Claims that a chemical component of red wine can stave off Alzheimer’s disease, combat cancer, and prevent heart disease have piqued the interest of both scientists and health-conscious consumers for decades.

But what is resveratrol, really?

Does research support these claims? How much wine, exactly, would a person have to drink to reap the benefits?

Resveratrol, a polyphenolic compound found in grape skins, peanuts, cocoa, and some types of berries, is marketed as a wonder supplement. Studies of its potential benefits date back to 1939, but no definitive evidence of its effectiveness in people yet exists.

Time magazine has a story about red wine’s potential to slow Alzheimer’s disease. And Brooks Ayers, a controversial figure on the television show Real Housewives of Orange County, said he’s been taking the supplement intravenously to treat his disputed cancer diagnosis.

The supplement, which can be taken orally or intravenously, has been studied widely. However, few high quality clinical studies using human subjects exist. That means that many of the health benefit claims touted by supplement makers and wine sellers may not be accurate.

“The only way to know whether resveratrol affects humans is to conduct human studies,” said Victoria J. Drake, Ph.D., of Oregon State University’s Linus Pauling Institute in an email to Healthline. Drake manages the Micronutrient Information Center, which keeps a close eye on research related to vitamins, minerals, and phytochemicals.

In order to receive Food and Drug Administration (FDA) approval as a substance that reliably benefits a specific health condition, clinical studies called randomized controlled trials must demonstrate that a health benefit exists.

Essentially, a substance must be proven to work better than a placebo in a tightly controlled experiment to be marketed as beneficial.

“At present, studies in humans are very limited, and priority is given to developing ways to increase resveratrol absorption and bioavailability in humans before exploring its putative health benefits,” said Drake.

The problem of absorption and bioavailability may sound complicated, but it’s actually quite simple.

The body recognizes resveratrol as something foreign and then quickly metabolizes and gets rid of it. This means that very little resveratrol actually sticks around long enough after eating those grapes to truly be of much benefit.

“The biological significance of resveratrol found in our diet has been largely overrated,” said Drake. “Supplements may contain anywhere from less than 1 to 500 mg of resveratrol per tablet or capsule, but it is not known whether there is a safe and effective dosage for chronic disease prevention in humans.”

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What Science Does Know

The suspected advantages of resveratrol are under investigation. Those benefits include its role as an antioxidant, its potential to delay Alzheimer’s, its cardiovascular health benefits, and its promising role in improving lipid and glucose levels in people with type 2 diabetes.

Preclinical research, studies of cells and animals, has demonstrated that the compound may inhibit tumor growth and prevent clogged arteries.

Studies conducted on humans also show that resveratrol supplements were associated with improved cholesterol levels and maintenance of blood sugar levels, a promising finding for type 2 diabetes treatments.

Resveratrol may also play a role in delaying the effects of Alzheimer’s.

Research by Dr. R. Scott Turner, director of Georgetown University Medical Center’s Memory Disorders Program, found that participants who took resveratrol supplements had improved daily functioning, less brain atrophy, and stabilized biochemical markers of Alzheimer’s disease. The study’s findings, from Phase 2 of a 3-phase randomized controlled trial, set the stage for a new approach to Alzheimer’s treatment.

“This is a new way to develop treatments for Alzheimer’s disease – targeting mechanisms of aging instead of targeting amyloid [a protein associated with the disease] directly. Aging is the number one risk factor for Alzheimer’s,” said Turner.

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The Take Away

Resveratrol supplements aren’t regulated by the FDA and the compound has only had limited human studies.

So, critics are dubious of the “wonder drug” reputation of resveratrol and studies like Turner’s that show isolated results in participants taking resveratrol in high doses.

Turner’s Alzheimer’s study, for example, gave participants daily doses containing the equivalent of 1,000 bottles of red wine. Phase 3 of Turner’s clinical trials could begin in a year.

There are resources for determining the quality and purity of over the counter supplements, but drinking a glass of wine a day or eating a few blueberries is not likely to provide enough resveratrol to prevent diabetes, ward off Alzheimer’s, or clean out your arteries.

Nonetheless, the research into Alzheimer’s disease and type 2 diabetes, two of today’s most expensive and debilitating diseases, is promising.

And resveratrol does appear to halt tumor growth in animals.

While it’s no panacea, resveratrol does demonstrate potential to treat and slow some disease processes.

Future human trials may reveal just how much.

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