Chocolate for Blood Pressure Too Hard to Stomach, Researchers Say

August 13, 2010

August 13, 2010 (Adelaide, Australia) — A small Australian study looking at whether it would be practical to give people dark chocolate as a treatment to lower blood pressure long term surprisingly found that half of those who were assigned to the chocolate found it difficult to eat every day; they preferred to take a lycopene capsule [1].

Although many people may find these results difficult to digest, lead researcher Dr Karin Ried (University of Adelaide, Australia) told heartwire that it appears there is a difference between "consuming a food item voluntarily or having to eat it on a daily basis for 12 weeks." The participants in the study, who had to eat half a bar of dark chocolate a day, "reported strong taste and concerns about fat/sugar content as reasons for unacceptability of chocolate as a long-term treatment option," she said. Ried writes about her study, which was published last year, in a letter to BMJ August 10, 2010 [2].

Dr Brent M Egan (Medical University of South Carolina, Charleston), who recently wrote a review on the role of dark chocolate in the prevention and management of hypertension [3], told heartwire : "The Australian group has done a very nice study, and they have a history of doing high-quality research." However, there is another way of looking at this work, he said. "Fifty percent of the people said they were happy to eat the chocolate and liked it. And 73% said they would consume that amount of chocolate if it were known to have health benefits."

"If we have an intervention that's beneficial and that half the people would accept, that's pretty good, because clearly half of the people don't want to exercise vigorously and half certainly don't want to change their diet," Egan noted.

But Too Soon Yet to Advocate Chocolate as a Treatment for High BP

Egan is keen to stress, however, that it is far too soon to be recommending dark chocolate as a treatment for high blood pressure. "Clearly more research is needed; we don't think the state of the art is there yet. The number of studies is relatively small, few people have been studied, and the number of products that have been investigated is also too small to be making general health recommendations for the world."

Ried and her colleagues have also recently published a meta-analysis of 15 trials looking at this subject [4], and she says they too concluded that the studies "are too diverse to give confident answers on optimal dosage or duration of treatment." Their main finding, she says, "was that chocolate may help people with high blood pressure but not with normal blood pressure"--they found BP reductions of around 5 mm Hg systolic, which, "albeit modest, is comparable to the effects of 30 daily minutes of moderate exercise," she says.

But hypertension expert Dr Bryan Williams (University of Leicester, UK), who also discussed the study with heartwire , says he doesn't "ever see chocolate becoming a mainstream treatment for high blood pressure, although the observations are of interest.

"There is some reasonable science suggesting that there might be a modest effect [of chocolate on BP], but the whole issue is plagued by the possibility of publication bias," Williams adds. "Obviously, journals are excited about positive studies with chocolate because they know very well it's likely to be well read and well cited, but if you sent a paper in saying, 'We've just done a mega-study showing that chocolate does nothing for BP,' it's probably not going to be as exciting."

Another problem, says Williams, "is that any modest reduction in blood pressure--even if we give it the benefit of the doubt and say there is one--is likely to be offset by an increase in weight gain."

Brands May Vary in Their BP Lowering Effects

Egan says the recent literature review he and his colleagues performed did show that one brand of dark chocolate, consisting of 50% cocoa (Ritter Sport dark chocolate), has consistently lowered blood pressure in four studies, "while another manufacturer's chocolate (Mars Dove chocolate) has never lowered BP," he notes, so "we think it makes a difference which dark chocolate is selected and how the cocoa beans are processed.

"If BP is altered differentially by various brands of dark chocolate, this information could facilitate efforts to identify the source of those differences, maximize the BP benefits of cocoa/dark chocolate, and produce nutraceuticals that lower BP," he and his colleagues conclude.

Ried et al declare no competing interests. Egan reports no disclosures.


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