Study type: 

Randomised, double-blind, placebo-controlled cross-over study

Purpose:

To investigate the anti-inflammatory and antioxidant effects of resveratrol on healthy smokers.

Dose:

500 mg/day of resveratrol (tablet) or placebo 

Participants:

49 male and female healthy smokers with an average  age of 35

Duration:

30 days of resveratrol and 30 days of placebo

Results:

The researchers observed a reduction of approximately 50% in C-reactive protein concentrations after one month of resveratrol supplementation. A reduction in C-reactive protein concentration is generally considered good because it indicates a decrease in inflammation in the body. C-reactive protein is a protein produced by the liver in response to inflammation, infection, or tissue injury. It is often used as a marker of systemic inflammation in medical tests. The study also found an association between resveratrol supplementation and a decrease in triglyceride concentrations, as well as an increase in total antioxidant status. Maintaining lower levels of triglycerides is important for promoting cardiovascular health, metabolic health, pancreatic function, and liver health. 

No adverse events were reported in either group after supplementation.

Year:

2013

Link:

https://doi.org/10.2174/0929867311320100009

Study type: 

Meta-analysis of randomised controlled trials

Purpose:

To explore the effects of resveratrol supplementation on participants’ blood lipid profile (including substances like triglycerides (fats), cholesterol, and phospholipids). Blood lipid analyses play a crucial role in assessing cardiovascular health and guiding interventions to manage dyslipidemia, a medical condition characterised by abnormally high blood lipid concentrations, which is a major risk factor for cardiovascular disease.

Dosages:

Resveratrol  intervention doses ranged from 5 to 3000 mg/day and intake varied from 4 to 48 weeks

Number of Studies Reviewed:

17 studies were included in this meta-analysis

Results:

The findings from the review showed that the intake of resveratrol could significantly decrease the total cholesterol, triglyceride (a type of fat in the blood). A reduction in these levels can help improve overall cardiovascular health and lower the risk of heart-related problems. 

In addition, low-density lipoprotein cholesterol (“bad” cholesterol) was also found to be reduced by resveratrol supplementation. LDL-cholesterol is often referred to as "bad" cholesterol because high levels of it are associated with an increased risk of cardiovascular diseases, such as heart disease and stroke. Therefore, a lower LDL-cholesterol level is generally considered beneficial for heart health. The reduction of LDL-cholesterol induced by resveratrol was reported to be associated with the antioxidant effect of resveratrol. On the other hand, resveratrol did not alter the level of high-density lipoprotein cholesterol (often referred to as 'good' cholesterol).

Further analysis showed that the reduction of LDL-cholesterol was more significant in trials with a duration of ≥12 weeks and in subjects with type 2 diabetes mellitus. In addition, the analysis revealed that a high dosage of resveratrol, specifically 500 mg/d or more, showed an opposite effect size. This means that, in contrast to the reduced LDL-cholesterol levels observed with a low dosage, a high dosage of resveratrol increased LDL-cholesterol levels. The authors suggest that the dosage of resveratrol intervention is an essential factor that affects the level of LDL-cholesterol and should be considered when designing interventions to reduce LDL-cholesterol levels in individuals with high cholesterol or at risk of heart disease. 

Year:

2022

Link:

https://doi.org/10.3390/nu14183755

Study type: 

Pilot study (uncontrolled)

Purpose:

To investigate the effects of resveratrol in older adults with impaired glucose  tolerance, a medical condition in which an individual's blood sugar levels are higher than normal but not high enough to be classified as diabetes. People with impaired glucose tolerance are at an increased risk of developing type 2 diabetes, as their bodies struggle to regulate blood sugar effectively.

Dose:

1, 1.5, or 2 g/day of resveratrol

Participants:

10 men and women with an average age of 72 years, diagnosed with impaired glucose tolerance

Duration:

4 weeks 

Results:

The researchers observed that the fasting blood sugar of participants taking resveratrol for 4 weeks did not change. However, their peak sugar levels after meals, as well as the total amount of blood sugar over the span of 3 hours, decreased significantly. This means that after taking resveratrol, the participants' blood sugar didn't spike as much as it usually would after eating, which is a positive sign for better sugar control. Normally, blood sugar rises after a meal and then gradually decreases as the body's cells use or store the sugar for energy. However, if sugar levels remain elevated several hours after eating, it can indicate insulin resistance, a condition where cells struggle to efficiently absorb sugar from the blood.

