Checking in On Resveratrol
Resveratrol is in the news again, partly stimulated by research reports from Spain claiming greatly increased resveratrol levels in some wines from Rioja, and partly over-stimulated by a spate of books arguing, more or less, that mega-doses of resveratrol pills can help you live close to forever.
The buzz about this multi-talented compound has been percolating for years -- certainly since the famous “60 Minutes” installment on the French Paradox in 1991. The secret of why people who eat foie gras for snack food have a lower incidence of heart attacks turned out to be red wine consumption, and resveratrol soon emerged as the secret within that secret. Resveratrol’s capabilities as an anti-oxidant were soon established, and in the ensuing years, this little phenolic powerhouse has grown from a mystery ingredient into a major industry.
At one extreme, resveratrol’s reputation has moved from the mere provision of health benefits to the promise of longevity -- perhaps a couple more decades in which to enjoy a few glasses of wine. And at the same time, resveratrol has drawn critics who say it’s not the healthful agent in red wine at all, and in any case, it occurs there in such small doses as to be useless.
Time for a little review.
Ever since resveratrol started to look like a good thing, researchers, growers and winemakers have been trying to figure out ways to get more of it into wine. One high-visibility study detailed by Cornell researcher Leroy Creasy in 2004 found a great deal of variability in the resveratrol content of different wines and among different grape varieties. The numbers made cool-climate Pinot Noirs, such as those from Oregon and upstate New York, look very good -- good enough to prompt Willamette Valley Vineyards to apply successfully to the TTB for permission to list the resveratrol content of its Pinots on the label, along with an explanation of why that number might be of interest.
Vine stress from disease pressure (including Botrytis) was identified as the key factor in explaining heightened resveratrol levels; the vines produced resveratrol as a protective reaction. The problem, says Creasy (now an emeritus professor at Cornell, but still active in the field), is that once the threat goes away, so does the resveratrol, which is remetabolized by the vines. This means harvest timing makes all the difference between grapes full of resveratrol and grapes that used to be full of resveratrol just a week earlier.
These early findings led to a variety of experiments in several countries. Vineyard practices have been tweaked and measured, stress factors besides disease have been looked at, and one Australian producer has marketed wines with resveratrol levels elevated by adding more of the stuff extracted from the pomace of other fermentations. Most recently, a group of producers in Rioja has applied the techniques of nanotechnology, claiming impressive results.
The ongoing, well-funded project in Rioja involves nine wineries (probably the best known in North America being Marqués de Murrieta) working with Avanzare and Dolmar, two high-tech companies with expertise in using nanotechnology in the food and beverage field. The 2008 growing season was their first full-fledged effort, and they announced in July 2009 that their efforts had paid off in Tempranillo-based wines containing more than 25mg per liter of resveratrol -- a substantial increase over previously tested wines.
Neither the press releases from the project nor the accounts in the wine press since have made much mention of the nanotechnology angle, but I was able to discuss this in a series of e-mail exchanges with Julio Gómez, CEO of Avanzare. His first point was that nanomaterials are simply things of a certain size -- from 1 to 100 nanometers (billionths of a meter) in length, a range that includes the molecules that make up a vast amount of the things we put in our mouths, including nearly 100% of the contents of white wine. So there’s nothing controversial about the nano part, which leaves the technology part.
Gómez says that all the materials used in the trials are natural, normal things found and used in vineyards and cellars, all approved by the OIV (International Organization of Vine and Wine) and perfectly legal under Spanish and Rioja wine law: no GMOs, no “engineered” synthetics.
He did not, of course, give me the list of treatments, but he did indicate that the vineyard trials indeed relied on inducing stress to elevate resveratrol, while the cellar treatments increased extraction and combated degradation. The technology comes into play in altering the size of the materials and encapsulating them (again with natural substances), so that they are more easily absorbed and thus more active.
I’m in no position to assess this project in scientific detail, but since it has been carried on with a good deal of public fanfare and numerous scholarly publications along the way, it seems plausible that these folks are on to something -- another fascinating example of pushing the wine envelope with advanced technology, but without GMOs. Whether other wineries will want to take up this approach (with the possibility their customers might think nanotech wines are creepy) is another question entirely.
As is the matter of whether more resveratrol in wine is really a path to health.
Magic bullet or phantasm?
