To drip or not to drip--that is the question--the type of coffee consumed in Sydney.

To the Editor: Coffee is enjoyed by many worldwide and its health impacts have been the subject of considerable scientific and public interest. One particular controversy relates to whether coffee increases the risk of developing coronary heart disease (CHD) (1) since CHD continues to be the single most common cause of death in industrialised countries including Australia (2).

It has been reported that some types of coffee brews raise serum cholesterol (3) and randomised controlled trials have confirmed that boiled coffee, but not filtered coffee, raises cholesterol levels (4). The observed rise in cholesterol has been found to be due to an increase in serum low-density lipoprotein cholesterol (LDL-C) (5). It was suggested that the alteration in lipid profile may have led to the development of CHD. The use of a paper filter effectively removes most of the cholesterol-raising factor (6). This may explain why Turkish/Greek, cafetiere, mocha and espresso coffee, have been found to raise serum cholesterol but not instant and percolated coffee (7). The diterpenes, cafestol and kahweol are the substances in coffee responsible (8) and boiled, Turkish/Greek and cafetiere coffee contain the highest levels of diterpene. Mocha and espresso coffee have moderate amounts. Percolated, instant and drip filtered coffee have low or negligible levels of diterpenes.

Coffee consumption in Australia is increasing (9). We set out to investigate the types of coffee beverages available and consumed across a range of cafes and specialised coffee shops in Sydney. The assessment of consumer awareness of the hypercholesterolaemic effect of some coffee was also undertaken. Two questionnaires were developed and piloted for this study. Due to limited resources and time constraints, the investigation was conducted within the Sydney central business district (CBD).

We found that espresso-based coffee beverages were widely available in cafes and specialised coffee shops across the Sydney CBD. It was also the preferred type of coffee for Sydney CBD coffee drinkers. Although drip filtered, percolated and instant coffee may be preferable coffee brews because they do not significantly affect serum cholesterol levels, many individuals surveyed, however, were not aware of the hypercholesterolaemic effect of certain types of coffee brews.

Espresso is a brewing method and is extracted under high pressure whereby water is forced through a bed of finely ground coffee beans (10). A randomised controlled trial found that consuming moderate amounts of espresso-based coffee does not significantly raise serum cholesterol in healthy people (11). However, in a meta-analysis of randomised controlled trials, the cholesterol-raising effect of coffee consumption was found to be more pronounced in individuals with hypercholesterolaemia (12). Thus, individuals with elevated cholesterol levels who drink a lot of coffee should consider selecting brews that are low in diterpene content.

A related statement can be found in a National Heart Foundation of Australia consumer publication recommending moderation in coffee consumed per day and providing a warning that boiling ground coffee beans may increase cholesterol levels (13).

References

1. Paul O, Lepper MH, Phelan WH, Dupertuis GW, Macmillan A, McKean H, et al. A longitudinal study of coronary heart disease. Circulation 1963;28:20-31.

2. Australian Institute of Health and Welfare, National Heart Foundation of Australia, National Stroke Foundation of Australia. Heart, stroke and vascular diseases [online]. 2001. Available from: URL: http://www.aihw.gov.au/publications/cvd/hsvd01/hsvd01.pdf. Accessed 10 August 2003.

3. Pietinen P, Aro A, Tuomilehto J, Uusitalo U, Korhonen H. Consumption of boiled coffee is correlated with serum cholesterol in Finland. Int J Epidemiol 1990;19:586-90.

4. Bak AA, Grobbee DE. The effect on serum cholesterol levels of coffee brewed by filtering or boiling. New Eng J Med 1989;321:1432-7.

5. Aro A, Tuomilehto J, Kostiainen E, Uusitalo U, Pietinen P. Boiled coffee increases serum low density lipoprotein concentration. Metabolism 1987;36:1027-30.

6. Ahola I, Jauhiainen M, Aro A. The hypercholesterolaemic factor in boiled coffee is retained by a paper filter. J Intern Med 1991;230:293-7.

7. Urgert R, Van Der Weg G, Kosmeijer-Schuil Truus G, Van De Bovenkamp P, Hovenier R, Katan Martijn B. Levels of the cholesterolelevating diterpenes cafestol and kahweol in various coffee brews. J Agri Food Chem 1995;43:2167-72.

8. Heckers H, Gobel U, Kleppel U. End of the coffee mystery; diterpene alcohols raise serum low-density lipoprotein cholesterol and triglyceride levels. J Intern Med 1994;235:192-3.

9. Department of Agriculture, Fisheries and Forestry Australia. Australian Food Statistics [online]. 2003. Available from: URL: http://www.affa.gov.au/corporate_docs/publications/pdf/food/austfoodsstats2003.pdf Accessed 2 September 2003.

10. Pictet G. Home and catering brewing of coffee. In: Clarker R, MacRae R, editors. Coffee. Vol 2. London: Elsevier Applied Science; 1987, p. 35-57.

11. D'Amicis A. Scaccini C, Tomassi G, Anaclerio M. Stornelli R, Bernini A. Italian style brewed coffee: effect on serum cholesterol in young men. Int J Epidemiol 1996;25:513-20.

12. Jee SH, He J, Appel LJ, Whelton PK, Suh I, Klag MJ. Coffee consumption and serum lipids: a meta-analysis of randomized controlled clinical trials. Am J Epidemiol 2001;153:353-62.

13. National Heart Foundation of Australia. Healthy eating for the heart: a guide to lowering your blood cholesterol. Sydney: National Heart Foundation of Australia; 2002.

S.E.J. Wong, D. Volker, S. Radd

Human Nutrition Unit, Department of Biochemistry.

The University of Sydney