A healthy diet and regular exercise have long been known to delay or ward off diseases that are more prevalent in old age, such as heart disease, diabetes, cancer, and even cognitive decline. But scientists and consumers have also sought another, less strenuous, way: a pill.
Or even better, a glass of wine. In the early 1990s, research suggested that substances in red wine might explain the so-called French paradox, the observation that wine-loving French people have a low incidence of heart problems while also eating foods rich in saturated fat, such as butter and cheese.
While the world cheered the health-boosting potential of red wine, researchers dug deeper into the components of wine in hopes of discovering its chemical secrets. Among wine’s cache of polyphenols, they discovered the bioactive molecule resveratrol.
Studies, mostly in cell cultures and in animals, showed resveratrol protects against inflammation, oxidative stress, and cancer. The compound even seemingly extended the life span of worms, although the same observation didn’t hold up for mice.
The results were enough to spur demand for resveratrol supplements. Red wine contains only 7 mg/L of the compound, whereas studies showed that positive effects in cells and animals appeared at a level equivalent to 300 mg/L. So suppliers in the supplement industry, many based in China, patented dozens of techniques for producing large quantities of the molecule.
In recent years, a lack of progress in testing resveratrol’s impact on human health has slowed growth in demand for the compound. But that trend may be about to turn around: A new batch of research is now exploring resveratrol’s effects on major age-related diseases in humans, including type 2 diabetes, cardiovascular disease, cancer, and Alzheimer’s. Results from some early Phase II studies suggest resveratrol influences certain molecules in the body that are indicators, or biomarkers, of disease.
Manufacturers say the prospect of positive outcomes from clinical trials has revived interest in new and improved routes to the chemical.
The Swiss biotech firm Evolva has long been planning for resveratrol’s next moment in the sun. In 2012, it acquired a yeast fermentation process for making resveratrol from sugar from Denmark’s Fluxome Science. That year, the market for resveratrol was estimated to be worth about $50 million annually.
“At the time, Fluxome was selling some, but not a lot, of resveratrol,” says Angela Tsetsis, head of Evolva’s resveratrol program. “Evolva took on the technology and really improved upon it to make it more cost-effective.”
In the years since, however, the buzz around resveratrol—and demand for it—has waned. “Like many of these compounds that ebb and flow, resveratrol has been ebbing lately and has been slowing down in the past five or six years,” Tsetsis observes.
So in addition to improving its fermentation route, Evolva has been working to support and highlight new clinical trials looking at how resveratrol might affect blood glucose, metabolic syndrome, and bone health. And last month it gave its resveratrol a brand name, Veri-te, and launched a marketing campaign around it aimed at supplement makers.
Evolva is working to differentiate its product from the many other sources on the market. For instance, other companies extract resveratrol not from wine or grapes, but from the root of a fast-growing shrub called the Japanese knotweed. But plant extraction presents challenges that Evolva doesn’t have to worry about, Tsetsis explains.
Whether resveratrol comes from fermentation, plants, or petroleum, to be useful in a clinical trial it must be of high purity and known origin, points out Fred Stevens, a professor of pharmaceutical sciences at Oregon State University. An off-the-shelf supplement might be only 50% resveratrol, made with a small amount of grape skin extract with added synthetic resveratrol. Using fully synthetic or fermentation-derived resveratrol instead can provide 98% purity, Stevens says.
To be useful in a clinical trial, a large enough dose of resveratrol also has to be administered. Although many supplements offer 100-mg or 250-mg doses of the compound, human studies using these levels tend not to show clinically relevant changes in disease markers. But larger doses of 1 g or greater have had more impact.
One reason high doses may be necessary is that resveratrol is quickly metabolized in humans. The body absorbs only about 25% of the resveratrol dose, and even less—about 1%—escapes the liver to enter the bloodstream, Stevens points out. “However, it is quite likely that any or all of the metabolites of resveratrol have biological activity in their own right.”
Typically, candidate drugs are designed to work on a specific biochemical pathway or receptor, Stevens says. “But who says resveratrol acts on a specific receptor or on a specific pathway?” he asks. Instead, he thinks, the different outcomes that occur with larger doses suggest it affects multiple pathways in the body.
Still, researchers can look for mechanistic clues by studying why plants produce resveratrol in the first place. In grapevines and the Japanese knotwood, resveratrol and other polyphenols are known to trigger a biological response in cells that helps them better cope with oxidative stress resulting from chronic inflammation. Chronic inflammation in humans is thought to be linked to aging-related cardiovascular and neurodegenerative diseases.
In addition to helping cells cope with the stress of inflammation, Stevens says dietary polyphenols may also inhibit inflammatory pathways more directly. One way the body combats inflammation is by activating a class of enzymes called sirtuins, in particular SIRT1, which regulates proteins and genes involved in inflammation and aging. Animal studies suggest caloric restriction diets can extend life span and prevent cancer by activating the SIRT1 pathway.
What really grabs researchers’ attention is that resveratrol, despite some debate about the matter, also appears to activate the same SIRT1 mechanism. That was the lure for R. Scott Turner, director of the Memory Disorders Program at Georgetown University. “I was intrigued by the whole caloric restriction literature,” he says, pointing out that the dietary practice staves off diseases of aging and prevents Alzheimer’s disease in mouse models.
Turner received National Institutes of Health funding for a Phase II clinical trial studying the effect of up to 2 g per day of resveratrol on Alzheimer’s biomarkers in patients with mild to moderate versions of the disease. The randomized, placebo-controlled, double-blind study had 119 participants and lasted 52 weeks.
The biggest and most interesting result was that resveratrol helped stabilize the quantity of amyloid-β in patients’ cerebrospinal fluid, Turner says (Neurology 2015, DOI: 10.1212/WNL.0000000000002035). Amyloid-β is a peptide that forms plaques in the brain, which scientists suspect cause or contribute to Alzheimer’s disease. When people have Alzheimer’s, and as the disease progresses, less amyloid-β leaves the brain to enter the spinal fluid. “We think if you can increase the amount of amyloid-β in the spinal fluid, you can decrease the amount in the brain,” Turner says.
Turner readily admits that his research does not prove that resveratrol’s effects are tied to sirtuins or that the SIRT1 pathway or caloric restriction affects Alzheimer’s disease. And many more famous drug studies targeting amyloid-β formation have all been failures.
He says he hopes to do more studies to show the effect of resveratrol on the brain in people with Alzheimer’s using positron emission tomography scans. But Turner says finding out whether resveratrol slows or delays Alzheimer’s or its cognitive symptoms would require larger Phase III trials that would enroll thousands of patients. Those types of studies are often funded by pharmaceutical companies that have a new, patented molecule that shows promise for treating a disease. Although many firms have patented routes to resveratrol, a molecule that exists in nature cannot be patented.
For his part, Stevens says he would like to see more long-term trials that show a dose response for resveratrol, particularly on biomarkers of metabolic syndrome: insulin resistance and blood glucose levels in people with diabetes and the types and amount of fats, or lipids, in the blood.
Evolva’s Tsetsis claims that more than 1,500 clinical trials using resveratrol were initiated in 2015. “I hope and expect that awareness and respect for resveratrol will grow in 2017, though it won’t happen overnight.” Still, she says, “I’ve seen some upticks. When I start to get queries from bigger brands and companies, that’s how I know that interest is starting to grow.”
American Chemical Society