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Drinking a small amount of wine each day may protect the heart, according to a new study of Spanish people following the plant-based Mediterranean diet, which typically includes drinking a small glass of wine with dinner.

In a group of people over 60 at risk for heart disease, drinking one-half to one glass of wine a day reduced the risk of having a cardiovascular event such as a heart attack or stroke by 50% when compared to people who drank no wine.

However, this protective effect disappeared in people who drank more than one glass per day, according to senior study author Dr. Ramon Estruch, who studies cardiovascular risk, nutrition and aging at the University of Barcelona.

“This study examines the importance of moderate wine consumption within a healthy dietary pattern, such as the Mediterranean diet,” said Estruch, an internist in the internal medicine department of the Hospital Clinic in Barcelona, in a statement.

“Until now, we believed that 20% of the effects of the Mediterranean diet could be attributed to moderate wine consumption; however, in light of these results, the effect may be even greater,” he said.

However, critics say the study doesn’t consider the well-known health harms of alcohol, including wine.

“While the study suggests that low to moderate wine consumption may lower CVD (cardiovascular) risk, it is not an all clear to crack open a bottle of red wine,” said Tracy Parker, senior dietitian at the British Heart Foundation, who was not involved in the study.

“It is well-documented that excessive alcohol consumption is harmful to heart health,” Parker said in a statement. “Drinking too much alcohol increases the risk of heart and circulatory conditions, such as high blood pressure and vascular dementia, as well as liver problems and certain cancers.”

In addition, many people don’t accurately measure their wine pours, experts say — what should be a small 4-ounce glass of wine could easily become a 6-ounce or even 9-ounce pour.

“People often say that ‘wine is good for the heart’ but we also know too much wine is ‘not good for the heart’,” said Paul Leeson, professor of cardiovascular medicine at the University of Oxford, who was not involved in the study.

The research, published today in the European Heart Journal, is part of an ongoing Spanish study investigating the impact of a Mediterranean diet on people at risk for heart disease. The 1,232 participants in the current study had type 2 diabetes or risk factors such as smoking tobacco, high cholesterol and blood pressure, were overweight or obese and/or had a family history of heart disease.

At the beginning of the study, people were asked about their typical food and drink and were required to provide a urine sample used to measure tartaric acid — a chemical excreted in urine that is naturally found in grape products such as wine. After a year on the Mediterranean diet, the urine test was repeated — if grapes or wine were consumed within the last five or so days, the test would pick it up.

“By measuring tartaric acid in the urine, alongside food and drink questionnaires, we have been able to make a more accurate measurement of wine consumption,” Estruch said.

Grapes, and therefore wine, do contain large amounts of tartaric acid, yet using that as a marker is not without concern, said Kevin McConway, emeritus professor of applied statistics at the Open University in Milton Keynes, United Kingdom, who was not involved in the study.

“A lot of the variability in tartaric acid could arise from other things, such as the respondents not all being honest about how much they drank, or by there being a certain length of time between the self-reported alcohol consumption and the tartaric acid measurement, or because the tartaric acid levels are also affected by consumption of other foods or some processes in the body,” McConway said in a statement.

It is also important to note that the study’s results only show an association, not causation, Leeson said.

“There may be other things that people who consume this amount of wine did in the study that helped reduce their risk,” Leeson said. “For one thing, the study was performed in people who were also eating a heart-healthy diet. Maybe the health advantages of a glass of wine are only seen when being drunk alongside a plate of Mediterranean food?”

There are much healthier ways to protect one’s heart and overall health than drinking, such as eating a balanced diet and getting regular exercise, as well as maintaining a healthy weight and not smoking, Parker said.

Naveed Sattar, a professor of cardiometabolic medicine and honorary consultant at the University of Glasgow in Scotland who was not involved with the study, advised against drinking wine or any alcohol for good health.

“I would strongly urge people to drink as little as they can do if they wish to be healthier,” Sattar said in a statement. “The wine paradox is a myth and this article adds nothing whatsoever new to what is already known .”