A Glass of Wine a Day keeps the Doctor Away… Or Does it?

“A glass of red wine a day is good for your heart.” This has been a common saying most people have heard, most of the time while someone is pouring themselves a second glass. Physicians from Hippocrates to Galen prescribed wine as medicine. As much as some of us would like to believe this claim, the biology and psychology behind it tell a different story (Rathee and Jain 2020) .

The biology: what happens when you drink wine?

Wine is not simply just alcohol; it’s a complex mix of compounds intricately put together to create different flavours, colours and aromas (Buljeta et al. 2023). Research has really dove into the health benefits surrounding the compounds of flavonoids and resveratrol which are types of polyphenols (Buljeta et al. 2023). Grapevines make resveratrol to fight fungal infection, and because red wine ferments with the grape skins (Puddey et al. 1998) .  

Resveratrol works by signalling for the cells that line blood vessels to release nitric oxide. In doing so this relaxes the arteries and discourages clotting which can be seen in figure 1.

\Wine polyphenols can also slow the oxidation of LDL cholesterol which is a beginning step in plaque formation (Weiskirchen and Weiskirchen 2016). 

The body complicates this. Ethanol acts as a pro-oxidant that can cancel out wine’s antioxidants, and many red wine polyphenols are too large for the gut to absorb well (Stockley 2015). Dose is the bigger problem. Red wine has around 2 mg of resveratrol per litre and it has been seen through animal research that you would need to reach around a gram a day to get actual effects (Stockley 2015). That would be around 500 litres of wine every single day.

The psychology: why did we believe it?

The “French Paradox” was the main reason the idea came to be. France had been seen to have low rates of heart disease death even though their diet consisted of saturated fats and wine seemed to be the reason. The evidence is strictly from observational studies and hence cannot be used to prove causation.

The claim stuck because of psychological factors. We like to strictly look at evidence that helps our views which is called confirmation bias. So when we hear that wine could be possibly beneficial we only look at claims that help support that belief. Wine also carries a “health halo,” linked with meals, Mediterranean living and sophistication rather than heavy drinking (Ferrières 2004) . In the late 1990s, the wine industry lobbied for US labels inviting drinkers to ask their doctor about wine’s health effects (Ferrières 2004) .

The drinkers themselves differ too. Compared with beer and spirits drinkers, wine drinkers tend to be more educated, wealthier and more active, are less likely to smoke, and report fewer psychiatric symptoms (IARC Working Group on the Evaluation of Carcinogenic Risks to Humans 2010). Any of these could make wine look protective. Many studies also counted people who quit because they were already sick as “non-drinkers.” When a 2023 meta-analysis corrected for these flaws, low-volume drinking no longer showed a significantly lower risk of death (Cook et al. 2024) .

So, is it good for you?

Wine’s compounds have genuinely interesting biology, but it hasn’t been shown to produce healthier hearts, and Canada’s 2023 guidance links even three to six drinks a week with a higher risk of several cancers (Canadian Centre on Substance Use and Addiction 2023). The lesson isn’t that wine is poison. It’s that a plausible mechanism plus a flattering belief is not proof. Sometimes what makes wine drinkers healthy isn’t in the glass, but who’s holding it.

References 

Buljeta, Ivana, Anita Pichler, Josip Šimunović, and Mirela Kopjar. 2023. “Beneficial Effects of Red Wine Polyphenols on Human Health: Comprehensive Review.” Current Issues in Molecular Biology 45 (2): 782–798.https://doi.org/10.3390/cimb45020052.

Canadian Centre on Substance Use and Addiction. 2023. Canada’s Guidance on Alcohol and Health: Final Report. Ottawa, ON: Canadian Centre on Substance Use and Addiction.https://www.cancercare.mb.ca/pdflink/en/22a3de4e-5027-11e6-816f-005056a734b7/Canadas-Guidance-on-Alcohol-and-Health-Final-Report.pdf.

Cook, W. K., W. C. Kerr, Y. Zhu, S. Bright, C. Buckley, C. Kilian, A. M. Lasserre, L. Llamosas-Falcón, N. Mulia, J. Rehm, and C. Probst. 2024. “Alcoholic Beverage Types Consumed by Population Subgroups in the United States: Implications for Alcohol Policy to Address Health Disparities.” Drug and Alcohol Review 43 (4): 946–955.https://doi.org/10.1111/dar.13819.

Ferrières, Jean. 2004. “The French Paradox: Lessons for Other Countries.” Heart 90 (1): 107–111.https://doi.org/10.1136/heart.90.1.107.

IARC Working Group on the Evaluation of Carcinogenic Risks to Humans. 2010. “Alcohol Consumption and Ethyl Carbamate. 1. Exposure Data.” IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, no. 96. Lyon: International Agency for Research on Cancer.https://www.ncbi.nlm.nih.gov/books/NBK326559/.

Klabunde, Richard E. 2018. “Nitric Oxide.” Cardiovascular Physiology Concepts. Revised January 5, 2018. https://cvphysiology.com/blood-flow/bf011.

Puddey, Ian B., Kevin D. Croft, R. Abdu-Amsha Caccetta, and Lawrence J. Beilin. 1998. “Alcohol, Free Radicals and Antioxidants.” Novartis Foundation Symposium 216: 51–62; discussion 63–67, 152–158. https://doi.org/10.1002/9780470515549.ch5.

Stockley, C. S. 2015. “The Relationships between Alcohol, Wine and Cardiovascular Diseases: A Review.” Nutrition and Aging 3 (2–4): 55–88.https://doi.org/10.3233/NUA-150052.

Weiskirchen, Sabine, and Ralf Weiskirchen. 2016. “Resveratrol: How Much Wine Do You Have to Drink to Stay Healthy?” Advances in Nutrition 7 (4): 706–718.https://doi.org/10.3945/an.115.011627.