BLOOD CHOLESTEROL

The effects of drinking different types of coffee on blood lipid levels including total, low density lipoprotein (LDL) and high density lipoprotein (HDL) cholesterol have been reviewed (1). The authors summarised the evidence that the diterpenes cafestol and kahweol are the cholesterol-raising factors in coffee and classified coffee brews as containing low, moderate or high levels of diterpenes.

Filtered coffee and instant coffee contain low levels of diterpenes. In some intervention trials, neither filtered coffee (2) nor instant coffee (3) had any effect on blood lipid levels. In one intervention trial, however, filtered coffee elevated both LDL- and HDL-cholesterol levels so that the ratio of LDL to HDL and hence the risk of cardiovascular disease did not change (4). Mocha coffee, common in Italy and Spain, and Espresso coffee contain moderate levels of diterpenes. Intervention trials have demonstrated that neither Mocha coffee (5) nor Espresso coffee (6) had any effect on total, LDL or HDL cholesterol levels. Boiled coffee and cafetiere coffee contain high levels of diterpenes. Intervention trials have demonstrated that both boiled coffee (2) and cafetiere coffee (7) raise total and LDL-cholesterol levels. However, the second of these studies has been criticised (8, 9) because the effect was small and within the normal diurnal and seasonal variation in cholesterol levels, the effect was of marginal statistical significance and there was evidence at the end of the 24-week study that cholesterol levels were falling again implying adaptation to coffee intake.

The caffeine content of coffee does not appear to have any influence on blood lipid levels. An intervention trial has shown that consumption of decaffeinated coffee did not lower total or LDL-cholesterol levels (10) and a cross-sectional study was unable to show any association between caffeine intake and total, LDL- or HDL-cholesterol (11). 

A meta-analysis of intervention trials published prior to December 1998 on the effects of coffee on blood lipid levels was published in 2001 (12). The authors identified twenty- three papers but excluded nine from their analysis due to design faults. A significant dose response relationship between consumption of all types of coffee and total or LDL cholesterol levels was shown. They observed greater effects in subjects with hyperlipidaemia or when either caffeinated and decaffeinated coffee or boiled and filtered coffee were compared.   

It can be concluded that heavy consumption of boiled coffee but not filtered coffee elevates blood total and LDL cholesterol levels. This effect is more obvious in hyperlipidaemic subjects. However, the clinical, statistical and long-term significance of the effects of boiled coffee on blood lipid levels has been questioned.  Although more common in Scandinavia and the Middle East, drinking boiled coffee is comparatively rare in most countries.
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