What Is Resveratrol? What Are Supplements Used For? Benefits and Risks

Resveratrol is a compound with potent antioxidant properties that occurs naturally in certain plants, particularly red grape skins, and is classified as a polyphenol. It is present in small amounts in foods such as red wine, grape juice, peanuts, mulberries, blueberries and cranberries. In recent years, resveratrol supplements have also become popular in tablet and capsule forms. So what is resveratrol used for, does it have an effect on cancer, and what are its benefits and possible harms?

What Is Resveratrol?

Chemically, resveratrol is a polyphenol in the stilbenoid group (scientific name 3,5,4'-trihydroxystilbene). This compound, consisting of two phenol rings linked by an ethylene bridge, is part of plants’ defense mechanisms. Phytoalexins are compounds of this kind produced by plants against pathogens (fungi and bacteria) and environmental stress. Resveratrol is synthesized especially abundantly in grape skins and seeds; for example, 1 gram of red grape skin is reported to contain approximately 50–100 µg of resveratrol. Because grape skins are included in fermentation during red wine production, red wine contains more resveratrol than white wine (around ~1 mg in an average glass of red wine).

The amount of resveratrol obtained from natural sources is generally low. In contrast, much higher doses can be taken in supplement form. The body rapidly metabolizes and eliminates ingested resveratrol. Laboratory research has shown resveratrol to have antioxidant, anti-inflammatory, antiproliferative (inhibiting cell multiplication) and even estrogen-like effects. Many potential benefits, from cardiovascular health to cancer prevention, have therefore been the subject of scientific research. Below, we discuss resveratrol’s possible effects on human health and current scientific views.

What Are the Benefits of Resveratrol? What Is It Used For?

As a potent antioxidant, resveratrol has the potential for many beneficial effects in the body. What is resveratrol used for? Here are the main potential benefits of resveratrol suggested by research:

• May support cardiovascular health: Resveratrol is thought to protect blood vessels. By increasing vascular flexibility, it may help lower blood pressure. It has also been found to reduce oxidation of low-density lipoprotein (LDL, “bad” cholesterol) and, by reducing blood clotting, to slow clot formation in blood vessels. Through these effects, regular resveratrol consumption has been proposed to help reduce the risk of heart attack and stroke.

• Positive effects on blood sugar and metabolism: Particularly in people with diabetes, resveratrol may help control blood sugar by increasing insulin sensitivity. Some small studies have shown that resveratrol supplements may improve blood sugar levels and insulin resistance. Its potential to support weight control by reducing fat-cell formation and preventing fat storage is also being investigated.

• Brain health and memory: Resveratrol is thought to have possible neuroprotective effects (protecting nerve cells). Its potential benefits in neurodegenerative diseases such as Alzheimer’s have been investigated, based on its antioxidant protection of brain cells from damage and its reduction of inflammation. Although some studies show that resveratrol can cross the blood–brain barrier and favorably affect biomarkers associated with Alzheimer’s disease, evidence of a clear improvement in human memory and cognitive function is currently insufficient. In other words, although it may have potential benefits for healthy brain aging, more research is needed in this area.

• Antioxidant and antiaging effects: By neutralizing free radicals, resveratrol may slow cellular aging. Its antiaging effects are thought to reduce cellular damage that accumulates over time and contribute to healthier aging in the long term. Some laboratory experiments have even found that it extends the lifespan of yeast cells, leading to its marketing as a “youth molecule.” However, it must be emphasized that this longevity effect has not been confirmed in humans.

• Joints and inflammatory conditions: Resveratrol’s anti-inflammatory properties may help reduce pain and inflammation in inflammatory joint diseases such as rheumatoid arthritis and in osteoarthritis. Nevertheless, these effects are generally at the level of supportive treatment.

• Skin health: Through its antioxidant and anti-inflammatory properties, resveratrol may slow skin aging by protecting skin cells from oxidative stress. By reducing collagen breakdown and supporting skin elasticity, it may lessen the appearance of wrinkles. Its antimicrobial effects have also been shown to inhibit the growth of the acne-causing bacterium Propionibacterium acnes and reduce redness/inflammation in acne lesions. Resveratrol is therefore used as an active ingredient in some skin-care products.

• Potential to reduce cancer risk (chemoprevention): Resveratrol has been described as a compound that inhibits cancer-cell growth and shows protective properties against cancer formation in laboratory settings. This has raised hopes that it could help prevent cancer (discussed in detail below).

