Is a glass of red wine a day beneficial for the heart?

Question

It has been stated that drinking a glass of red wine per day is good for the heart. There has been a lot of discussion surrounding this issue; two examples are this article from the Guardian and this CNN article.

I am wondering whether there is a marketing campaign behind the claims about red wine, as has been stated about açaí.

Where does the received wisdom about a glass of red wine at night come from? What about the veracity of these statements about red wine? What are some definitive facts (with references) for this debate?

Answer 1

The debate over if red wine had benefits for the heart or other areas of the body focuses around the current debate over the supposed health benefits of the natural phenol Resveratrol.

From the Linus Pauling Institute OSU:

Although resveratrol can inhibit the growth of cancer cells in culture and in some animal models, it is not known whether high intakes of resveratrol can prevent cancer in humans.

Moderate alcohol consumption has been consistently associated with 20-30% reductions in coronary heart disease risk, but it is not yet clear whether red wine polyphenols, such as resveratrol, confer any additional risk reduction.

Notice that they used the word associated in the above quote meaning that there could be any number of other factors that are not measured in scientific study that could influence this correlation (Eg. moderate alcohol consumption may lower stress and lower stress improves heart health?)

Socioeconomic and lifestyle differences between people who prefer wine and those who prefer beer or liquor may explain part of the additional benefit observed in some studies. Several studies have found that people who prefer wine tend to have higher incomes, more education, smoke less, and eat more fruits and vegetables and less saturated fat than people who prefer other alcoholic beverages

Considering the mass media hype surrounding the potential health benefits of red wine, and various press releases by pharmeceutical companies surrounding the supposed benefits, this study has never been published in a peer reviewed scientific journal, so claims made here cannot be taken seriously.

In all, there may be some truth to this, as high dosages of resveratrol had positive effects in lab mice, but so far nobody can really say for sure.

Answer 2

Well, there seems to be some benefit of a low to moderate consumption of red wine to prevent cardiovascular disease. There has been a lot of different studies on this, with different methodologies and results, when that happens, a meta-analyses is warranted, and this question is so polemic that it has a few meta-analyses already. This study, from Chiva-Blanc et al (2013), attempts to make a summary of those meta-analyses of human studies:¹

The beneficial effects of red wine on the cardiovascular system are summarized in Fig. 1, and seem to be greater than other alcoholic beverages, probably because of its high phenolic content. A meta-analysis analyzing 23 studies of the cardiovascular effects of wine and 22 studies of the cardiovascular effects of beer (Di Castelnuovo et al., 2002) observed an inverse association between moderate wine consumption and vascular risk. This meta-analysis indicated an average significant reduction of 32% of overall vascular risk associated with wine drinking. Wine drinkers show a reduced cardiovascular mortality and a lower incidence of non-fatal vascular end points. Beer drinking was also associated with a reduced risk of vascular events, although to a lesser extent than that observed with wine.

There are many possible explanations for this. The authors show supporting studies that wine and other forms of alcohol increase good cholesterol, decrease oxidative stress and inflamation, reduce platelet aggregation and other pathophysiological mechanisms to heart disease, and red wine shows a greater effect than alcohol in other forms (beer, spirits). This is well demonstrated on a table in their article, but I believe I can't reproduce it because those are usually copyrighted. Anyway, this is possibly because both ethanol and poliphenols (which are present in wine, but not in spirits) exert those effects, so yes, red wine seems to be the most beneficial.

But, it is important that they also state that:

Although daily low to moderate alcohol intake is inversely related to CVD, the hormetic behavior of alcohol consumption shows an increased risk of certain cancers, cirrhosis and death from accidents with increasing alcohol consumption (Di Castelnuovo et al., 2010). Three or more drinks per day may increase the risk of heart disease, hypertension, stroke, obesity, hypertriglyceridemia, breast cancer, neurodegeneration, depressive disorders, weakening of bones, suicide and injuries.

In response to that article, Testino et al (2013) wrote a letter to the editor explaining that, although cardiovascular risk may decrease, cancer risk rises even with low consumption, and is generally not advisable:²

For all these reasons, in Australia, the National Heart Foundation explicitly advises against the consumption of red wine and other type of alcoholic drinks for the preventing or treatment of heart disease and WHO suggests that a greater reduction in death from ischaemic heart disease can be more effectively obtained by being physically active and eating a healthier diet than by drinking a low dose of alcohol.

Personally, as a psychiatrist, I would be concerned to make such recommendation because of the addictive properties of alcohol, and the general lack of understanding of people that is not a logical conclusion that, if 1 glass is good for your health, 10 glasses are 10 times as good…

List of references:

1. http://www.ncbi.nlm.nih.gov/pubmed/23408240
2. http://www.ncbi.nlm.nih.gov/pubmed/23831770