Chocolate treats diabetes…. but only without sugar and milk.

Cocoa flavanols show promise for diabetic cardiovascular health

by Jess Halliday

27-May-2008 – A new study has indicated that cocoa flavanols could help improve blood vessel health in diabetes patients, potentially offering protection against cardiovascular complications that standard medication does not.

People who suffer from type 2 diabetes are known to have impaired blood vessel function, which puts them at higher risk of cardiovascular disease. Indeed, even when medical treatment such as insulin addresses the main symptoms of diabetes, as many of two thirds of sufferers are said to eventually expire as a result of cardiovascular disease and stroke.

The researchers of the new study, published in the Journal of the American College of Cardiology, noted that “the overall prognosis is unfavourable due to deteriorated cardiovascular risk”.

This has caused diabetes experts to cast about for new approaches and lifestyle changes that could help reduce the risk of diabetes complications.

The team, from Germany and the US, was aware of epidemiological data that diets rich in flavanols are associated with a reduced cardiovascular risk. They set out to test the feasibility and efficacy of a dietary intervention based on daily intake of a flavanol-containing cocoa beverage on vascular function in diabetes sufferers.

The intervention made use of a beverage prepared by the Cocoapro process developed by confectionery firm Mars, which is designed to retain more of the flavanols in cocoa than typical processing methods.

The study was conducted in two parts. The first, a prospective study involving ten people with type 2 diabetes also taking medication, was intended to ascertain the immediate effects of the cocoa beverage on flow-mediated dilation (FMD), the measure of a blood vessel’s healthy ability to relax.

The beverages contained different flavanol levels – either 75mg, 371mg, or 963 mg. The participants’ blood vessel function was measured in the hours following consumption, and a positive correlation was found between flavanol dose and immediate FMD improvements.

In the second part of the study 41 adults with type 2 diabetes, also currently taking medication, were divided into two groups. Members of one group were given a cocoa beverage containing 321 mg of flavanols three times a day, for 30 days.

Members of the second group received a control cocoa beverage containing just 25mg of cocoa flavanol. The two beverages had the same calories, nutrients and other cocoa compounds, such as caffeine and theobromide.

The researchers saw that the flavanols’ immediate effect on FMD was complemented by a sustained improvement over the 30 day period. Indeed, a 30 per cent increase in FMD was seen between day one and day 30.

Other measures, such as endothelium-independent responses, blood pressure, heart rate and glyaemic control were not affected by the intervention.

The findings have been met with enthusiasm by Mars. Chief scientific officer Harold Schmitz, PhD, said “the implications with regard to health and quality of life could be remarkable”.

Paul Zimmet, MD, PhD, director of the International Diabetes Institute in Australia, was also upbeat about the potential.

“While more research is needed, this study shows tremendous potential for future flavanol-based applications,” he said.

Indeed, the study researchers agreed over the need for more science in this area. They said larger trails are necessary for the full clinical relevance of flavanol-rich foods to be demonstrated, in the context of cardiovascular health and disease.


Journal of the American College of Cardiology 51:2141-2149
“Sustained benefits in vascular function through flavanol-containing cocoa in medicated diabetic patients: A double-masked, randomised, controlled trial”
Authors: Balzer J, Rassaf T, Heiss C, Kleinbongard P, Lauer T, Merx M, Heussen N, Gross HB, Keen CL, Schroeter H, Kelm M



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