Consuming a cocoa product could help patients with kidney failure to improve their blood vessel function, according to research published in the Clinical Journal of the American Society of Nephrology.

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Cocoa flavanols may help the heart and the kidneys.

Individuals with failing kidneys have a higher risk of heart problems and are more likely to die from cardiovascular causes than from any other cause.

The heart and kidneys are major organs in the body; if either organ stops functioning properly, the other will be affected.

If the heart ceases to pump efficiently, it becomes congested with blood, pressure builds up, and there will be congestion of blood in the kidneys and a reduction in oxygenated blood there.

Conversely, damage to the kidneys can cause the hormone system that regulates blood pressure to go into overdrive in order to increase blood supply to the kidneys. As the heart then pumps against higher pressure in the arteries, it can be damaged by the extra workload.

Lifestyle and dietary modifications to maintain vascular health or reduce the risk could help protect heart health for those with kidney disease, but few therapeutic approaches of this sort currently exist.

What is so good about cocoa?

Cocoa flavanols have been shown to have beneficial effects on blood vessel function in individuals with normal kidney function.

The flavanols found in cocoa and dark chocolate are part of a larger group of compounds called flavonoids that occur naturally in plant foods, in this case, the cocoa bean. Flavanols are also found in red wine and tea, but those occurring in the cocoa bean are a unique mixture.

According to a report from Tufts University in Medford, MA, scientists have found that cocoa flavanols positively affect the circulatory system and help maintain the flexibility of arteries. The report states that in 2013, a European Union Commission approved a health claim that 200 mg of cocoa flavanols can "help maintain the elasticity of blood vessels, which contributes to normal blood flow."

This is equivalent to 2.5 g of high-flavanol cocoa powder or 10 g of high-flavanol dark chocolate. This cannot easily be compared with a bar of regular chocolate or other edible product, as the concentration of flavanol will depend on the processing and inclusion of other ingredients.

Cocoa improved circulation in kidney patients

Dr. Tienush Rassaf, of University Hospital Essen in Germany, and colleagues wanted to test the benefits of cocoa flavanols on patients with kidney problems.

A group of 57 patients who were undergoing dialysis were given either a test beverage rich in cocoa flavanols (900 mg per day) or a control beverage without cocoa flavanols - but with the same nutritional content as the test drink in all other aspects.

After 30 days, the investigators found that cocoa flavanol was well-tolerated by patients, and that it improved blood vessel function and reduced diastolic blood pressure. These effects were not observed in the group that consumed the control beverage.

Dr. Rassaf says:

"Impressively, the degree of reversion of vessel dysfunction was comparable to the effects observed through administering statins or making dietary and lifestyle changes. Whether this approach also leads to a reduction in mortality is not clear and has to be investigated."

In an accompanying editorial, Dr. Carmine Zoccali and Dr. Francesca Mallamaci, of the National Research Council Institute of Clinical Physiology (CNR-IFC) in Italy, noted that "the burden of cardiovascular disease in dialysis patients is so devastating that a promising intervention like cocoa flavanols deserves full attention by the nephrology community."

They add that if further studies confirm the findings, they could mark a fundamental change in patient care.

Medical News Today has previously reported on the possibility that cocoa flavanols can help improve memory function. This article also points out, however, that flavanols are often lost in processing, and to consume 900 mg a day, a special preparation would be needed.