A useful, compact (40-page) booklet summarizing research on resveratrol and health to date has just been published by Matilde Parente, an M.D. and wine lover (Woodland Publishing, $4.95). Parente presents the findings of a number of researchers, shorn of most of the medical-ese, with appropriate cautions along the way.
What I found most interesting, as someone who has not followed the resveratrol saga in great detail, is the broad range of ways in which resveratrol has shown promise: not simply as an anti-oxidant (its most famous capacity), but as an anti-inflammatory, in lowering “bad” (LDL) cholesterol, in preventing blood clots, in preventing cancer, in recovering from and lessening the recurrence of stroke, and possibly in forestalling the onset of Alzheimer’s.
Parente’s overall viewpoint is that the number and range of positive results is quite promising -- though clearly still tentative, given the range of dosages used in different trials and the fact that most were conducted with animals and/or h uman tissue samples, not real live wine drinkers.
That tone of caution does not show up in two other schools of resveratrol thought that are getting attention. One small subset of resveratrol studies has suggested that it might slow aging and increase longevity, in a somewhat roundabout way. Resveratrol can increase the body’s production of sirtuins (proteins that perform a kind of regulatory function), and higher levels of sirtuins have been associated with greater longevity.
It’s a bit of a leap from these findings to the notion that mega-doses of resveratrol, in pill form, can add untold years to your lifetime -- but there are at least a couple hot-selling paperbacks out there making the case, with coupons in the back for ordering resveratrol pills in bulk.
Which gets us into the wonderful, unregulated world of dietary supplements. Both Parente and Creasy have serious concerns about these products, which often take their resveratrol from Polygonum cuspidatum, a Chinese herb that’s not from winegrapes.
Because these products do not go through any equivalent of the FDA process for prescription drug approval, we don’t really know how much (useful) resveratrol is in each pill, or whether its power has been spent by exposure to oxygen, or whether it is metabolized the same way without the presence of alcohol, or whether the extremely high dosages encouraged by this regimen are safe. But a number of websites with intriguing names like alibaba.com will be happy to rush you a supply.
Caution is also not the watchword for some of the critics of resveratrol, the chief name among them being British researcher Roger Corder, author of The Red Wine Diet. Corder’s research suggests to him that the health-affirming compounds in red wine are the procyanidins (tannins) -- not resveratrol at all.
While the resveratrol trail has focused attention on Pinot Noir, Corder puts a spotlight on Tannat, the excruciatingly tannic grape of the Madiran AOC in the southwest of France, where the residents outlive the rest of the French. (My experiences with Tannat have, I think, taken a couple years off my life, but those were not controlled experiments.)
Further, Corder argues that even if resveratrol could be shown to be useful, it would require drinking several cases of wine per day for it to do any good. And he is far from shy about putting forth his opinions in public with a stridency that can be reminiscent of…Tannat.
Corder may well be onto something in drawing attention to procyanidins. If we go back to the epidemiological studies that started all this, it’s worth recalling they correlated health with wine consumption -- not resveratrol pill consumption -- or procyanidin intake. It’s nearly certain that the positive effects of resveratrol -- or of other phenolics -- occur in conjunction with other wine components, including alcohol. It would seem to me there’s room for pursuing the contributions of several component parts here, and no need to insist on a single silver bullet, abstracted from the complex context of wine’s chemical soup.
And as to resveratrol and dosage, the results aren’t all in. Most of the studies described in Parente’s booklet utilized higher levels than are normally found in red wine, which averages somewhere around 1mg per glass. To get up to the 50mg level in some supplements would require prodigious drinking, indeed. But some studies have shown efficacy at lower levels, and some wines deliver much more than 1mg -- the Rioja test wines, for example, apparently come in at about 5mg.
Willamette Valley Vineyards, which continues to test for and label the resveratrol content of its Pinots, has found significant variations among vintages and winemaking techniques. The gap between what can be in the bottle and what’s in the scientific literature isn’t that huge -- and again, back to Rioja, it is by no means fixed.
Which suggests this story is going to keep making news for a while longer.
Tim Patterson writes about wine and makes his own in Berkeley, Calif. Years of experience as a journalist, combined with a contrarian streak, make him interested in getting to the bottom of wine stories, casting a critical eye on conventional wisdom in the process. Contact him through firstname.lastname@example.org.