From Scientific American:
The Dutch have a long history with chocolate. Although native Mexicans and their Spanish conquerors first used the bitter bean–and reported on its tonic powers–a Dutchman was the first to extract modern cocoa and neutralize its bitterness with alkali. The modern chocolate bar was born. Now, results from a study of aging Dutch men have shown that cocoa consumers were half as likely to die from disease than those who did not eat the sweet treat.
Brian Bujisse of the National Institute for Public Health and the Environment in Bilthoven and his colleagues measured the cocoa intake of 470 men between 1985 and 2000 as part of the Zutphen Elderly Study, a longitudinal look at nearly 1,000 Dutch men between 65 and 84 years of age. Among those who ate the most chocolate–averaging more than four grams a day–average systolic and diastolic blood pressure was 3.7 and 2.1 millimeters of mercury lower than their chocolate-spurning peers. This result did not hold true for other sweet foods nor did it vary among men who also smoked, were inactive or consumed a lot of alcohol. And, despite being strongly associated with greater intake of calories, chocolate lowered the overall risk of cardiovascular or any other disease by as much as 50 percent.