Grapevine & Wine 06/02/2012

Wine and resveratrol: are the benenifts fictional?

Dipak Das, University of Connecticut, falsified his results. Moreover, the concentration of resveratrol in wine is negligible. Almost anything is known on the influence of this molecule on human health. At the moment there are no proofs of beneficial effects. We discuss this issue with the scientist Francesco Visioli

The news arrived a couple of weeks ago. Media largely neglected it, but we can’t. It is necessary to establish the truth to avoid repercussions and misunderstandings. This is particularly important in issues concerning human health and nutrition, since sometimes the enthusiasm of reporting news shadows the right dose of skepticism. Well, this week we speak about the news that the recent research about resveratrol y Dipak Das was fake. We discuss with Professor Francesco Visioli, scientist at the Universidad Autónoma de Madrid, Madrid Institut for Avdanced Studies (IMDEA).

Francesco Visioli
Recently the media have reported the news, first published in Nature, that Dr. Dipak Das of the Connecticut University, author of many publications about resveratrol, falsified his data. Is this true?
Yes, it is. It has been proven that Dipak Das counterfeited data in at least 23 publications over the years. The US Office of Research Integrity (ORI) demonstrated many inconsistencies in Das’s works.

So everything we have been told about resveratrol is false?
No, it isn’t. Dipak Das is just one of the many scientists working on resveratrol. But this is the right occasion to make some points clear about this molecule.

What are you referring to?
The first point it should be clear that at the moment we know very little about the relationship between resveratrol and health. There are no evidences of beneficial properties of this molecule available nowadays. In brief, we have no idea what are the effects – if any- of resveratrol in supplements.

Why do you refer to vitamin supplements and not to wine?
The resveratrol concentration in wine is negligible. And this is a goof thing. As a matter of fact, resveratrol is produced by grapes in response to the attack of fungi. If the grapes have been treated properly, almost no resveratrol should be found in the final product.
If you look at the labels of vitamin supplements, you will see that resveratrol is extracted by Polygonum cuspidatum there, a Chinese tuber.

Are there other issues about resveratrol our readers should be aware of?
Yes, indeed. Resveratrol doesn’t enter blood circulation after it has been eat with food. It is degraded in the gut, the liver and the blood. Hence, the quantity that arrives in cells is almost zero. Most of the studies presented by media are pointless, since they show the effect of this molecule on cells in culture when exposed to concetrations way higher than what observed in humans. Moreover, variations across species do exist. What has been observed in mice was not present in monkeys. And in over twenty years of work on humans, no effects have ever been shown. This induce me to think that what are missing are not experiments, but results.

And why don’t they publish negative results?
This is a good question. It is what is called publication bias. Nobady is interested in negative results. Did you ever see a journal headline saying: “the molecule x is ineffective” ? Moreover, there are very strong economic interests over resveratrol. Just think to David Sinclair (that worked for long time on resveratrol and that now distances himself from Dipak Das) that sold his company to GSK for 720 million dollars. And that soon after published that rapamicin and not resveratrol increases the life expectancy of mice.

So, what do you think about resveratrol?
I think that we don’t enough about it to say anything. I also think that it is so popular because people is happy to hear that red wine is good for our health. Maybe this is true, but for sure this is not because of resveratrol, as I said. As far as we know, resveratrol doesn’t have any significant biological activity. However research goes fast; perhaps they will find something in the future.
Also the notion that it activates sirtuins, a class of molecules linked to longevity, has been recently demonstrated to be wrong. As a comparison, we know more about hydroxytyrosol, which is also approved by EFSA.

The extol hydroxytyrosol which is found in olive oil…
Yes, the hydroxytyrosol that can be found in extra virgin olive oil. The most used food fat in Mediterranean countries.

And why is hydroxytyrosol less known than resberatrol?
Because the countries leader in scientific research are USA, UK and Japan. These countries don’t use the extra virgin olive oil or they consider it as an exotic product. This is the reason why hydroxytyrosol is less popular and funded; on the contrary, red wine has the appeal of sin.

And, as a scientist, what do you think about Dipak Das?
I think that most probably he is not the only one. Now everybody distance themselves from him, but consider that it has been calculated that there are over 80,000 people in treatment for cancer with drugs based on fake data. I don’t know if this is true; but if it was it would be an immoral thing. Being a scientist, like many of your readers, is a difficult life, always full of frustration. But we need to get used to it and to keep behave even when things go in the wrong direction. We can’t rule over nature: we try to discover her secrets, not to force her to our will.

They could accuse you to be defeatist and sacrilegious! Now you get resveratrol amiss as well…
No, I don’t. We don’t know almost anything about it, hence we should be careful when we speak to the public. This holds for resveratrol, but also for many other issues concerning food. These are very difficult researches, and the risk to confuse nutrition with pharmacology is high. This gives wrong hopes to people.
Something I really think is immoral is to declare to newspapers: “Resveratrol works against cancer”. If it was true, why aren’t oncologists using it? Why don’t they say this face to face to patients just out the surgery room?

So, which is the take-home message for our readers?
Let’s try to read critically everything published, knowing that we don’t know.

di Luigi Caricato