Although these benefits appear promising, the results of large-scale clinical studies have remained inconsistent or insufficient in most areas. In other words, resveratrol is not a medicine; although findings support possible benefits, these effects have not been established. Some human studies, particularly in heart health, have reported positive results (for example, a slight reduction in blood pressure with regular low-dose resveratrol), but a reduction in all-cause mortality has not been demonstrated. Benefits for diabetes and metabolic syndrome have not been fully proven either. Rather than viewing resveratrol as a miraculous supplement, it is therefore more appropriate to consider it part of a balanced diet and a healthy lifestyle as a whole.

Is Resveratrol Good for Cancer? Its Effects on Cancer

Resveratrol is frequently discussed in relation to cancer. Striking laboratory findings lead many patients and relatives to ask, “Is resveratrol good for cancer?” Let us examine this issue in light of scientific data:

Laboratory and animal studies: In Petri dishes or animal models, preclinical research has shown that resveratrol can have multiple effects against cancer cells. For example, resveratrol can inhibit their proliferation (an antiproliferative effect) and trigger programmed cell death (apoptosis). Its potent antioxidant properties also protect cells from oxidative damage that can lead to cancer. Experiments have even observed that, when given with radiation therapy, resveratrol increases radiation’s effect on tumor cells (a radiosensitizing effect) or protects healthy cells from radiation damage (a radioprotective effect). Some studies suggest that combining it with certain chemotherapy drugs strengthens their effects on tumors and provides protection against chemotherapy’s cardiac side effects. In short, basic science has identified many potentially beneficial anticancer effects of resveratrol in experimental settings.

Human studies and clinical data: Unfortunately, laboratory findings do not always translate into clinical settings. The limited human studies of resveratrol conducted so far have not shown a clear benefit in cancer treatment. For example, a small-scale study in patients with colon (colorectal) cancer was a Phase I clinical trial reporting that high-dose resveratrol might somewhat reduce tumor-cell proliferation. However, another pilot study suggested that resveratrol’s possible benefit may lie in preventing cancer development rather than treating existing cancer. In other words, resveratrol may prevent the development of tumors that have not yet formed, but may be ineffective at shrinking a cancer already present in the body.

A more striking example is a resveratrol study in patients with advanced multiple myeloma (a type of blood cancer). Patients in this study received very high-dose resveratrol supplements (nearly 5 grams daily), but the study was stopped early after serious adverse effects developed, including kidney failure. This result raised concerns about the safety and efficacy of high-dose resveratrol.

Hormone-sensitive cancers and estrogenic effects: Particular breast cancer and prostate cancer cases involving hormone receptor-positive tumors (growing in response to estrogen or androgens) call for caution with resveratrol. Resveratrol is structurally a phytoestrogen, meaning it may exert plant-derived estrogen-like effects. Laboratory experiments have shown that, at certain concentrations, resveratrol activates both estrogen and androgen receptors, mimicking these hormones’ effects. In some cancer cells that grow in response to hormonal signals, this may lead to unwanted stimulation of proliferation (cell multiplication). Put simply, alongside its anticancer effects, resveratrol may carry a risk of stimulating some tumors through an estrogen-like effect. People who have had estrogen receptor-positive breast cancer or have risk factors are therefore particularly advised against uncontrolled use of resveratrol supplements. They should always discuss the decision with their doctors.

In conclusion, regarding cancer: Although research into resveratrol is exciting, current scientific evidence does not support using resveratrol alone as a cancer treatment. Consuming resveratrol-containing foods (such as fruit and vegetables) as part of a healthy diet is, of course, beneficial for cancer prevention. However, it is not appropriate for a cancer patient or high-risk individual to turn to resveratrol pills without consulting a doctor. Ongoing clinical studies may clarify the conditions in which resveratrol could be beneficial. For now, replacing existing cancer treatments with resveratrol or similar supplements would be wrong and dangerous. Cancer patients taking resveratrol supplements must also inform their doctors and use them with the treatment team’s knowledge.

Resveratrol Supplements and Their Use

Although some resveratrol can be obtained from natural foods, the doses obtained this way are quite limited. For example, eating a handful of red grapes or drinking a glass of red wine provides resveratrol in milligram amounts. In contrast, commercially available resveratrol supplements may contain tens or hundreds of milligrams per capsule (usually obtained from Polygonum cuspidatum, or Japanese knotweed root). So how should resveratrol supplements be used, and what should be considered?

First, natural foods should always be the preferred option for safe use. Foods such as grapes, mulberries, peanuts, pomegranates and blueberries provide both resveratrol and other beneficial nutrients. Supplements, however, contain concentrated doses, and the long-term effects of these high doses are not fully known. Scientists cannot yet say that “a particular daily amount of resveratrol in mg is ideal.” There is no definite recommendation or official limit for any resveratrol dose. Small studies have used doses such as 100-300 mg daily, while some research has tested much higher doses (gram amounts). Although short-term use in healthy people at low to moderate doses (for example, 150-500 mg/day) is generally reported to be tolerated, this is not a guarantee of safety.