Furthermore, the researchers observed improved insulin sensitivity after taking resveratrol. This suggests that cells in the body are becoming more efficient at utilising insulin to regulate blood sugar levels. The researchers also observed a trend towards an improved post-meal reactive hyperemia index, which is a measure of the functioning of the inner lining of blood vessels that plays a crucial role in regulating various cardiovascular functions and maintaining overall health of blood vessels.

These findings suggest that resveratrol may have a positive effect on post-meal sugar levels, overall sugar metabolism, and vascular function (blood vessels) in older adults with impaired glucose tolerance.

Year:

2012

Link:

https://doi.org/10.1093/gerona/glr235

Study type: 

Randomised, double-blind, placebo-controlled trial

Purpose:

To determine the effects of resveratrol on insulin sensitivity and oxidative stress among patients with type 2 diabetes

Dose:

10 mg/day of resveratrol (2 x 5 mg capsules) or placebo

Participants:

19 males previously diagnosed with type 2 diabetes.

Duration:

4 weeks

Results:

The study found an association between 5 mg/day of resveratrol and a significant decrease in insulin resistance. Insulin resistance is a condition where the body's cells become resistant to the effects of insulin, leading to high blood sugar levels, and it is a characteristic feature of type 2 diabetes. The researchers also observed increases in the ratio of phosphorylated protein kinase B (pAkt):protein kinase B (Akt) in platelets (blood-clotting cells) after 4 weeks of resveratrol treatment. This ratio is often used as a measure of Akt pathway activation in cells. The Akt pathway is involved in various cellular processes, including cell survival, growth, and metabolism. 

Year:

2011

Link:

https://doi.org/10.1017/S0007114511000316

Study type: 

Three-arm, two-site pilot, randomised, controlled trial 

Purpose:

To evaluate the safety and effects of resveratrol in combination with exercise in older adults with physical function limitations.

Dose:

500mg/day of resveratrol (1 x 500 mg capsules; 1 x 500 mg placebo capsules) or 1000 mg/day (2 x 500 mg capsules) of resveratrol or placebo

Additional interventions: 

Supervised walking and whole-body resistance exercise training program performed twice a week. 

Participants:

60 older adults aged 65 years and older. A total of 85% of the participants complied with the resveratrol regimen as instructed.

Duration:

12 weeks

Results:

In terms of physical performance, the study found an association between exercise combined with 1,000 mg/day resveratrol supplementation and improved physical and mitochondrial function in older adults. Mitochondrial function involves processes within cells that maintain energy balance and plays a vital role in physical function, especially in the context of exercise and overall fitness.

The researchers observed a relatively low number of possibly related adverse events to the trial. The most common issues were gastrointestinal-related (9 participants) and dizziness. Of these, 2 were in the 1000 mg/day group and 5 were in the 500 mg/day group. Two serious adverse events were reported, but they were found to be unrelated to the trial. 

Overall, the findings suggest that resveratrol supplementation at doses up to 1000 mg/day have potential benefits for both physical and mitochondrial function in older adults, with low number of related, or possibly related adverse events.

Year:

2020

Link:

https://doi.org/10.1016/j.exger.2020.111111

Study type: 

Randomised, double-blind, placebo-controlled trial

Purpose:

To evaluate the effects of short-term resveratrol supplementation on metabolic and safety outcomes in generally healthy overweight, older adults.

Dose:

300 or 1000 mg/day (2 x 150 or 500 mg capsules) of resveratrol or placebo

Participants:

32 overweight adult men and women aged 65 years and older 

Duration:

90 days

Results:

The researchers observed that adverse reactions were consistently low in all groups, including the placebo group. Diarrhoea was the most frequently reported adverse reaction in the 300 mg/day group (33%), and two participants in the 1000 mg/day group withdrew from the study due to gastrointestinal issues. However, there were no statistically significant differences in reported adverse reactions between participants in the treatment group and placebo group.

