
Resveratrol is a polyphenolic compound found in many botanical products. Red wine is a natural source of resveratrol as it is rich in grape skin and seeds. However, resveratrol is usually consumed as a dietary supplement for its purported antioxidant and anti-inflammatory properties. It is also marketed as an anti-aging supplement based on the findings that it prolongs the life span of yeast cells (1) (2). This effect has not yet been demonstrated in humans.
Resveratrol is thought to have cardioprotective effects. Earlier studies found that it reduces the oxidation of low density lipoproteins (LDL) and inhibits aggregation of platelets and may offer protection against atherogenesis (3) (4). Consumption of wine or a resveratrol-rich grape supplement is associated with reduction in risk of cardiovascular disease (5) (6) and may help promote health of the circulatory system (7) (8) (9).
Resveratrol can increase insulin sensitivity in diabetic patients (10) (11). However, clinical studies on the effect of resveratrol in controlling metabolic syndromes in obese subjects yielded mix results (12) (13). In vitro and animal studies show that resveratrol inhibits proliferation of cancer cells via different mechanisms (14) (15) (16) (17) (18) (19). It may also protect against chemotherapy-induced cardiotoxicity (19) (20). Further clinical studies are needed to confirm these effects in humans.
External application of a resveratrol containing gel reduced the symptoms of acne (21).
While resveratrol is generally safe, high doses can cause gastrointestinal side effects, such as diarrhea. Resveratrol inhibits CYP450 enzymes (22) (23) and may increase the risk of adverse effects of certain drugs.
Resveratrol acts as an antioxidant and inhibits the oxidation of low density lipoproteins (LDL) (21), the aggregation of platelets, and eicosanoid synthesis (4). It also induces nitric oxide (NO) production (24) (25) and increases arterial blood flow (8). These actions may contribute to resveratrol's purported cardiovascular health benefits.
Resveratrol acts as an anti-inflammatory agent by inhibiting cyclooxygenase (COX) activity (26). It has been shown to decrease C-reactive protein, tumor necrosis factor, and to increase anti-inflammatory interleukin-10 and intercellular adhesion molecule-1 in humans (5).
Resveratrol decreases oxidative stress and improves insulin sensitivity by increasing protein kinase activities (10) . It decreases circulating insulin-like growth factor-1 (IGF-I) and IGF-binding protein-3 (IGFBP-3) levels (27) which may account for its anti-diabetic effects in humans.
Preliminary data suggest that resveratrol increases the life span of yeast cells by activating sirtuins (1) (2). Recent study shows it inhibits human Sirt3 and stimulates Sirt5, in addition to Sirt1 (28).
In vitro and animal studies show that resveratrol has anticancer activities. It inhibits proliferation of cancer cells via apoptosis and by exerting anti-estrogenic effects (14) (15) (16) (17). However, contradictory data from other studies showed that it acts as a phytoestrogen and could activate genes that are normally regulated by estrogen (18) or androgen (19).
Trans-resveratrol appears to decrease methylation of the tumor suppressor gene RASSF-1alpha in women at increased breast cancer risk (29). In addition, reductions in breast cancer cell migration and invasion were observed after treatment with resveratrol (30) (31). Resveratrol growth factor heregulin-beta1 (HRG-beta1) -mediated Matrix metallopeptidase 9 (MMP-9) expressions in human breast cancer cells (30).
Resveratrol may help reduce prostate tumorigenesis through a reduction in the prostatic levels of mTOR complex 1 (mTORC1) activity and increased expression of SIRT1 and (32). Another study demonstrated that resveratrol modulates steroid hormone-dependent pathways to inhibit prostate cancer cell growth. However, resveratrol also increases angiogenesis and inhibition of apoptosis in vivo (19).
In an animal model, resveratrol down-regulated p21 and up-regulated cyclin E leading to S-phase accumulation and apoptosis in neuroblastoma cells (14). Resveratrol also inhibited the enzymes CYP1A1, CYP1A2, and CYP1B1 in tumor cells. This may be one of the mechanisms by which it exerts anti-tumor effects as some of these enzymes are known to be involved in the activation of procarcinogens and toxins (22) (23).
The protective effect of resveratrol against doxorubicin-induced cardiotoxicity is due to up-regulation of SIRT1-mediated p53 deacetylation. (20). It also protects against cisplatin-induced cardiotoxicity through the suppression of oxidative stress (19).
Resveratrol can be consumed as a purified dietary supplement or as a constituent in red wine. The pharmacokinetic profiles may vary depending on the intake. Food and high-fat meals can decrease and delay its absorption (33) (34). Upon oral administration, resveratrol is rapidly absorbed in the gastrointestinal tract and undergoes glucuronidation and sulfation in the liver microsomes mainly to resveratrol-3-O-sulfate, resveratrol-4'-O-glucuronide, and resveratrol-3-O-glucuronide (27). Metabolic conjugation is affected by microbiota. (35). Peak plasma levels can be detected 1.5 hr after oral intake (36). Resveratrol is rapidly excreted; more than 50% is eliminated in urine in 24 hrs (37).
The aglycone forms of resveratrol are better absorbed than the glycosides (37). Micronizing resveratrol may help improve its absorption (38).
Because resveratrol exhibits estrogen-like properties and activates transcription by both the estrogen and androgen receptors that lead to stimulation of cancer cell proliferation, patients with hormone-sensitive cancers should use caution (18).
Poulsen MM, Vestergaard PF, Clasen BF, et al. High-Dose Resveratrol Supplementation in Obese Men: An Investigator-Initiated, Randomized, Placebo-Controlled Clinical Trial of Substrate Metabolism, Insulin Sensitivity, and Body Composition. Diabetes. 2012 Nov 28. [Epub ahead of print]
In this study, 24 obese, healthy men were randomized to receive 500 mg trans-resveratrol or placebo, thrice daily, for 4 weeks. Glucose turnover and insulin sensitivity were assessed before and after the treatment. There was no significant decrease in insulin sensitivity, the primary outcome measure, in either group. There was also no change in the endogenous glucose production and the turnover and oxidation rates of glucose. Further resveratrol did not affect blood pressure; resting energy expenditure; oxidation rates of lipid; ectopic or visceral fat content; or inflammatory and metabolic biomarkers.
Reseveratrol may not be effective against metabolic disorders.
Bottom Line: In laboratory studies, resveratrol was found to reduce inflammation and to have antitumor properties, but human studies have not been conducted.
A naturally occurring compound in the skin of red grapes and other botanicals, resveratrol has been shown to reduce inflammation. It also has antioxidant properties and may help to protect against atherosclerosis (thickening of arterial walls) and heart disease. Animal studies have shown that resveratrol has the ability to prevent certain cancer cells from dividing. Human studies on its anticancer effect are lacking.
Metabolic Disorders:
In this study, 24 obese, healthy men were given 500 mg trans-resveratrol or placebo, thrice daily, for 4 weeks. Glucose turnover and insulin sensitivity were assessed before and after the treatment. There was no significant decrease in insulin sensitivity in either group. There was also no change in the endogenous glucose production and the turnover and oxidation rates of glucose. Resveratrol also did not affect blood pressure, fat content, or inflammatory and metabolic biomarkers.
Patients with hormone-sensitive cancers should use caution when taking resveratrol because it may cause certain cancer cells to multiply.