Resveratrol shot to fame in the 1990s thanks to the “French Paradox” - the observation that French people seemed to have lower rates of heart disease despite eating plenty of butter, cheese, and other high-fat foods. The popular explanation? All that red wine they drink contains resveratrol.

Since then, resveratrol has attracted considerable research interest, with studies examining potential effects on ageing, diabetes, cancer, and cognitive decline. But how much of this holds up under scrutiny?

What is resveratrol?

Resveratrol is a polyphenolic compound that plants produce as a defence mechanism against stress - whether from infections, ultraviolet radiation, or physical damage. You can think of it as part of the plant’s immune system.

The compound appears in over 300 edible plants. The richest dietary sources include grapes (especially the skins), blueberries, cranberries, peanuts, and cocoa. Red wine contains resveratrol because it’s made with grape skins left in contact with the juice during fermentation.

The first isolation of resveratrol came in 1940 when Japanese researcher Michio Takaoka extracted it from white hellebore roots. Today, most supplements derive their resveratrol from Japanese knotweed (Polygonum cuspidatum), which has particularly high concentrations.

There are two forms of resveratrol: cis and trans isomers. The trans form (trans-resveratrol) is more stable and more common in nature. It’s also the form that shows biological activity in most research, which is why supplement manufacturers focus on it.

What does the research actually show?

I should be upfront here: resveratrol research presents a complicated picture. Many studies show promising results, but the human trials often involve small sample sizes, and effects tend to be modest. Let’s look at what the evidence says for each claimed benefit.

1. Blood pressure regulation

High blood pressure affects roughly 1 billion people worldwide, with projections suggesting this will reach 1.56 billion by 2025 [1]. While medication and lifestyle changes remain the primary treatments, adherence rates are notoriously poor.

A meta-analysis pooling 17 randomised controlled trials with 681 participants found that resveratrol showed favourable but non-significant effects on systolic, mean arterial, and pulse pressure. It showed no effect on diastolic blood pressure [2].

Interestingly, subgroup analysis revealed that blood pressure improvements were most pronounced in two groups: those taking 300 mg or more daily, and those with diabetes.

The bottom line? There might be something here for specific populations, but resveratrol isn’t going to replace your blood pressure medication anytime soon.

2. Memory and cognitive function

With the global population of over-60s expected to double by 2050, age-related cognitive decline represents a growing concern. The rate of mental decline varies considerably between individuals, influenced by exercise, diet, and other lifestyle factors.

Here’s where I need to temper expectations. A systematic review of 4 randomised controlled trials involving 226 participants found no significant effect of resveratrol supplementation on memory or cognitive performance [3]. The studies assessed learning ability, delayed recall, and recognition using standard auditory verbal learning tests.

The evidence simply isn’t there yet. Larger, well-designed trials might tell a different story, but based on current data, resveratrol won’t sharpen your memory.

3. Bone health

Osteoporosis causes approximately 1.5 million fractures annually in the United States alone. The condition becomes more prevalent with age, characterised by bone loss and structural changes that increase fracture risk.

A meta-analysis of 6 RCTs with 264 participants found that resveratrol supplementation significantly improved two bone markers: serum alkaline phosphatase (ALP) and bone-specific alkaline phosphatase (BAP) [4]. However, it didn’t improve serum calcium, osteocalcin, or collagen markers.

The proposed mechanism involves resveratrol promoting osteoblast (bone-building cell) formation whilst inhibiting osteoclast (bone-resorbing cell) activity. That’s promising in theory, but the small sample sizes mean we can’t draw firm conclusions yet.

4. Cardiovascular health

Cardiovascular disease remains the leading cause of death from non-communicable diseases globally. In the United States, someone dies from cardiovascular disease every 39 seconds.

A pooled analysis of 21 randomised controlled trials involving 681 overweight or obese participants found that resveratrol supplementation significantly reduced total cholesterol, systolic blood pressure, and fasting blood glucose [5].

Subgroup analysis showed these benefits were most pronounced with daily doses of 300 mg or higher. For overweight and obese individuals specifically, there appears to be genuine potential here.

5. Hyperlipidaemia

Hyperlipidaemia (elevated blood fats) encompasses high cholesterol, high triglycerides, or both. It’s closely linked to type 2 diabetes, hypertension, and heart disease.

Unfortunately, a comprehensive meta-analysis of 21 RCTs with 949 adults found that resveratrol did not significantly improve any lipid values - neither total cholesterol, LDL cholesterol, HDL cholesterol, nor triglycerides [6].

