It is proven: https://www.ahajournals.org/doi/pdf/10.1161/CIRCRESAHA.118.313348

The available evidence is large, strong, and consistent. Better conformity with the traditional MedDiet is associated with better cardiovascular health outcomes, including clinically meaningful reductions in rates of coronary heart disease, ischemic stroke, and total cardiovascular disease.

For the last couple of decades many trials were done with thousands of participants and the results are strong and consistent.

As for wine, results of Predimed study (17k participants) showed that Mediterranean diet reduced mortality by 23%. Mediterranean diet with wine reduced mortality by 33%.

https://academic.oup.com/eurheartj/advance-article-abstract/doi/10.1093/eurheartj/ehag696/8786407

updated and longer GBD analyses published four years later concluded that, among adults older than 40 years, low-to-moderate alcohol consumption was associated with lower all-cause mortality than abstention.3 Likewise, the 2025 report by the U.S. Academies concluded that moderate drinking, up to two drinks per day in men or one in women, was “associated with lower all-cause mortality” with moderate certainty.