Many people rely on a hot cup of caffeine to help them get through the early morning. But before you go to the coffee pot for that second cup, read about this report.
Heavy consumption of unfiltered coffee may increase the risk of heart disease and stroke by up to 10 percent, Dutch researchers report.
According to their study, published in the American Journal of Clinical Nutrition, unfiltered coffee may raise blood levels of a compound called homocysteine.
High levels of homocysteine in turn appear to raise blood cholesterol levels, thereby increasing the risk of heart disease and stroke.
However, it is not clear if the elevate homocysteine was caused by diterpenes, chemicals found in coffee that are known to raise cholesterol and are removed by filtering, or by other factors that may also be found in filtered java.
The team of researchers randomly assigned 64 volunteers with normal homocysteine levels to one of two groups.
In one group, 30 people consumed six large cups (1 liter in total) of unfiltered coffee a day for two weeks.
The study participants prepared the coffee using a cafetiere coffeepot, which uses a plunger to separate the brew from the coffee grounds.
The second group included 34 people who drank unspecified amounts of water, milk, broth, tea and chocolate drinks instead of coffee.
After eight weeks, subjects were asked to switch to the regimen of the other group, so that both drank unfiltered coffee for two weeks. Blood tests were then taken to measure homocysteine and cholesterol levels.
The results showed that drinking large amounts of unfiltered coffee led to a 10 percent increase in homocysteine, which could translate into a 10 percent increase in the risk of heart disease.
"The observed effect of unfiltered coffee on plasma homocysteine in the present study suggests that individuals at risk of cardiovascular diseases should not drink large amounts of unfiltered coffee," wrote Dr. Marina J. Grubben and colleagues from the Agricultural University Wageningen in the Netherlands.
Further, the effect of filtered coffee on homocysteine levels also remains unclear, they noted.
The researchers said that most people drink less than six large cups of strong coffee per day used in the study.
Also, the researchers mentioned that it has not yet been shown that reducing high blood homocysteine levels cuts heart risk, but studies underway "may answer this question."