Coffee and Chocolate for Heart Health

by Leigh on August 12, 2014

coffee chocolate heart health polyphenolsThere are probably few things more welcome than some evidence-based advice to include chocolate and coffee in your diet to support heart health, but this is precisely the recommendation that can be taken from a recent study presented at the European Atherosclerosis Society 2014 Congress (EAS 2014). The study looked at the influence of dietary polyphenols on glucose metabolism in people at high risk of diabetes and cardiovascular disease and determined that a diet that included coffee and chocolate as sources of polyphenols was realistic and relatively easy to maintain.

Of course, we should be quick to point out that this does not mean that heart health will benefit from an increased intake of sugar-laden milk chocolate, nor a daily regime of multiple cups of coffee with creamer and sugar. Instead, the study led to recommendations to include plant polyphenols from dark chocolate, green tea, olive oil and coffee.

How Polyphenols Help the Heart

Polyphenols are thought to help with cardiovascular health by improving the function of insulin-producing beta-cells in the pancreas and supporting glucose metabolism. By assisting in the regulation of blood glucose these plant compounds can lower risk factors for diabetes, metabolic syndrome, and heart problems. They may even help reduce the risk of certain cancers by controlling levels of systemic inflammation and abnormal cellular changes connected to elevated blood sugar and insulin.

In this recent study the researchers randomised 45 patients who were assessed as being overweight or obese (body mass index >30) to consume one of four diets:

  1. A standard diet low in omega-3 fatty acids and polyphenols.
  2. A diet rich in omega-3 fatty acids.
  3. A diet rich in polyphenols.
  4. A diet that included both omega-3 fatty acids and polyphenols.

The participants ate like this for eight weeks, after which they were assessed for body weight, plasma glucose and insulin, beta-cell function, and glucose absorption. Those eating the omega-3 rich diet lost more weight over the study but those eating the diet rich in polyphenols had greater improvements in plasma glucose and insulin when assessed using an oral glucose tolerance test.

Improvements in glucose metabolism were only seen in the people on the polyphenol-rich diet, which included more polyphenols than the diet rich in both omega-3 and polyphenols. Pancreatic beta-cell function and glucose absorption improved in the polyphenol group, suggesting that this type of diet could be helpful in preventing metabolic diseases like diabetes.

Olive Oil and Grape Seed for Heart Health

Another study, also presented at the conference, reported on the benefits for heart health or olive and grape seed extracts. Olive oil, as noted above, contains polyphenols, while grape seed is a source of catechins and proanthocyanidins, two compounds seen in other studies to be linked to better cardiovascular function. This latest study tested the combined extract on 72 healthy men and women and assessed vascular function after four weeks.

What the researchers found was that those receiving the extract had increased flow-mediated dilaton (0.52%) compared to a decrease in FMD (0.9%) in the control group. Catechins and proanthocyanidins exert antioxidant effects as well as antihypertensive, and anti-inflammatory effects and were seen in this study to help reduce levels of C-reactive protein, a marker for inflammation.

Mediterranean Diet for Healthy Hearts

Olive oil, coffee, grape seed, dark chocolate and other foods rich in polyphenols are typical of a Mediterranean-style diet and are thought to be part of the reason why such a diet has been seen to benefit heart health.

These studies certainly do not suggest that heart health will be benefited simply by adding chocolate and coffee, or grape seed and olive oil to the diet while continuing to consume saturated fats (especially animal fats), sugar and simple carbohydrates. A heart-healthy diet would likely include rich sources of polyphenols, proanthocyanidins and catechins from healthy whole grains, plant proteins, fresh fruits and vegetables, nuts and seeds.


Bozzetto L. Diets naturally-rich in polyphenols improve glucose metabolism in people at high cardiovascular risk: A controlled randomized trial. EAS 2014; June 1, 2014; Madrid, Spain. Abstract M087.

Kominami M. Supplementation of olive and grape seed extracts improves vascular function in healthy humans: a randomized controlled study. EAS 2014; June 1, 2014; Madrid, Spain. Abstract M090.

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