Filtered coffee is the most common method of preparation in most places, notes a press release, but some people drink boiled coffee, in which coarse ground coffee is added directly to boiling water and left to brew. The reason for the difference in the effects on health? A molecule in coffee called diterpenes. Previous studies, the release notes, have shown that boiled coffee increases the risk of heart and vascular diseases, thanks to the presence of diterpenes, while filtered coffee doesn’t have these effects, and reduces the risk of type 2 diabetes.
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The release notes that other types of coffee preparation were not specifically investigated in the study, including instant, espresso, French press, and percolator coffee. Landberg stressed that preparation is not the sole determinant of health impact.