In addition, the researchers also observed that blood sugar levels remained stable among participants in both of the resveratrol groups. In contrast, participants receiving the placebo experienced a significant increase in blood sugar levels compared to their initial levels over the course of the study.

No significant changes in blood pressure, body weight, or waist circumference were observed in any group.

Year:

2014

Link:

https://doi.org/10.1016/j.exger.2014.05.015

Study type: 

Clinical trial (uncontrolled)

Purpose:

To explore the safety and the effect of resveratrol on the insulin-like growth factor axis, which is a complex hormonal system involving proteins and factors that play a crucial role in regulating growth and development in the body. 

Dose:

0.5, 1.0, 2.5, or 5.0 g of resveratrol (1, 2, 5 or 10 x 500 mg caplets)

Participants:

40 male and female healthy volunteers with an average age of 35-42 years

Duration:

29 days

Results:

The researchers observed that resveratrol was safe, with no serious adverse reactions observed through clinical or biochemical blood tests during the study period and follow-up. Among the 40 participants, some experienced adverse effects, with gastrointestinal symptoms like nausea, flatulence, abdominal discomfort, and diarrhoea being the most common, especially at higher doses (2.5 g and 5.0 g). Most of these events were mild, but some participants at the higher doses experienced moderate symptoms. 

The symptoms, which typically got better during the day but returned after the next dose, was resolved within just 2 days after finishing the 29-day course. No weight loss was observed in any participant, and the treatment did not cause any significant impairment in the participants' ability to carry out their daily activities throughout the study period.

On the basis of these findings, the researchers  recommended that in future intervention studies of resveratrol the daily dose should perhaps not exceed 1.0 g. 

Year:

2010

Link:

https://doi.org/10.1158/0008-5472.can-10-2364

Study type: 

Open-label clinical trial (uncontrolled)

Purpose:

To assess the pharmacokinetic properties (how the body interacts with a drug after it has been administered) and safety of resveratrol following a 500 mg single oral dose. 

Dose:

500 mg of resveratrol tablets

Participants:

15 healthy male and female volunteers, aged 18-55 years

Duration:

Single dose

Results:

No adverse reactions associated with resveratrol were reported during the study. The only moderate-intensity incident observed was a traumatic cutaneous wound, a skin injury resulting from physical trauma like cuts, scrapes, or scratches. This occurred in only one subject in the present study and was not linked to the resveratrol treatment used. Overall, the researchers observed that resveratrol tablets (500mg) were well-tolerated by all participants of the study.

Year:

2016

Link:

https://doi.org/10.3892/etm.2015.2895

Study type: 

Rodent studies 

Purpose:

To evaluate the potential toxicity of resveratrol at different dosages in rats.

Dose:

300, 1000, or 3000 mg/kg body weight/day of trans-resveratrol

Duration:

4 weeks

Results:

Rats administered with 3000 mg/kg body weight per day of resveratrol experienced adverse effects such as increased clinical signs of toxicity, reduced body weights and food consumption. The researchers also observed elevated levels of blood urea nitrogen, creatinine, alkaline phosphatase, alanine aminotransferase, total bilirubin, and albumin, which can suggest problems in kidney and liver issues. There was also reduction in the haemoglobin, hematocrit, and red cell counts, and increased white cell count, which could suggest that the rats' blood and immune systems were affected by the resveratrol treatment, potentially causing anaemia and altering their ability to fight infection. They also exhibited increased kidney weights and clinically significant kidney lesions (damaged kidneys). No histological effects on the liver were observed despite the clinical chemistry changes and increased liver weights in females.

Effects seen in the rats administered with 1000 mg/kg/day of resveratrol included reduced body weight gain (females only) and elevated white blood cell count (males only). White blood cells are a crucial component of the immune system, and an increase in their numbers often indicates that the body is responding to an infection, inflammation, or other health challenges.

No observed adverse effect level was 300 mg/kg body weight of resveratrol.

Year:

2004

Link:

https://doi.org/10.1093/toxsci/kfh263