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Issue 174 Item 13 Beneficial Effect of Dark Chocolate in Older Hypertensive Pati

Jun 22, 2004

Eating dark not milk chocolate for 2 weeks produced a fall in blood pressure.

Researchers from the University of Cologne, Germany, report in the August 27 issue of JAMA that eating dark chocolate for 2 weeks produced a fall in blood pressure in 13 otherwise healthy individuals with untreated hypertension.] The 6 men and 7 women aged 55-64 years, with recently diagnosed and untreated stage 1 mild isolated systolic hypertension, were randomly assigned to receive consecutive daily doses of either 100 mg dark chocolate containing 500 mg polyphenols and 480 kcal energy, or 90 mg white chocolate, also containing 480 kcal and similar nutrients but no polyphenols. After 14 days, the participants abstained from chocolate for 7 days, then switched groups. The chocolate bars were substituted for foods of similar energy and macronutrient composition.

Within 10 days of starting the dark chocolate, participants showed significant reductions in both SBP and DBP. At the end of the 14-day interventions, SBP had declined significantly by a mean of 5.1 mm Hg (P < .001) and DBP by 1.8 mm Hg (P < .002) in patients who consumed dark chocolate compared with those receiving white chocolate. Blood pressure levels returned to preintervention levels within 2 days of the end of each 14-day period. There was no effect of either type of chocolate on heart rate and there were no differences in effects between men and women.

Researcher Dirk Taubert, MD, PhD, and colleagues suggest that the plant polyphenols that are major constituents of cocoa solids in the dark chocolate have significant bioavailability and are responsible for the reductions in blood pressure seen in the study.

Nutritionists traditionally react with alarm to news that confers healthy properties on chocolate, and this study is no exception, with several commentators pointing to the high number of calories and fat contained in chocolate and people’s tendency to eat large amounts of it at any one time. However, several concede that if you must have a chocolate treat, “the bitterer the better!”

Various cardiovascular benefits reported for chocolate, especially dark chocolate, have been attributed to antioxidant properties of the polyphenol flavonoids it contains. A recent paper in Nature confirmed that plain, dark chocolate resulted in an increase in plasma antioxidant capacity in humans, but the joint Italian and UK group found that the effect was markedly reduced when the dark chocolate was consumed with milk or milk chocolate. “I guess this means to be healthy you should eat chocolate with red wine,” quipped Andrew L Waterhouse, PhD (University of California at Davis), adding, “That is, if you believe in the antioxidant hypothesis.” Dr Waterhouse, a chemist, has been at the forefront of research into the antioxidant properties of wine and chocolate.


FACT: Penicillin has been Associated With Reduced Risk of Stroke in Elderly Hypertensive Patients. A Canadian study in elderly hypertensive patients has found that those taking penicillin were about half as likely to have a stroke compared with those not taking penicillin. Paul Brassard (McGill University Health Centre, Montreal) and colleagues reported their study in Stroke.[4] Using the Quebec healthcare insurance database, they analyzed the records of 29,937 patients (average age 78 years) who were treated for hypertension between 1982 and 1995.