Thickening of the arteries, or atherosclerosis, is a disease that is often associated with complications of heart attack and stroke. It is caused by LDL cholesterol (low density lipoprotein) which enters into the inner lining of the arteries which causes vascular oxidative stress. This oxidative stress occurs via the production of too many reactive free radicals that canâ€™t be controlled by the antioxidative species that naturally reside in the body. When unable to control simply by altering diet and exercise habits, a way to reduce the oxidative stress (and thus the occurrence of too many harmful free radicals) is needed to reduce the risk of atherosclerosis and ultimately those cardiovascular events that are triggered by this disease.
As you all know by now, if you read this blog or have read one of the countless research articles related to the topic, that wine (particularly red wine) is loaded with polyphenols, which originate in the skins and seeds of the grape though a small fraction originates from the oak barrels that the wines are fermented and/or aged therein. Red wine typically has higher levels of polyphenols present, since red wine goes through a maceration step where the skins and seeds are left in the juice for a period of time, allowing the extraction of greater levels of polyphenols. White wines do not undergo this maceration step, nor do the skins and seeds typically remain in contact with the juice for any reason (of course there are exceptions), thereby resulting in a marked reduction in polyphenols in the finished white wine.
Polyphenols are known to have high antioxidant capacities, a fact by which has been studied over and over again in the literature. In studies of red wine and its effects on cardiovascular health, several mechanisms for possible protection have been described. Some studies showed that the cardio-protective nature of the wine is related to the high antioxidant capacities of the polyphenols present in the wine, while other studies claim that the polyphenols are acting in a more anti-platelet or anti-inflammatory fashion, which increases vasodilatation (i.e. opening of blood vessels) and improves cardiac function.
The study presented today aimed to examine the antioxidant activities of red wine in the rat model, while simultaneously determining whether or not results found in vitro (i.e. outside of the body, or in other words, in test tubes and petri dishes) correlated with what is found in vivo (i.e. inside the body). The latter is important for if it were found that in vitro results did not correlate with in vivo results, then making any assumptions or formulating implications for human health from in vitro studies would be much more difficult without an in vivo component.Methods
The wines used in this study were: 1) a Chilean Syrah; 2) a Brazilian Cabernet Sauvignon; and 3) an Argentinean red blend. After purchase, the bottles were opened, put into test tubes, and stored at -80oC until ready for use in the experiment.
Rats were randomly split into 5 groups: 1) control rats fed a regular diet; 2) rats fed a high fat diet and 770-1360ÎĽL water; 3) rats fed a high fat diet and 800-1380ÎĽL of red wine with low antioxidant activity; 4) rats fed a high fat diet and 790-1170ÎĽL of red wine with intermediate antioxidant activity; and 5) rats fed a high fat diet and 820-1340ÎĽL of red wine with high antioxidant activity. The dose of wine was adjusted every week (for a total of 4 weeks) according to the body weight of the rats.
After the 4 week experiment, blood and liver samples were taken from the rats and analyzed for the following: plasma fatty acid composition, malondialdehyde concentration, plasma antioxidant activity, antioxidant enzyme expression (superoxide dismutase, catalase, and glutathione peroxidase), and antioxidant enzyme activity.
â€˘ Rats fed a high fat diet showed increased levels of malondialdehyde in their blood plasma.
â€˘ Rats fed a high fat diet ate less food than the control diet group, though there were no differences in weight gain between the groups.
â€˘ Rats supplemented with high antioxidant wine had the lowest malondialdehyde levels in the liver and plasma antioxidant activity compared with all other groups and the low antioxidant wine group, respectively.
â€˘ A correlation was found between in vitro antioxidant activity measurements in the wine and in vitro measurements in the blood plasma of rats.
â€˘ Catalase and glutathione peroxidase were highest in rats supplemented with the low antioxidant activity wine.
â€˘ The only difference in enzyme activities was: superoxide dismutase was higher in the high antioxidant wine group compared with the medium antioxidant wine group.
â€˘ The only differences in plasma fatty acid profiles were the following: 1) palmitoleic acid was higher in the high antioxidant wine group compared with the medium antioxidant wine group; and 2) cis-13,16-docosadienoic acid was higher in all wines groups compared with the non-wine control.
â€˘ Rats supplemented with the low antioxidant wines had increased activity in all enzymes measured compared with rats supplemented with the high antioxidant wine.
â€˘ Trans-resveratrol, quercetin, and anthocyanidin levels were highest in rats supplemented with high antioxidant activity wines.
The authors of this study claimed that based on the results, rats supplemented with wines with high antioxidant activities were better able to protect against blood plasma and liver oxidative stress than wines with lower antioxidant activities. They also suggested that resveratrol, quercetin, and anthocyanidins play an important role in the protection against oxidative stress due to their high abundance in the rats supplemented with the high antioxidant activity wines. It was also noted that higher levels of trans-resveratrol were associated with lower levels of malondialdehyde, which further supports the idea that this compound plays a major role in protection against oxidative stress in the body.
The take-home given by the authors was that since there are differences between rats and human in regards to their response, further studies should only focus on wines with medium to high antioxidant activities, because wine with low antioxidant activities may not provide much protection against oxidative stress and atherosclerosis than would be ideal.
Iâ€™d love to hear what you all think about this topic. Do you really care about the antioxidant capacity of wine? Does this factor into your buying behavior when it comes to purchasing wine? Or, is this all just interesting for scienceâ€™s sake and youâ€™re going to drink wine anyway knowing you might be getting a nice little cardio-protective bonus? Please feel free to leave comments!
Source: Macedo, L.F.L., Rogero, M.M., GuimarĂŁes, J.P., Granato, D., Lobato, L.P., and Castro, I.A. 2013. Effect of red wines with different in vitro antioxidant activity on oxidative stress of high-fat diet rats. Food Chemistry 137: 122-129.