratrol than any food does

If any of these sound like you, talk to one of our naturopaths or your doctor before you start.

• Pregnancy and breastfeeding. The label must warn: 'Not recommended for use by pregnant and lactating women'.
• Children. The label must warn: 'Not suitable for children'. There's no dose or safety data for children.
• Warfarin and other medicines. The label must warn: 'Resveratrol may affect the way some medicines work, including Warfarin. Consult your health professional before taking with other medicines'.
• Blood thinners and antiplatelet medicines in general. Lab studies show resveratrol has antiplatelet and blood-thinning activity, and a combination product containing Japanese knotweed lowered platelet sensitivity in a human trial.
• Older adults. The liver enzyme ALT rose by 2.33 U/L in pooled data, and above 1,000 mg a day ALP rose by 5.07 U/L.
• COPD or low muscle mass. A four-week trial at 150 mg a day in 21 people recorded weight loss caused by a 1.79 kg fall in lean mass.
• High doses. 2.5 g and 5 g a day caused mild to moderate gut symptoms in healthy volunteers over 29 days.
• Herbal combinations containing Japanese knotweed. Interactions and added risks around bleeding, blood pressure and blood sugar are documented.
• Long-term human safety data is thin; a dedicated review calls for studies of long-term side effects in the body, and says data on interactions is still lacking.
• We found no TGA safety advisory for this ingredient, so we don't claim anything beyond the three required warnings.
• If you take prescription medicines, check with your doctor, pharmacist or our naturopaths before you start.