People considering resveratrol supplements should always consult their doctors. This is particularly important for those with a chronic illness or taking regular medication (see the interactions section below). In pregnant and breastfeeding women, resveratrol’s safety has not been adequately studied; resveratrol supplements are therefore not recommended during pregnancy or breastfeeding. Similarly, they should not be used in children.

Resveratrol is best taken with meals or immediately afterward, because as a fat-soluble compound its absorption may increase somewhat with food. When taking a supplement, ensure the product comes from a reliable brand and, if possible, a regulated outlet such as a pharmacy. As with any supplement, the dose stated on the label should not be exceeded. The idea that “more means greater benefit” is incorrect; on the contrary, high doses can have harmful effects.

Side Effects and Possible Harms of Resveratrol

In general, small amounts of resveratrol obtained from food are considered safe for healthy people and do not cause significant side effects. Resveratrol’s toxicity is in fact quite low. However, high-dose resveratrol or its use in certain susceptible people may cause unwanted effects. The possible harms of resveratrol include the following side effects and points requiring attention:

• Digestive problems: With high resveratrol intakes of around 1-2.5 grams daily, the most common side effects are nausea, vomiting and diarrhea. Abdominal pain, gas and bloating have also been reported. Because doses this high cannot be reached through a normal diet, these effects occur mainly with excessive supplement use. For example, a clinical study in 2016 reported fever and pancytopenia (a decrease in all blood-cell types) in a person taking 1.5 grams of resveratrol daily for 6 months. Long-term high-dose use can therefore cause serious problems.

• Changes in liver enzymes: Very high doses may cause abnormal liver function tests (increased ALT and AST enzymes). People with liver disease in particular should avoid high-dose resveratrol.

• Increased bleeding risk: Resveratrol reduces the adhesion of platelets, which play a role in blood clotting. Taking it may therefore trigger unwanted bleeding in people using blood-thinning (anticoagulant or antiplatelet) medicines. Taking resveratrol supplements with drugs such as aspirin, heparin and warfarin may increase the risk of bleeding. Such combinations must always have a doctor’s approval and supervision.

• Drug interactions (CYP enzymes): Resveratrol may affect the cytochrome P450 enzyme system that metabolizes drugs in the liver. For example, in healthy volunteers taking 1 gram of resveratrol daily for 4 weeks, activities of CYP3A4, CYP2D6 and CYP2C9 decreased, while CYP1A2 activity increased. This theoretically indicates that resveratrol could change blood levels of many drugs metabolized through these enzymes. Carbamazepine is among the specific drugs for which animal data indicate an interaction (resveratrol may increase carbamazepine levels). In short, people taking regular medication should be very careful with resveratrol and consult their doctor and pharmacist before starting a new supplement.

• Hormonal effects: As discussed above, resveratrol’s estrogen-like behavior, its phytoestrogenic property, may be undesirable for some people. Resveratrol use may be inadvisable particularly in hormone-sensitive conditions (estrogen-related conditions such as breast cancer, uterine cancer, ovarian cysts and endometriosis). Since it may adversely affect the course of an existing condition, it should not be used, or should be used under medical supervision with great caution in these people.

Taking these points into account, although resveratrol appears safe for the general population, in high doses or in certain susceptible individuals, harmful effects may occur. In summary, when weighing the benefits and harms of resveratrol, informed and moderate use is essential. If any side effect occurs, the supplement should be stopped and a health professional consulted.

Potential Benefits and Risks of Resveratrol (Summary Table)

Table: A comparison of resveratrol’s main potential benefits and risks. Benefits may occur with appropriate doses under medical supervision, but misuse or excessive use may cause side effects and harm.

Frequently Asked Questions About Resveratrol

Is Resveratrol Good for Cancer?

There are no proven data that resveratrol treats cancer. Although it has been shown to kill cancer cells or slow their growth in laboratory settings, human clinical studies have not identified a direct tumor-shrinking effect. Resveratrol should therefore not be viewed as an alternative treatment for cancer patients. However, its antioxidant and anti-inflammatory properties may contribute somewhat to cancer prevention. In other words, consuming resveratrol-containing foods within a balanced diet benefits general health and may indirectly help reduce cancer risk. Key point: People diagnosed with cancer should not use resveratrol or similar supplements without a doctor’s approval.

Who Should Not Use Resveratrol?

