While the antioxidants in red wine are believed to contribute to better cardiovascular health, researchers in Spain say the grapes used to make it contain significant levels of fiber that also assist in strengthening the heart. They have found that the fiber and antioxidants in the Tempranillo grape seem to reduce blood pressure and cholesterol better than other sources of dietary fiber, specifically oats and psyllium.
The study, which is published in the July/August issue of the journal Nutrition, is a followup to earlier experiments from the same team that found that drinking 300 ml of red wine a day could contribute to the daily recommended intake of soluble fiber in Spain.
For their latest research, the scientists, based in the Department of Metabolism and Nutrition, Instituto del Frío, Madrid, wanted to evaluate the effects of a fiber-rich red-wine grape on the cardiovascular systems of both healthy volunteers and those with high cholesterol.
The researchers picked Tempranillo because they found that the variety has high levels of dietary fiber compared to white varieties. They recruited 27 women and 16 men, between the ages of 20 and 45, from the community at the University Complutense in Madrid, where their lab is based.
The subjects were randomly selected and nonsmokers, and blood tests revealed that 25 had high blood pressure. Thirty-four of the subjects were asked to consume a Tempranillo-based dietary fiber product developed at the Institute in 1998.
According to the study, the grape supplement contained 5.25 grams of dietary fiber and 1,400 mg of antioxidant polyphenols, such as procyanidin and cathechin. By way of comparison, the American Heart Association recommends 25 to 30 grams per day of fiber in order to keep the heart healthy and regulate metabolism. According to the study, the average intake of a Westerner is likely to be around the 20 grams per day mark, with the Spanish intake normally much lower.
After the trial period, the team examined blood samples and found that cholesterol levels were up to 14 percent lower in healthy individuals who took the supplement and nearly 19 percent lower in those who had high cholesterol going into the research. The control group's cholesterol levels remained the same. Blood pressure was also reduced in both fiber supplement groups by 5 to 6 percent. Triglyceride levels improved as well.
These results were also found to be "more pronounced" than the findings of a USDA-conducted meta-analysis, published in a 1999 issue of the American Journal of Clinical Nutrition, of 55 studies examining similar effects of oat and plantain-based psyllium fibers.
Co-author Jara Pérez-Jiménez explained that the results of non-wine Tempranillo on the blood are promising because "the lack of alcohol effectively makes it suitable for those people who want to take the beneficial polyphenols present in grapes and wine, but cannot or do not want to drink alcohol."
"This is particularly interesting for the reduction of blood pressure," she continued. "Although red wine itself has shown in several studies a beneficial effect in relation to blood plasma, this has not been observed for blood pressure, since it is well-known that alcohol intake [normally] increases blood pressure."
Pérez-Jiménez adds that a regular intake of a grape-based dietary fiber supplement with a balanced, healthy diet may show a significant and positive effect in the reduction of cardiovascular risk factors.
"This may also be applied to people with cardiovascular problems, however, we cannot propose it yet as an alternative to heart pills for those people who already suffer such problems, rather as a complement to their medical therapy."