Diet and Nutrition; Heart

5 foods rich in heart-healthy polyphenols

Diet and Nutrition; Heart

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Several studies suggest that diets rich in foods containing polyphenols, such as red wine and dark chocolate, could potentially offer some protection from the development of heart disease.

There isn’t much dispute about the health benefits of apples. After all, “an apple a day keeps the doctor away,” right? But what about red wine, chocolate, and various oils and spices?

As it turns out, chemical compounds called polyphenols are found in all of these items. Polyphenols occur naturally, can have antioxidant properties, and are more generally found in fruits, vegetables, cereals, dry legumes, chocolate, and some beverages, oils, and spices. Research suggests that diets rich in foods containing polyphenols could potentially offer some protection from the development of heart disease, neurodegenerative disease, cancer, and diabetes.

Specific to cardiovascular disease, polyphenols may offer protection by improving the function of the inner lining of the heart and blood vessels (endothelium), increasing protective HDL cholesterol (the good cholesterol), decreasing LDL cholesterol (the bad cholesterol), and promoting anti-platelet and anti-inflammatory activity. Whether protection from the development for heart disease is due to antioxidant properties is uncertain. There are clinical studies yet that track changes in disease burden and patient longevity to evaluate the true benefit of antioxidants (even though the word “antioxidant” can make people feel good!).

Let’s discuss what we do know about the health benefits of five polyphenol-rich foods:


Both the skin and flesh of apples are believed to have health benefits. Research is ongoing to distinguish which part(s) of the apple deliver specific benefits, such as the lowering of CVD risk.

A recent study measured the effect apple skin had on the endothelial function, as measured by flow-mediated dilation of the heart and blood vessels (enabling blood to flow smoothly, which lowers CVD risk). It is known that apple skin, rather than the flesh, contains high amounts of the polyphenol called flavonoid. Thirty study participants ate the equivalent of two apple skins twice a day or pureed apple flesh twice daily. Significant improvement in flow-mediated dilation was observed after consumption of the apple skins versus the apple flesh, at one hour and two hours after consumption, as well as four weeks later. These results suggest flavonoids in apple skin may have the potential to improve endothelial function right after you eat them as well as over time.

Another study measured the effect apple consumption had on lipids, vascular function, and other CVD risk markers. Forty volunteers with mildly elevated cholesterol consumed two whole apples daily or a (control) sugar apple beverage with the same number of calories. Whole apple consumption, unlike the control beverage, was found to significantly decrease total cholesterol, LDL cholesterol, and triglycerides, and increase flow-mediated dilation – all of which are associated with a lowering in CVD risk. These results suggest eating polyphenol-rich apples is beneficial for individuals with mildly elevated cholesterol.

Bottom line: Whole apples contain potentially protective substances, even though research is ongoing to determine whether the protective substance is the flavonoid in the skin, the soluble fiber in the flesh, or a combination of factors. Regardless, it’s safe to say that apples are one of nature’s great fast foods.

Red wine

Red wine and dark grape juice contain multiple polyphenols such as resveratrol, catechin, epicatechin, quercetin, and anthocyanin, which synergistically lower CVD risk, such as the risk of coronary heart disease. Research has found that the polyphenols decrease inflammation and stimulate the production of nitric oxide, which signals the arteries to expand, thus increasing blood flow. It also reduces insulin resistance and decreases the oxidative stress of LDL cholesterol, thus possibly reducing the deposition of cholesterol in the arteries. Correspondingly, red wine is one of the components of the heart-healthy Mediterranean diet.

Bottom line: Red wine is good for your heart, although it is not recommended you start drinking alcohol if you don’t already drink it. And if you do drink alcohol, do so in moderation, which is defined as one drink per day for women and two drinks per day for men. One drink is equal to 5 ounces of wine, 12 ounces of beer, or 1.5 ounces of liquor. It is always a good idea to discuss alcohol consumption with your doctor if you are on medications.


Several studies have examined whether chocolate provides heart-healthy benefits. For example, previous research suggests that eating small amounts of dark chocolate with about 70 percent cocoa reduces cardiac events, while a more recent study (funded by a chocolate company) suggest that flavanols (a sub-class of flavonoids) in cocoa may improve vascular function and cholesterol levels in healthy individuals, at least in the short term.