The following groups should avoid resveratrol or exercise great caution: (1) Pregnant and breastfeeding women: It should be avoided during this period because its safety is unknown. (2) People with hormone-sensitive cancer or disease: In particular, those with a history of estrogen-related cancers, such as breast, uterine or ovarian cancer, should not use it without a doctor’s approval (resveratrol may have estrogen-like effects). (3) People taking blood-thinning medication: Resveratrol may be inadvisable because it can increase their bleeding risk. (4) People with serious chronic illnesses or taking continuous medication: People with liver or kidney disease, epilepsy or similar neurological conditions, those taking cholesterol or diabetes medicines, and others should always consult a doctor. In general, anyone in a vulnerable state of health should use resveratrol supplements only if recommended by a physician.

Does Resveratrol Cause Pimples?

There is no information indicating that resveratrol directly causes pimples (acne). On the contrary, its antioxidant and antibacterial properties may even benefit acne-prone skin. Some research has shown that resveratrol inhibits P. acnes, a bacterium involved in acne formation, and reduces skin inflammation. This may help pimples heal more quickly. Resveratrol is indeed used in some acne treatments and cosmetic products. However, everyone is different. Although uncommon, some people may report skin irritation or reactions, particularly with topical (applied to the skin) resveratrol-containing products. This reaction is generally related to other ingredients in the product or overall skin sensitivity rather than resveratrol itself. In conclusion, resveratrol generally does not cause acne; on the contrary, it offers potential support against it. If you notice worsening acne while using a product containing resveratrol, it is appropriate to stop using it and consult a dermatologist.

Does Resveratrol Induce Menstruation?

The term “menstruation-inducing,” popularly used for certain herbal products, means helping to start or regulate menstrual bleeding. Such an effect of resveratrol has not been scientifically proven. In other words, resveratrol is not a substance that directly induces menstruation and is not used to start a delayed period. However, preliminary research suggests potential benefits in some conditions causing irregular periods, such as polycystic ovary syndrome (PCOS). For example, a study in women with PCOS suggested that resveratrol supplements might partly restore menstrual regularity by improving hormonal balance. This may stem from indirect effects on hormonal balance, such as reduced insulin resistance. However, this is early-stage research and cannot be generalized to the wider population. In summary: Resveratrol does not normally induce menstruation. If your period is delayed, the best approach is to consult a gynecologist rather than take supplements on your own.

Can Resveratrol Be Used While Breastfeeding?

During breastfeeding, anything a mother consumes may pass into her milk to some extent and affect the baby. There are insufficient data on resveratrol use in breastfeeding mothers. To err on the side of safety, high-dose resveratrol supplements are therefore best avoided while breastfeeding. For the breastfed baby’s health, it is important that the mother avoid unnecessary or high-dose supplements. Like any supplement needed during breastfeeding, resveratrol should be taken only on a doctor’s advice. On the other hand, low amounts obtained through food (such as occasionally eating grapes or mulberries) have no known negative effect on breastfeeding. The concern here is concentrated resveratrol supplements in pill or powder form. In short, resveratrol supplements are not recommended while breastfeeding.

What Are Resveratrol’s Benefits for the Skin?

Resveratrol may provide some benefits for the skin both when taken orally (by mouth) and when used topically (applied to the skin). Its most notable benefit is protecting skin cells, through its potent antioxidant properties, against damage from ultraviolet (UV) rays and environmental toxins. With regular use, it may therefore help reduce signs of photoaging (spots and wrinkles). Its anti-inflammatory effects may also soothe conditions involving skin redness and sensitivity, such as acne, eczema and rosacea. Scientific studies have also shown that resveratrol slows collagen breakdown and can increase skin elasticity, potentially reducing the appearance of fine lines and wrinkles. Spot-lightening effects have also been studied; by suppressing melanin production, resveratrol has been proposed to help alleviate hyperpigmentation (dark spots). Another benefit is that its antibacterial properties may reduce acne formation by inhibiting harmful bacteria on the skin’s surface. In conclusion, resveratrol is valuable in skin care as an anti-aging (age-defying), brightening and protective ingredient. Serums and creams containing resveratrol are available and are used particularly for nighttime antioxidant care. If taken as a supplement, it will contribute indirectly to skin health, but the effect of products applied directly to the skin should not be expected. If you are considering resveratrol for your skin, consulting a dermatologist to choose a product suited to your skin type is recommended.

Conclusion

Resveratrol is a promising compound available from natural sources and as a supplement. Its antioxidant properties give it potential benefits in many areas, from the heart to the brain and from skin to metabolism. Its effects on cancer in particular are being studied extensively, but current data show that it does not work miracles in cancer treatment. Resveratrol supplements should always be used in an informed way; high doses should not be taken without a doctor’s advice and supervision. Remember that, like any supplement, resveratrol has a supportive role and does not replace healthy living. A balanced diet, regular exercise and medical treatments recommended by your doctor should always form the foundation. Resveratrol is an adjunct that may offer an additional benefit on top of this foundation when used correctly. Wishing you good health...