May 23, 2019

expert reaction to study on a molecule in red wine and blood pressure

Research published in Circulation demonstrates that a molecule found in red wine causes a drop in blood pressure.

Prof Roger Corder, Emeritus Professor of Experimental Therapeutics, Queen Mary University of London, said:

“I have been pushing back for many years against associating resveratrol with any effects of red wine. In fact, most red wines have undetectable levels of resveratrol. I published correspondence in Nature in 2003 highlighting the divide between doses of resveratrol being used experimentally compared to the amounts present in red wine. But the urban myth that resveratrol might explain the health benefits of regular red wine consumption has persisted. The dose here of 320 mg/kg in mice can be considered equal to treating a human with 15 to 20 g resveratrol. This amount is ridiculous and in red wine terms equivalent to more than 3000 litres of wine.

“Regarding the embargoed paper, the effects described seem more likely to be because of the very high concentrations of resveratrol being used rather than any relevant biological effect which could be used in drug development. These type of “off-target” biochemical modifications of proteins are more likely to have negative effects on health than any benefit. The effects on blood pressure are quite small. So, I am astounded this paper made it through the referee process at Circulation. There’s no attempt to show the threshold dose of resveratrol for effects on blood pressure. It could be as little as 5 mg/kg (even though that still doesn’t bring it down to the amount possible to gain through drinking wine). Experimentally the lowest dose that reduces blood pressure should have been found and then the researchers should have carried out experiments using that dose to provide insights into the mechanism. Is this mechanism important? Based on the data presented it is difficult to reach any satisfactory conclusions.”

Dr Bob Patton, Alcohol Researcher & Lecturer in Clinical Psychology, University of Surrey, said:

“These scientists have demonstrated that under laboratory conditions, and using a very high dosage, that resveratrol can significantly lower blood pressure in mice. The authors are quick to point out that this effect has not been tested in human studies. While resveratrol is often associated with red wine, it is a naturally occurring compound that is found (in very small quantities) in many different fruits and nuts, not just grapes. To match the effective dosage in the study, you would need to drink about 1000 bottles of wine, which is of course impossible.

“Excessive alcohol consumption is associated with increases in blood pressure, and this can lead to cardiovascular problems like heart attacks and strokes, so it’s a good idea to reduce it. Relaxing with a glass of red is one way to unwind at the end of the day, but on its own that is not going to help tackle hypertension; losing weight, taking regular exercise and lowering your stress levels are three of the best ways to do this.”

 ‘Blood pressure-lowering by the antioxidant resveratrol is counterintuitively mediated by oxidation of cGMP-dependent protein kinase’ by Prysyazhna et al. was published in Circulation at 00:01 UK time on Thursday 23 May 2019.

Declared interests

Prof Roger Corder: “I am the author of The Wine Diet and have investigated other mechanisms by which red wine polyphenols can improve cardiovascular function, particularly focusing on a group of grape pip tannins called procyanidins. Others have shown grape seed extract in doses that can be achieved by drinking tannic red wines that are rich in procyanidins do lower blood pressure in patients, and this has got nothing to do with the mythical properties of resveratrol.”

Dr Bob Patton: “No conflicts of interest.”