Dark chocolate: Half a bar per week to keep at bay the risk of heart attack
An Italian study, the first outcome of a large epidemiological investigation, finds new beneficial effects of chocolate in the prevention of cardiovascular disease
6.7 grams of chocolate per day represent the ideal amount for a protective effect against inflammation and subsequent cardiovascular disease.
The findings, published in the last issue of the Journal of Nutrition, official journal of the American Society of Nutrition, come from one of the largest epidemiological studies ever conducted in Europe, the Moli-sani Project, which has enrolled 20,000 inhabitants of the Molise region so far. By studying the participants recruited, researchers focused on the complex mechanism of inflammation. It is known how a chronic inflammatory state represents a risk factor for the development of cardiovascular disease, from myocardial infarction to stroke, just to mention the major diseases. Keeping the inflammation process under control has become a major issue for prevention programs and C reactive protein turned out to be one of the most promising markers, detectable by a simple blood test.
"We started from the hypothesis- says Romina di Giuseppe, 33, lead author of the study- that high amounts of antioxidants contained in the cocoa seeds, in particular flavonoids and other kinds of poly-phenols, might have beneficial effects on the inflammatory state. Our results have been absolutely encouraging: people having moderate amounts of dark chocolate regularly have significantly lower levels of C-reactive protein in their blood. In other words, their inflammatory state is considerably reduced." The 17% average reduction observed may appear quite small, but it is enough to decrease the risk of cardiovascular disease for one third in women and one fourth in men. It is undoubtedly a remarkable outcome".
Chocolate amounts are critical. "We are talking of a moderate consumption. The best effect is obtained by consuming an average amount of 6.7 grams of chocolate per day, corresponding to a small square of chocolate twice or three times a week. Beyond these amounts the beneficial effect tends to disappear".
From a practical point of view, as the common chocolate bar is 100 grams, the study states that less than half a bar of dark chocolate consumed during the week may become a healthy habit. What about the milk chocolate? "Previous studies- the young investigator continues- have demonstrated that milk interferes with the absorption of polyphenols. That is why our study considered just the dark chocolate".
Researchers wanted to sweep all the doubts away. They took into account that chocolate lovers might consume other healthy food too, as wine, fruits and vegetables. Or they might exercise more than others people do. So the observed positive effect might be ascribed to other factors but not to cocoa itself. "In order to avoid this - researcher says - we "adjusted" for all possible "confounding" parameters. But the beneficial effect of chocolate still remained and we do believe it is real".
Resveratrol, red wine compound linked to health, also found in dark chocolate and cocoa.
The levels of resveratrol found in cocoa and chocolate products is second to red wine among known sources of resveratrol and forms yet another important link between the antioxidants found in cocoa and dark chocolate to other foods.
"Cocoa is a highly complex natural food which contains in excess of seven hundred naturally occurring compounds, with many more yet to be discovered," explains Jeff Hurst, the lead chemist on the project. "For years, flavanols, a different class of compounds in chocolate, received most of the attention, but these are quite different than resveratrol. It is exciting to see additional antioxidants identified in cocoa and chocolate."
The results of the survey show that cocoa powder, baking chocolate and dark chocolate contain on average 14.1 to 18.5 micrograms of resveratrol per serving while the level found in the average California red wine is 832 micrograms per glass. Roasted peanuts have an average of 1.5 micrograms and peanut butter, 13.6 micrograms of resveratrol per serving: demonstrating that cocoa and dark chocolates are meaningful sources of resveratrol in the US diet.
Consumption of small amounts of dark chocolate associated with reduction in blood pressure
Eating about 30 calories a day of dark chocolate was associated with a lowering of blood pressure, without weight gain or other adverse effect.
Previous research has indicated that consumption of high amounts of cocoa-containing foods can lower blood pressure (BP), believed to be due to the action of the cocoa polyphenols (a group of chemical substances found in plants, some of which, such as the flavanols, are believed to be beneficial to health). “A particular concern is that the potential BP reduction contributed by the flavanols could be offset by the high sugar, fat and calorie intake with the cocoa products,” the authors write. The effect of low cocoa intake on BP is unclear.
Dirk Taubert, M.D., Ph.D., of University Hospital of Cologne, Germany, and colleagues assessed the effects of low regular amounts of cocoa on BP. The trial, conducted between January 2005 and December 2006, included 44 adults (age 56 through 73 years; 24 women, 20 men) with untreated upper-range prehypertension (BP 130/85 – 139/89) or stage 1 hypertension (BP 140/90 – 160/100). Participants were randomly assigned to receive for 18 weeks either 6.3 g (30 calories) per day of dark chocolate containing 30 mg polyphenols or matching polyphenol-free white chocolate.
The researchers found that from baseline to 18 weeks, dark chocolate intake reduced average systolic BP by _2.9 (1.6) mm Hg and diastolic BP by _1.9 (1.0) mm Hg without changes in body weight, plasma levels of lipids or glucose. Hypertension prevalence declined from 86 percent to 68 percent. Systolic and diastolic BP remained unchanged throughout the treatment period among those in the white chocolate group.
“Although the magnitude of the BP reduction was small, the effects are clinically noteworthy. On a population basis, it has been estimated that a 3-mm Hg reduction in systolic BP would reduce the relative risk of stroke mortality by 8 percent, of coronary artery disease mortality by 5 percent, and of all-cause mortality by 4 percent,” the authors write.
“The most intriguing finding of this study is that small amounts of commercial cocoa confectionary convey a similar BP-lowering potential compared with comprehensive dietary modifications that have proven efficacy to reduce cardiovascular event rate. Whereas long-term adherence to complex behavioral changes is often low and requires continuous counseling, adoption of small amounts of flavanol-rich cocoa into the habitual diet is a dietary modification that is easy to adhere to and therefore may be a promising behavioral approach to lower blood pressure in individuals with above-optimal blood pressure. Future studies should evaluate the effects of dark chocolate in other populations and evaluate long-term outcomes,” the authors conclude.
Cocoa Health Benefits
Norman Hollenberg, professor of medicine at Harvard Medical School has spent years studying the benefits of cocoa drinking on the Kuna people in Panama. He found that the risk of 4 of the 5 most common killer diseases: stroke, heart failure, cancer and diabetes, is reduced to less then 10% in the Kuna. They can drink up to 40 cups of cocoa a week. Natural cocoa has high levels of epicatechin.
'If these observations predict the future, then we can say without blushing that they are among the most important observations in the history of medicine,' Hollenberg says. ‘We all agree that penicillin and anaesthesia are enormously important. But epicatechin could potentially get rid of 4 of the 5 most common diseases in the western world, how important does that make epicatechin?... I would say very important’
Nutrition expert Daniel Fabricant says that Hollenberg’s results, although observational, are so impressive that they may even warrant a rethink of how vitamins are defined. Epicatechin does not currently meet the criteria. Vitamins are defined as essential to the normal functioning, metabolism, regulation and growth of cells and deficiency is usually linked to disease. At the moment, the science does not support epicatechin having an essential role. But, Fabricant, who is vice president scientific affairs at the Natural Products Association, says: 'the link between high epicatechin consumption and a decreased risk of killer disease is so striking, it should be investigated further. It may be that these diseases are the result of epicatechin deficiency,' he says.
Epicatechin is also found in teas, wine, chocolate and some fruit and vegetables.