Grapes on Vine

Polyphenols Have Powerful Effect on Blood Pressure

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Grapes on VineAs a health-savvy consumer, you’ve probably at least heard of metabolic syndrome — a group of risk factors connected to diabetes, heart disease and stroke. It’s not a condition that many doctors discuss with their patients at their yearly physicals, but it’s very real and has very serious implications.

The cornerstone of metabolic syndrome is insulin resistance. Insulin resistance develops when the body does not properly use insulin — the hormone released by the pancreas to move glucose into cells for energy. As a result, the pancreas is forced to secrete even more insulin. This continuous over-secretion of insulin eventually sets the stage for diabetes and heart-related problems.

The five main metabolic syndrome risk factors are:

  1. High blood pressure
  2. High triglycerides
  3. Low HDL (“good”) cholesterol
  4. Raised fasting glucose levels
  5. Waist circumference measurement of 35 inches or more

If you have at least three of these five risk factors, then you may have metabolic syndrome and may be at higher risk for more serious complications.

Heart-Related Risk Factors

Another heart disease-related hallmark of metabolic syndrome is endothelial dysfunction, a condition characterized by narrowed blood vessels, inflammation and pro-thrombotic properties. In fact, it is one of the first signs of atherosclerosis and impending cardiovascular disease.

While all this may seem like doom and gloom, the good news is that researchers recently discovered that one particular type of antioxidant — grape polyphenols — can actually reduce the risk of this and other heart-related risk factors associated with metabolic syndrome.[1]

In general, antioxidants protect the endothelium by stimulating the formation of nitric oxide (NO), a compound that relaxes the blood vessels, allowing blood to flow through more freely. Produced by the endothelium, NO plays a huge role in the prevention of blood clotting. So, when the endothelial lining becomes damaged, NO production suffers, leaving blood vessels susceptible to inflammation and clotting.

Grapes have developed quite the reputation when it comes to antioxidant capabilities. They contain numerous antioxidant polyphenols, including anthocyanins, flavonols and resveratrol. You’ve likely heard of resveratrol by now, especially if you are a lover of red wine, which contains high levels of this powerful antioxidant.

In their study, researchers followed 25 men between the ages of 30-70. All of these men had already been diagnosed with metabolic syndrome. They were divided into two groups — the treatment group took 46 grams of grape polyphenol powder per day, and the control group took a placebo powder. In addition, the researchers asked the men to avoid consuming other polyphenol-rich foods during the study period, including berries, tea, grapes and wine.

The participants consumed their respective powders for 30 days, then underwent a three-week washout period, after which they were assigned the alternative treatment for another 30 days.

After reviewing the results, researchers found that the grape polyphenols significantly improved vascular endothelial function and NO availability, and reduced concentrations of the inflammatory marker plasma sICAM-1 — meaning lower inflammation in the body.

Polyphenols Significantly Lower Blood Pressure

Not surprisingly, when taking the antioxidant-rich grape powder, the participants also experienced a reduction in certain risk factors associated with metabolic syndrome. One of the most notable factors was a significant reduction in blood pressure.

During the grape polyphenol period, the participants had a lower resting systolic blood pressure reading (122 +/- 11 mmHg) versus the placebo period (128 +/- 10 mmHg). This may not seem like a dramatic difference, but a 5 mmHg reduction of systolic blood pressure could result in a 14 percent overall reduction in mortality from stroke and a 9 percent reduction in mortality from heart disease.[2] The participants experienced a 6 mmHg difference, which is even better!

Add the Great Grape to Your Diet

By now, it’s clear that grapes are one of the best ways to get important antioxidants into your body, where they perform some pretty amazing preventative and protective functions.

Aim to eat a bunch of grapes (preferably organic red grapes) every day. Or, if you prefer, enjoy a 4-oz. glass or two of red wine every day. (Be sure to stop at two glasses, though, as too much wine can have more negative effects than positive.)

Your final option is to take grape polyphenols in supplement form. You can easily find a few types, like resveratrol or grape seed extract, at most health food stores. If you’re looking for a high-quality supplement that contains both resveratrol and grape seed extract, you can click here.

[1] Barona J et al. Grape polyphenols reduce blood pressure and increase flow-mediated vasodilation in men with metabolic syndrome. J Nutr. 2012 Sep;142(9):1626-32.


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