In this study of healthy middle-aged men and women, small but statistically significant improvements were observed in flow-mediated dilation, blood pressure, and cholesterol levels after consumption of a cocoa-flavanol-fortified drink (900 mg) twice daily for four weeks.

Another recent study (funded by a cocoa company) showed that healthy men and women lowered their total cholesterol, LDL cholesterol, and triglycerides, and increased their HDL, after consumption of a cocoa powder containing 220 mg of flavanols and 92 mg of epicatechins for four weeks.

More definitive research is ongoing through the Cocoa Supplement and Multivitamin Outcomes Study (COSMOs) trial, which is evaluating the effect of 600 mg of cocoa flavanols (versus a multivitamin) on the risk of developing heart disease, stroke, or cancer.

Bottom line: Chocolate may have some health benefits, but this doesn’t mean you should eat a large chocolate bar every day. Most experts recommend no more than 1 ounce per day of chocolate since each ounce has about 170 calories. Chocolate also contains caffeine and theobromine, both of which can interact with medications. Finally, individuals who experience migraines report chocolate as a possible trigger.

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Extra virgin olive oil should be certified by the North American Olive Oil Association or the California Olive Oil Council.

Olive oil

There is strong evidence olive oil, in particular extra-virgin olive oil, helps prevent heart disease, strokes, metabolic syndrome, and some cancers by protecting against oxidative damage. It also boosts the proliferation of white blood cells and cytokines, which supports the immune system. Extra-virgin olive oil has the highest concentration of polyphenols (compared with other olive oils) because it is produced by natural extraction and is the least processed form of olive oil. Extra-virgin olive oil is also a key component of the heart-healthy Mediterranean diet.

It is common to find olive oil products falsely labeled as ‘extra-virgin’ when, in fact, they are actually diluted with cheaper vegetable oils, which limits or eliminates the health benefits. Always check labels to ensure the olive oil is certified by the North American Olive Oil Association, the California Olive Oil Council, the Extra Virgin Alliance, or the USDA. 

Extra-virgin olive oil also has a shelf life. Use it within one year to retain the health benefits and choose a brand in a dark bottle since light causes olive oil to deteriorate faster.

Bottom line: Extra-virgin olive oil offers many health benefits. However, it is important to recognize that not all olive oil is created equal.


Turmeric is a plant-based spice found in mustard and curry powder. Curcumin is the antioxidant (as well as the pigment) in turmeric that gives it a vibrant yellow color. Prior studies suggest turmeric may lower cholesterol and increase beneficial HDL cholesterol.

A more recent study involving post-menopausal women suggests turmeric may improve flow-mediated dilation of the heart and blood vessels. (In general, blood vessel performance worsens as we age, which is associated with cardiovascular-related disease.) Similarly, a 12-week study of men and post-menopausal women, randomized to receive curcumin supplementation or a placebo, showed that flow-mediated dilation improved in those receiving the curcumin supplement.

Bottom line: Even though more research is required for turmeric to be recommended as a dietary supplement or to firmly determine the antioxidant benefit of turmeric, this is still a good spice to add to your diet for flavor and color. In fact, below is a recipe that you could try.

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Turmeric is a good spice to add to your diet for color, flavor, and the antioxidant curcumin, which may lower cholesterol and increase beneficial HDL cholesterol.

Roasted turmeric cauliflower and broccoli

Makes: 8 servings


  • 1 medium head cauliflower
  • 1 medium bunch of broccoli
  • 4 or more cloves of garlic (optional)
  • 1 tablespoon olive oil
  • 1 tablespoon turmeric
  • ¼ teaspoon kosher salt
  • ¼ teaspoon black pepper


  1. Preheat oven to 350°F.
  2. Wash and cut cauliflower and broccoli to slightly larger than bite-size.
  3. Peel and press cloves of garlic.
  4. Toss vegetables and garlic in bowl with oil. Sprinkle with turmeric and salt, and toss well.
  5. Spread on cookie tray.
  6. Bake for 30 to 45 minutes (depending on how tender you prefer your vegetables), turning several times to brown all sides.

Nutrition facts per serving: Calories: 70, Total Fat: 2 g, Saturated Fat: 0.5 g, Sodium: 117 mg, Total Carbohydrate: 11 g, Dietary Fiber: 4 g, Sugar: 3 g, Protein: 4 g, Potassium: 573 mg.