Unfiltered Coffee Raises Serum Cholesterol, Liver Enzymes
WESTPORT, Nov 29 (Reuters) - One study in tomorrow's issue of the British Medical Journal shows that cafetiere (brewed, unfiltered) coffee raises serum LDL cholesterol levels and serum concentrations of alanine aminotransferase. A second study shows that caffeine intake during pregnancy is linked to low-birth-weight infants.
Cafetiere coffee is made by pouring boiling water over ground coffee in a container with a sieve plunger. Dr. Rob Urgert and others at Wageningen Agricultural University in the Netherlands had 22 subjects drink five to six cups of the unfiltered cafetiere coffee a day for 24 weeks, while 24 subjects drank the same amount of filtered coffee. The amount of caffeine in each cup was identical for both groups.
Dr. Urgert observed that unfiltered coffee raised alanine aminotransferase 80% above baseline levels relative to filtered coffee. In fact, enzyme levels exceeded the upper limit of normal in 8 of the 22 subjects who drank unfiltered coffee. Cafetiere coffee drinking increased LDL cholesterol levels 9%-14%. Triglyceride levels rose initially in the study subjects, but returned to normal before the end of the study period. Once the subjects stopped drinking cafetiere coffee, the liver enzyme and LDL cholesterol concentrations returned to baseline levels.
The Dutch investigators write that "Daily consumption of five to six cups of strong cafetiere coffee affects the integrity of liver cells..." and they attribute the increases in cholesterol and alanine aminotransferase concentrations to the diterpenes cafestol and kahweol that are abundant in cafetiere. Dr. Urgert's team notes that both diterpenes are removed when coffee passes through paper filters, a process that does not take place when brewing cafetiere coffee.
"The effects on aminotransferases may be innocuous," they write, "but the effects on cholesterol concentration increase coronary risk and could be a reason to advise patients to drink filtered rather than cafetiere coffee."
In another study, London researchers led by Dr. Derek G. Cook of St. George's Hospital Medical School, examined the association between caffeine intake, plasma caffeine concentrations during pregnancy, and fetal growth and birth weight.
They found that while the women did not change their caffeine consumption during pregnancy, caffeine concentrations in their blood increased 75%. The researchers found no relationship between blood caffeine concentrations and fetal growth, but they report that caffeine intake was inversely related to birth weight; there was a "...1.3% fall in birth weight for a 1000 mg per week increase in intake."
Dr. Cook adds: "The apparent caffeine effect was confined to cigarette smokers..." and that "...the effect remains of borderline significance after adjustment for other factors." Dr. Cook says his study lends further support for the recommendation that women limit their caffeine intake and stop smoking during pregnancy.