A few weeks ago, I sent out a tweet and shared on Facebook an article from CBS News describing a new study which found that red wine may reduce blood pressure in men, but only if it is non-alcoholic. Sure, this makes sense to me: component of red wine (particularly polyphenols) have been shown to have many health benefits, including cardiovascular health benefits, and alcohol has been shown to have negative health effect when consumed heavily.
Reading the article further, some of the limitations of the study were addressed, which put into question for me the validity of the results. Specifically, there was no control group for this study. That right there is a major red flag, and for anyone who has ever worked in research, you know you must have a control group in order to make ANY sort of comparison or come to any sort of conclusion. The study also mentioned that it is well known that blood pressure goes up after one stops drinking alcohol, even if they weren’t drinking that much to begin with, so the overlap between this possible increase and the next phase of the experiment could have muddled the results.
Dissatisfied with these huge limitations in the study protocol, I wanted to see if any other studies have focused on this idea of non-alcoholic or at least low alcohol wines, and if they are any better for us than wines with the “standard” amount of alcohol present. As luck would have it, I stumbled upon an article that was published in June of this year that examined the effects of low alcohol wines on cardiovascular health. Unlike the aforementioned article, this article was performed on rats instead of humans, which makes the comparison an indirect one, but potentially important nonetheless.
In addition to blood pressure benefits, the polyphenols in red wine have also been shown to have protection against ischemia/reperfusion events (that’s doctor talk for “heart attacks”). Though it is known that these polyphenols have protective effects against heart attacks, it is not yet known the proportion to which this effect is attributable to the alcohol or the polyphenols in red wine. The study presented today aimed to answer that question by comparing antioxidant and cardio-protective properties of wine with “standard” levels of alcohol, and wines with lowered levels of alcohol.
French red, rosé, and white wines with 12% alcohol by volume were used in this study. In order to create the same wine with lower alcohol, alcohol was removed via the lirisation process, which the authors confirm did not alter the chemical composition of the wine, other than the alcohol level.
Antioxidant characteristics of each wine were measured using the oxygen radical absorbance capacity (ORAC) assay with fluorescein.
Male Long Evans rats(age not reported) were utilized for this study. There were
a total of 4 general treatment groups to which these rats were assigned: Control group (no wine); 12% v/v wine group; 6% v/v wine group; 12% v/v alcohol extract group; or 6% v/v alcohol extract group. The alcohol extract groups were to compare to the red wine and control groups in order to determine if the alcohol contributed to changed in cardio-protective properties, or if it was something else attributable to the non-alcohol components of the wine. Reminder: red, rosé, and white wines were tested for each alcohol level.
Alcoholic solutions were created by adding one part red wine or alcohol extract to 7 parts drinking water. This corresponds to about 2 glasses of wine per day, relative to body weight. Rats were fed these red wine, alcohol, or water solutions for 10 consecutive days, then rats were harvested for analysis.
Rat cardiac function was monitored and analyzed by measuring heart rate, left ventricular developed pressure, and coronary flow. If you’re curious to know, left ventricular developed pressure is calculated as the difference between left ventricular end systolic pressure and left ventricular end diastolic pressure. Rate pressure product was calculated by multiplying the heart rate and the left ventricular developed pressure at a given time point.
All rat hearts underwent 30 minutes of ischemia (closing of the blood vessels—like a clot causing a heart attack) and 30 minutes of reperfusion (opening on the blood vessels—short term recovery from the heart attack).
- Red wine contained higher levels of antioxidants than white or rosé wines (to be expected).
- The reduction of alcohol to 6% v/v in wines did not alter the antioxidant levels of any of the wines.
- Giving rats wine or alcohol extract prior to ischemia/reperfusion did not alter the functional character of the rat hearts.
- Treatment with wine at 12% v/v and 6% v/v alcohol improved left ventricular developed pressure function after reperfusion compared with controls.
- No differences were seen in cardio performance after ischemia/reperfusion in 12% v/v and 6% v/v alcohol wines.
- Treatment with wine at 12% v/v and 6% v/v alcohol significantly improved rate pressure product compared with the controls.
- Treatment with alcohol extract did not improve any of the cardiac functions measured compared with the control group.
What does this all mean?
This was a pretty brief study, and the results are fairly straight forward. According to the authors of the study, it is the first to show that chronic and moderate consumption of red wine for 10 days in rats is protective against ischemia/reperfusion (recall: heart attack).
Bringing the focus back to the low-alcohol quality of some of the wines, the results of the study show that lower alcohol wines do not affect the antioxidant properties of the wine, nor do they provide any extra cardiovascular benefit that wines with twice as much alcohol provide. This result is seemingly inconsistent with the results of the blood pressure study described in the introduction to this post.
The study results indicate that while red wine solutions provide cardio-protective benefits to rats, alcohol extracts alone do not. By eliminating all other components of the wine, the result indicates that alcohol is not responsible for providing any positive cardiovascular benefit but rather the remaining components of the wine (likely the polyphenols) provide this benefit.
So which study is correct?
I certainly cannot say that this study disproves the earlier study, since many of the methods were different between each publication. First of all, this study used rats, while the study mentioned earlier used actual humans. Second, that this study did use controls (good!!), while the previous study mentioned had no controls (bad!!). Third, the study mentioned previously just monitored blood pressure, while this study measured several cardiac function parameters. Of course I can’t directly compare these two studies, but it certainly gets one thinking! Neither study mentioned how getting rid of the alcohol altered the aroma/flavor/quality of the wine, nor do I have time to elaborate more now on that important topic.
However, I can say with confidence that this study provides results that call into question the validity of the first study, or that perhaps the entire story is much more complicated than a simple “yes or no” answer. Maybe the level of alcohol in wine doesn’t matter to some groups, but does matter to others. Maybe it has certain positive health benefits with some groups, but not with others.
One thing about medicine is that it’s complicated: ridiculously complicated. Sure, we can say that drinking a handle of vodka isn’t going to be good for any individual, but can we say with certainty that two glasses of wine are or are not good for each individual? No, because each every human body is different. Take antidepressant medications, for example: one antidepressant medication will work famously for one patient, but when given to another patient, it may not have any effect or even have an opposite effect (*note: I qualify this example based on my first hand experience working in the Neurology clinic at my place of employment*).
My guess is that wine behaves in the same way. For some people, moderate wine consumption will be great for their overall health, whereas for other people, wine may not be as beneficial. The complicated nature of both wine and the human body will make many blanket statements about the health benefits of wine near impossible. We have seen it happen so much already, with one study claiming one result and another coming out a few weeks later saying the opposite.
While I believe this type research is very important and should continue to be funded and performed, each individual person should certainly talk things over with their doctor if there is any concern whatsoever about possible positive or negative health benefits of the wine that they consume. Of course, for me, I enjoy drinking wine for reasons other than potential health benefits, so regardless of what study results come forth, I likely will not alter my consumption habits.
I’d love to hear what you all think of this topic, and of the topic of the health benefits of wine in general. Please leave your comments and engage in the discussion!
CBS article: http://www.cbsnews.com/8301-504763_162-57508191-10391704/red-wine-may-reduce-mens-blood-pressure-but-only-if-its-non-alcoholic/ Last accessed 10/01/2012.
Article presented today: Lamont, K., Blackhurst, D., Albertyn, Z., Marais, D., Lecour, S. 2012. Lowering the alcohol content of red wine does not alter its cardioprotective properties. South African Medical Journal 102 (6): 565-567.