Research Shows Wine Enhances the Impact of the Mediterranean Diet

FIVIN compiles scientific information on the relationship between wine and health and, in 2023 was a co-organiser of the Lifestyle, Diet, Wine & Health Congress held in Toledo, Spain, which brought together the world’s scientific experts on wine and health.

It’s hard to imagine a more contentious place to be than in the scientific trenches arguing about the health benefits of wine, at a time when new research methods are casting doubt on the idea that moderate wine consumption can have any health benefits at all.

But Prof Estruch — whose titles include Senior Consultant at the Internal Medicine Department of the Hospital Clinic (Barcelona), Professor at the Barcelona University, Member of the Board of Directors of the CIBER Obesity and Nutrition, Institute of Health “Carlos III” (ISCIII), Government of Spain and Scientific Director of the Mediterranean Diet Foundation at Barcelona — believes that there are clear benefits to consuming moderate amounts of wine, particularly in conjunction with the Mediterranean diet.

Largely based on the eating habits of southern Italy, southern Spain and Crete, the Mediterranean diet is credited with the ability to lower heart disease and other chronic conditions. Key components include legumes, vegetables and plenty of olive oil, plus some fish, cheese, yoghurt, and red meat. And, of course, wine.
 

A major European study

Prof Estruch says that, 15 years ago, it was still possible to get a European grant to study whether wine had any beneficial impacts or not.

And he was curious about something. Although he knew about the “bad face of alcohol”, he also knew of the J-curve, a curious effect seen in many observational studies, where people who consume moderate levels of alcohol seem to have better health outcomes than people who either don’t drink, or who drink too much.

Prof. Estruch compared the effects of alcohol alone, with that of wine, “and I was surprised that even ethanol at low doses has good effects on some biomarkers like oxidative stress and also inflammation,” he says. “But we realised that wine, because it has polyphenols, is better than ethanol alone.”

In 2003, he and colleagues launched an ambitious trial, called Predimed,  to look at the impact of the Mediterranean diet on heart disease in high-risk individuals. A total of 7,447 people aged between 55 and 80 were enrolled; 57% were women. One group was assigned a Mediterranean diet with extra-virgin olive, another group ate the Mediterranean diet with extra helpings of nuts, and the last group ate the diet without any extras.

Funded by the Spanish government, the trial ended in 2010, and the results were published in the prestigious New England Journal of Medicine: “Among persons at high cardiovascular risk, a Mediterranean diet supplemented with extra-virgin olive oil or nuts reduced the incidence of major cardiovascular events.”

“The main finding was that if you follow a traditional Mediterranean diet, you can decrease cardiovascular death by 30%,” says Prof Estruch. “And because this was a randomised clinical trial, the level of evidence is the highest.”

Alcohol or something else?

As it turns out, it seems both the ethanol and the polyphenols in wine appear to have a role to play. The alcohol in wine  seems to help the body to unlock and absorb the polyphenols that are present in the wine, as well as in other foods like olive oil and vegetables. Prof Estruch says the research suggests that around “20% of the effects of the Mediterranean diet have to be attributed to wine”.

As to which polyphenols are most beneficial, Prof. Estruch says the mix is more important than the individual compounds, just as the overall diet — “a mix of vegetables, fruits, fish and nuts and so on” — is more important than a specific ingredient. He does add that oleuropein, a polyphenol found in olive oil, is “a special polyphenol” with “a very high anti-inflammatory effect. Maybe there are some polyphenols in wine that have a more anti-inflammatory effect than others.”

Prof Estruch says he was surprised by his own results. “I got into this field from analysing alcoholic people, and I was so shocked by the effects of red wine,” especially its impact on inflammation and oxidation. “I thought that red wine would be good, but I was shocked at how good it is for health. And the high effect of maybe one or two glasses of wine with a meal is unbelievable for me.”