This is worth noting because it contradicts the cardiovascular findings above. The discrepancy likely comes down to different study populations and methodologies. Based on current evidence, I wouldn’t recommend resveratrol specifically for managing cholesterol levels.

6. Weight loss

Obesity contributes to numerous conditions including various cancers, type 2 diabetes, hypertension, stroke, heart disease, osteoarthritis, and gallbladder disease.

A meta-analysis of 28 randomised controlled trials with 1,514 participants examined resveratrol’s effects on body composition [7]. Taking a median dose of 300 mg for 12 weeks was associated with modest reductions in body weight (0.51 kg), BMI (0.17 kg/m²), and waist circumference (0.79 cm). Fat mass showed no significant change.

Subgroup analysis found the weight loss effect was most apparent with doses under 500 mg daily, interventions lasting 3 months or longer, and in participants who were already obese.

Honest assessment: these are small effects. Half a kilogram over three months isn’t going to transform anyone’s physique. Don’t expect resveratrol to replace diet and exercise.

7. Blood sugar control in diabetes

Type 2 diabetes currently affects about 150 million people worldwide, with rates climbing due to obesity and sedentary lifestyles.

A meta-analysis of 9 RCTs with 283 diabetic participants found that resveratrol supplementation improved fasting blood glucose, insulin resistance index, and insulin levels [8]. Daily doses above 100 mg appeared most effective.

The mechanism may involve activation of SIRT1 (a histone deacetylase) and AMP-activated protein kinase - both involved in metabolic regulation. This is one of the more promising applications for resveratrol, though sample sizes remain limited.

8. Non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) affects roughly one-third of Western and Asian populations. The condition ranges from simple fat accumulation to inflammation, fibrosis, and eventually cirrhosis.

Given resveratrol’s anti-inflammatory and antioxidant properties, researchers hoped it might help. A meta-analysis of 4 clinical trials with 158 participants found no positive effect on liver fibrosis or disease markers like AST and ALT [9].

The evidence simply doesn’t support using resveratrol for fatty liver.

9. Cancer

Cancer remains among the top 10 causes of death worldwide. Chemotherapy and radiation are standard treatments, but cancer cells frequently develop resistance.

A systematic review of laboratory and animal studies found that resveratrol can promote apoptosis (programmed cell death) in cancer cells, inhibit proliferation, and reduce inflammation [10]. It may also enhance the effectiveness of conventional anticancer drugs.

However, I must emphasise: these findings come from test tubes and animal models. No large-scale human trials have confirmed anti-cancer effects, and we don’t know the right dosage or whether it’s safe alongside cancer treatment. This is interesting science but not yet actionable medicine.

Wet macular degeneration involves abnormal blood vessel growth in the eye, leading to macular oedema and potentially blindness. Current treatment uses VEGF inhibitors to slow abnormal vessel formation.

Preliminary research suggests resveratrol can inhibit VEGF and slow choroidal neovascularisation in laboratory settings [11]. One small study found that resveratrol increased choroidal thickness (indicating improved blood flow) compared to placebo [12].

But no studies have directly confirmed benefits for macular degeneration in patients. This remains theoretical.

11. Longevity

Caloric restriction - reducing daily intake by 20-40% while maintaining nutrition - consistently extends lifespan across species in laboratory studies. A 6-month human trial found that caloric restriction reduced insulin levels, body temperature, and DNA damage [13].

Resveratrol appears to activate some of the same pathways as caloric restriction, particularly through the SIRT1 gene [14]. In mice fed high-calorie diets, those receiving resveratrol showed 31% reduced mortality alongside improved insulin sensitivity and mitochondrial function [15].

Will resveratrol extend human lifespan? Nobody knows. The animal data is intriguing, but humans aren’t mice, and we live considerably longer, making such studies impractical.

12. Ulcerative colitis

Ulcerative colitis involves chronic inflammation of the intestinal lining, causing bloody diarrhoea, abdominal cramps, and increased bowel cancer risk.

A double-blind controlled study gave 500 mg daily resveratrol to 56 patients with mild to moderate ulcerative colitis for 6 weeks [16]. The resveratrol group showed reduced malondialdehyde (an oxidative stress marker) and increased antioxidant capacity. More importantly, disease activity and quality of life improved significantly compared to placebo.

This is one of the more convincing findings, though replication in larger trials would strengthen confidence.

What are the side effects?

Resveratrol remains relatively understudied in humans, so we don’t have complete safety data. However, available evidence suggests it’s generally well-tolerated.

