"Thought there was no discussion of cost, most people have a general idea how much cocoa costs. The story fails to describe the improvement in blood flow in absolute terms, instead noting only relative or percent improvement (e.g. 37% compared to baseline for consumption of artificially sweetened cocoa). The reported 37% improvement is much greater than that reported in a press release from the American College of Cardiology (2.4% over baseline); the reason for the discrepancy is unclear. The story notes that chocolate is laden with fat and calories, potentially harmful in people who are already overweight or obese. This story is based on the preliminary results of a small, unpublished study presented at a national cardiology meeting. The researchers fed three different foods (two types of chocolate and a placebo whey powder) to 39 people during three separate 6-week trials, and then after each trial used ultrasound to measure arterial blood flow in the arms of their subjects, a test that purportedly “corresponds well to heart disease.” Unfortunately, the story says little about the methodological shortcomings inherent in such a research design. Are there enough subjects in the study to muster the statistical power to answer the question being asked—or could the improvements in blood flow be the result of chance? Did the researchers account for other factors that might affect arterial blood flow, such as exercise routines? Is there research to suggest that the observed differences in arterial blood flow correspond to any outcome of clinical significance, such as rates of heart attack, stroke, or death? This news report says nothing about such potential limitations. We suspect many observers would say that this study simply raises an interesting question, but certainly doesn’t answer it. Despite the researcher’s assertion–""This tells you that it (cocoa) is cardio-protective""–the data seem only to show that cocoa simply relaxes smooth muscle in the arm."
Study: Dark chocolate improves blood vessel health