About Herbs

Bottom Line: In laboratory studies, resveratrol was found to reduce inflammation and to have anti-tumor properties, but human studies have not been conducted.

A naturally occurring compound in the skins 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.

Clinical trials have not been conducted so far to test the efficacy of resveratrol in humans.

Women who have estrogen receptor-positive cancers should not take resveratrol because it may cause certain cancer cells to multiply.

3,5,4'-trihydroxystilbene

Resveratrol is a polyphenolic compound found in the skins of red grapes. It is also found in peanuts, mulberries, spruce, eucalyptus, and some Chinese herbs. Resveratrol has antioxidant and anti-inflammatory properties as evidenced by its cardioprotective effects. It reduces the oxidation of low density lipoproteins (LDL) and inhibits aggregation of platelets and may offer protection against atherogenesis and coronary heart disease ^{(1) (2)}. In addition, resveratrol enhanced the longevity in preliminary studies of yeast cells ^{(11) (12)}. It was also shown to protect against cisplatin-induced cardiotoxicity via suppression of oxidative stress ⁽²¹⁾.

Several cell culture and animal studies show that resveratrol inhibits proliferation of cancer cells via apoptosis and by exerting anti-estrogenic effects ^{(3) (4) (5) (6)}. However, contradictory data from other studies showed that it acts as a phytoestrogen and could activate genes that are normally regulated by estrogen ⁽⁷⁾ or androgen ⁽⁸⁾. Resveratrol was found to inactivate some enzymes of the CYP450 family in tumor cells ^{(9) (10)} but no clinical trial data verify these effects in humans. Thus, cancer patients with hormone-sensitive diseases, such as estrogen receptor-positive breast cancer and prostate cancer should avoid resveratrol as it may stimulate the proliferation of certain tumor cells.

Resveratrol acts as an antioxidant and inhibits the oxidation of low density lipoproteins (LDL) ⁽¹⁾, the aggregation of platelets, and eicosanoid synthesis ⁽²⁾ and induces platelet nitric oxide (NO) production ⁽¹¹⁾, which may help protect against atherosclerosis and coronary heart disease. It also acts as an anti-inflammatory agent by inhibiting cyclooxygenase (COX) activity ⁽¹²⁾ and by releasing cytokines from macrophages in chronic obstructive pulmonary disease (COPD) ⁽¹³⁾. Laboratory studies show that resveratrol has estrogen-like properties and activates expression of genes that are regulated by estrogen ⁽⁷⁾ and androgen ⁽⁸⁾. Other data from cell culture and animal experiments suggest that it plays a role in cancer chemoprevention during initiation, promotion, and progression of carcinogenesis ^{(12) (14)}. In vivo studies also demonstrate the inhibitory effects of resveratrol on the growth of oral squamous carcinoma cells ⁽⁴⁾, human promyelocytic leukemia cells ⁽⁶⁾, human breast cancer cells ⁽⁵⁾, and neuroblastoma cells ⁽³⁾ resulting from induction of apoptosis and its anti-estrogenic properties. In addition, reduction in breast cancer cell migration and invasion was observed after treatment with resveratrol ^{(15) (16)}. 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 ^{(9) (10)}. Preliminary data from recent experiments in yeast cells suggest that resveratrol may have a role in increasing life span, which it does by activating a set of genes known as sirtuins ^{(17) (18)}.

Upon oral administration, resveratrol is rapidly absorbed in the gastrointestinal tract and undergoes glucoronidation and sulfation in the liver microsomes. After 1.5 h, peak plasma levels of resveratrol were detected ⁽¹⁹⁾. Resveratrol is rapidly excreted; more than 50% of the ingested resveratrol is eliminated in urine in 24 hrs ⁽²⁰⁾.

As resveratrol exhibits estrogen-like properties and activates transcription by estrogen receptor and androgen receptor that leads to stimulation of cancer cell proliferation, patients with hormone-sensitive cancers should avoid resveratrol ⁽⁷⁾.

There is no data from clinical trials to support the beneficial effects of resveratrol in humans.