A New Frontier in Wine and Cardiovascular Science: From Bias to Biomarkers

 In this episode of Daily Value, we examine the latest research on wine consumption and its relationship to cardiovascular health. Leveraging urinary tartaric acid as an objective biomarker, a recent study (PMID: 39689849) published in the European Heart Journal provides interesting evidence of a J-shaped association between wine intake and cardiovascular outcomes.

Discussion Points:

• Biomarkers and Bias: The role of urinary tartaric acid in providing a reliable objective measure of wine consumption, avoiding the recall and social desirability biases inherent in self-reported dietary studies.
• Mechanisms of Action: The potential cardioprotective effects light to moderate wine intake (are they real?)
• Dose-Dependent Effects: Insights into the J-shaped curve, revealing cardiovascular benefits with light-to-moderate consumption and increased risk with heavier intake.

https://pubmed.ncbi.nlm.nih.gov/39689849/ 

Chapters

• 0:00 Wine Consumption and Cardiovascular Health
• 7:13 Effects of Wine Consumption on Health

Transcript

Speaker 0: 0:00

Hello everyone, welcome back to Daily Value, the podcast where we explore the intersection of nutrition, science and health. I'm William Wallace and today we're looking at new controversial and very interesting research published in the European Heart Journal that examined the connection between wine consumption and cardiovascular health. What is most interesting about this research is that it is the first case cohort study that quantified wine consumption using an actual objective measure, not just a self-reported questionnaire, even though that was used as well. By the way, a case cohort study is a research method used to study the link between a specific exposure, like a behavior or biomarker, and an outcome, like a disease, in this case, adverse cardiovascular events. What I'm going to preface is that this episode is not meant to advocate for alcohol consumption. People like to hop up in a frenzy when you don't immediately talk about alcohol in a negative light. So what I will say is that this episode focuses on data tied to wine consumption specifically. It will look at this research I have mentioned and also reference older studies all tied to wine. What I will say is that the debate rages on as to whether it is ethanol content itself or bioactive polyphenol content of wine that has possibly health-promoting effects at low doses.

Speaker 0: 1:23

Now for the purpose of this study. What exactly is light to moderate drinking? Well, moderate drinking usually peaks up at about one glass of wine per day. At least that'll be the case for our purposes here. In the past, moderate drinking has been said to be in the range of one to two glasses per day. On average, under half a glass per day is considered light. Over one glass per day, and especially over two glasses per day, would be considered heavy drinking.

Speaker 0: 1:54

For decades, low to moderate wine consumption has been linked, actually a fair amount of times, to better cardiovascular outcomes. However, much of this evidence has relied on self-reported data, which is obviously prone to inaccuracies and bias. Intake of alcohol can be often underestimated when using self-reported food frequency questionnaires due to inaccurate recall or even biased perceptions on the social desirability of drinking alcoholic beverages. Actually, and very interestingly, vance et al in 2019 concluded that, because of social desirability factors and reporting bias that people who are heavy drinkers are likely to under-report alcohol intake, and because heavy drinking is nearly always associated with worse cardiovascular outcomes that heavy drinkers being misclassified as light or moderate drinkers, it may actually inflate the risks that come up in research when it comes to light and moderate drinking. So one group of researchers knew that they had to eliminate the subjective bias present in these types of studies as best they could.

Speaker 0: 3:00

What they did was measure an objective biomarker of wine intake in older adults at a high risk of cardiovascular disease from a trial called the PREDIMED trial. The marker they used was urinary tartaric acid. Tartaric acid was selected as a biomarker of wine intake since it's produced mainly in grapes and rarely by other plant species. Tartaric acid does not rely on social desirability or recall. Previous studies have demonstrated clear dose-response relationships between urinary tartaric acid and wine consumption, indicating that it is a reliable marker of actual wine intake. Participants in this trial were observed for nearly 10 years.

Speaker 0: 3:42

So what were the findings? Well, participants with urinary tartaric acid levels corresponding to 12 to 35 micrograms per milliliter, reflecting light to moderate wine consumption, which was 12 to 35 glasses of wine per month so basically up to one glass per day at the highest had a 50% lower risk of cardiovascular events compared to those with lower or higher levels of tartaric acid. Myocardial infarction, in particular, showed the strongest inverse association with higher tartaric acid levels. Interestingly weaker, but still significant associations were observed for those with urinary tartaric acid levels between 3 and 12 micrograms per milliliter, indicating benefits at even lower levels of wine consumption that corresponding to 3 to 12 glasses of wine per month. However, higher tartaric acid concentrations corresponding to heavier wine intake were not linked to reduced cardiovascular disease risk, aligning with the J-shaped relationship often observed between alcohol and cardiovascular outcomes. The J-shaped relationship is common when looking at wine consumption and cardiovascular risk, where some intake is associated not necessarily causal, but associated with reduced risk. But as alcohol intake increases, so too does the risk of adverse cardiovascular outcomes. Although grapes, grape juice and raisins can contribute to tartaric acid levels, these factors were measured and controlled for and the participants really weren't consuming those things, so those were not the reasons for the tartaric acid concentrations observed here.

Speaker 0: 5:22

The results of this research align with several other observational studies and meta-analyses. However, if there is a protective effect from wine consumption, the dose is something that is still up for debate, with findings ranging from three glasses monthly up to one glass daily at the highest, before the right side of the J-shaped curve starts to be seen. Problems with much of the literature on the subject include not taking into account confounding variables like reverse causation and being unable to differentiate between different forms of alcohol. One strength of the recently published study we just talked about was that it was able to exclude other forms of alcohol by combining their questionnaire with an objective marker of wine intake. So what makes wine, particularly red wine, a potential cardioprotective agent? The mechanisms underlying the potential beneficial effects of wine? They still remain uncertain. It's not fully known whether ethanol contributes in any kind of hormetic manner, or if it's partially or wholly attributed to other nutritional components such as polyphenols, Although the safe bet is on the latter, as wines, polyphenols have shown a greater effect compared to other non-wine alcoholic beverages in past research that do not show protective effects.

Speaker 0: 6:43

There are limitations to the current study we just went over. The study population consisted of older adults in a Mediterranean setting, which may limit the generalizability of the findings to other demographics. Furthermore, while tartaric acid reliably indicates wine consumption, it doesn't account for other sources of alcohol or dietary patterns that may interact with any effects of compounds in wine. So what does this mean for you? Well, as I said, I'm not promoting alcohol consumption.

Speaker 0: 7:13

However, if you do enjoy a few glasses of wine each month, you have a relatively mindful and healthy diet, you exercise and so on, then the bit of alcohol consumption from wine may not be having any kind of negative effect on you, and it's possible that it could be providing mild positive benefits, although, if they were, they would be marginal at best, given I'm certain you take care of yourself through proper diet, sleep and exercise. Obviously, excessive consumption not only diminishes benefits, if any, but also introduces additional risks. That has been reliably recorded, regardless of your drink of choice. This study also underscores the importance of objective biomarkers like tartaric acid in nutritional research. By moving beyond self-reported data, then we can gain clearer insights into the complex relationships between diet and health. That's it for today's episode of Daily Value. If you found this episode insightful, don't forget to subscribe and share. Until next time, stay curious, stay informed and, as always, stay healthy.