He’s also clear that this effect cannot come from grape juice, not only because there’s no alcohol present, but because of the high sugar content. “Sugar, especially in liquid, is not good for health,” he says. “The best is the regular wine that is a mix of ethanol plus polyphenols.”

Moderation is the other key. “If you drink a lot, your blood pressure is going up,” but when people consumed small amounts of red wine, their blood pressure decreased.
 

Moderate consumption isn’t the whole story

The days when an organisation like FIVIN could spread the word about this kind of research without pushback are over, because a new wave of research has called the health benefits of wine into serious question. Not only that, but in January 2023, the World Health Organisation said there was “no safe level” of alcohol consumption.

Prof Estruch disputes this, and says scientists have enough evidence to conclude that moderate drinking has a health effect, “but if you put moderate drinking, especially wine, under the umbrella of the Mediterranean diet, the health [effect] is much higher. And if you practise exercise and so on, the effect is much better. But I think that the highest power of these is diet.”

When it comes to the WHO declaration, Prof. Estruch has some scepticism about the methods used. First, the declaration was based on the Global Burden of Disease work, and he says the results were confounded because the general consumption of alcohol across the world was dropped into the mix, and the specific way that alcohol is consumed is extremely important.

“Context is very important in the effects of alcoholic beverages,” he says. “Drinking gin outside of meals is not the same as drinking wine with meals. The frequency of consumption is also important.”

He says another problem was that some studies considered weekly consumption of alcohol, rather than daily consumption. “It’s not the same. If you have one drink, seven days a week, it’s not the same as seven drinks in one day. That’s binge drinking.”

Funding difficulties

Prof Estruch says he believes it’s important to tell the truth about alcohol, from how dangerous it is when abused — not just the well-known effects like liver damage, but also the heightened risk of breast cancer and other diseases — but also its apparent protective effects when consumed at low levels, particularly in conjunction with a healthy meal. “It’s important to disseminate the results, because people can decide to drink or not to drink but with the information for this decision.”

Even so, there are still many unknowns about alcohol, but Prof Estruch says investigating the subject is difficult.

“One of the problems we have now is that it’s very difficult to get funds to investigate the effects of alcohol on health, because the government doesn't want to put money into this issue.”

It is possible to get money to study wine in the context of something else, like the Mediterranean diet, but “you cannot put ‘I want to analyse wine and health’.” And even then, finding research money isn’t easy. “You have to knock on a lot of doors.”

More evidence on the way

Prof. Estruch has recently finished another trial, called Predimed-Plus, whose goal is to “analyse the effects of not only diet, but lifestyle. That could be diet, exercise and the way of living and so on, to see if this has bigger clinical outcomes.”

Predimed-Plus, a six-year randomised control trial, enrolled nearly 7,000 people, and fed them a diet that was similar to that of Predimed, except that one group had extra physical activity. The study not only looked at cardiovascular health, weight and diabetes, but also at the incidence of cancer. While some preliminary papers have been published, the full results will only be available later this month.

Prof Estruch says the news is good on all fronts, and bolsters the case for drinking moderate amounts of wine, but in the context of the Mediterranean diet.

Of course, most people don’t drink wine in conjunction with meals — or follow the Mediterranean diet. Even the Spanish have abandoned it. As the newspaper El Pais put it, “Spaniards eat just as badly as people do in other countries”.

And there are even questions over whether people under 35 should consume the diet without the wine, given the harmful impact of alcohol on younger people. One of Predimed's lead researchers, Prof Miguel Martínez-González, is currently undertaking a €2.5m study at the University of Navarra to better understand the role played by wine.

But there is a growing groundswell of support for the diet itself, from enthusiastic media coverage of its benefits, to the Spanish government throwing institutional support behind it, seeing it as not just a way to improve the health of the population, but also as part of its cultural heritage.

Once the Predimed-Plus results are published, there is likely to be even more noise about it. What people who want to adopt it need to know is that there are two critical ingredients: olive oil. And, according to Prof Estruch, small amounts of wine. At least for older people.