One study tested doses between 2.5 g and 5.0 g daily over 29 days [17]. Participants experienced mild gastrointestinal symptoms including nausea, flatulence, abdominal discomfort, and diarrhoea. Symptoms typically appeared 2-4 days after starting and occurred 30-60 minutes after taking the supplement.

Most supplements contain 100-500 mg, well below the doses causing these problems.

Safety precautions

Pregnancy and breastfeeding: No safety data exists for pregnant or nursing women. Avoid to be cautious.
Anticoagulant interactions: Resveratrol may have blood-thinning effects. Don’t combine with anticoagulants, antiplatelet drugs, or NSAIDs including aspirin, clopidogrel, diclofenac, ibuprofen, naproxen, enoxaparin, heparin, or warfarin [18].
Drug metabolism: Resveratrol may interfere with liver enzymes (particularly CYP1A2) that metabolise many medications. This could alter drug effectiveness or cause unexpected reactions. Consult a pharmacist before combining with any medication.
Oestrogen-sensitive conditions: Animal studies suggest resveratrol has mild oestrogenic activity [19]. Those with breast, ovarian, or uterine cancer, endometriosis, or uterine fibroids should avoid it until human studies clarify the risk.
Surgery: Stop resveratrol at least 2 weeks before scheduled surgery due to potential bleeding risk.

References

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Liu Y, et al. Effect of resveratrol on blood pressure: a meta-analysis of randomized controlled trials. Clin Nutr. 2015;34(1):27-34. PubMed
Marx W, et al. Effect of resveratrol supplementation on cognitive performance and mood in adults: a systematic literature review and meta-analysis of randomized controlled trials. Nutr Rev. 2018;76(6):432-443. PubMed
Kok N, et al. Effects of resveratrol on bone health markers in postmenopausal women: a meta-analysis. Crit Rev Food Sci Nutr. 2020;60(17):2989-2998. PubMed
Hausenblas HA, et al. Resveratrol treatment as an adjunct to pharmacological management in type 2 diabetes mellitus - systematic review and meta-analysis. Mol Nutr Food Res. 2015;59(1):147-59. PubMed
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Tabrizi R, et al. The effects of resveratrol intake on weight loss: a systematic review and meta-analysis of randomized controlled trials. Crit Rev Food Sci Nutr. 2020;60(3):375-390. PubMed
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Elgebaly A, et al. Resveratrol supplementation in patients with non-alcoholic fatty liver disease: systematic review and meta-analysis. J Gastrointestin Liver Dis. 2017;26(1):59-67. PubMed
Athar M, et al. Resveratrol: a review of preclinical studies for human cancer prevention. Toxicol Appl Pharmacol. 2007;224(3):274-83. PubMed
Bola C, et al. Resveratrol and ophthalmic diseases. Graefes Arch Clin Exp Ophthalmol. 2014;252(5):699-713. PMC
Richer S, et al. Observation of human retinal remodeling in octogenarians with a resveratrol based nutritional supplement. Nutrients. 2016;8(3):141. PubMed
Heilbronn LK, et al. Effect of 6-month calorie restriction on biomarkers of longevity, metabolic adaptation, and oxidative stress in overweight individuals: a randomized controlled trial. JAMA. 2006;295(13):1539-48. PMC
Baur JA, et al. Therapeutic potential of resveratrol: the in vivo evidence. Nat Rev Drug Discov. 2006;5(6):493-506. PMC
Baur JA, et al. Resveratrol improves health and survival of mice on a high-calorie diet. Nature. 2006;444(7117):337-42. PubMed
Samsamikor M, et al. Resveratrol supplementation and oxidative/anti-oxidative status in patients with ulcerative colitis: a randomized, double-blind, placebo-controlled pilot study. Arch Med Res. 2016;47(4):304-9. PubMed
Brown VA, et al. Repeat dose study of the cancer chemopreventive agent resveratrol in healthy volunteers: safety, pharmacokinetics, and effect on the insulin-like growth factor axis. Cancer Res. 2010;70(22):9003-11. PMC
Pace-Asciak CR, et al. The red wine phenolics trans-resveratrol and quercetin block human platelet aggregation and eicosanoid synthesis: implications for protection against coronary heart disease. Clin Chim Acta. 1995;235(2):207-19. PubMed
Rietjens IM, et al. The potential health effects of dietary phytoestrogens. Br J Pharmacol. 2017;174(11):1263-1280. PubMed