A new study from Norway has found that coffee drinkers who quit drinking caffeinated filtered coffee cut their blood levels of cholesterol and the protein homocysteine, which are known risk factors for heart disease. Previous research found a similar effect with boiled coffee, which is not filtered and therefore contains more of the naturally occurring organic compounds found in coffee grounds. Some of these compounds, called terpenoids, are known to increase cholesterol levels. However, the question of whether coffee increases heart disease risk has been controversial, with some, but not all, studies showing a link between coffee drinking and an increased risk. Lead author Dr. Benedicte Christensen of Ulleval University Hospital in Oslo, Norway, explained that "it is not only unfiltered coffee, but notably normal filtered coffee affects cholesterol and homocysteine." "If your cholesterol or homocysteine level is too high and you are a heavy coffee drinker you should consider reducing your consumption," he told Reuters Health. In the study, the researchers evaluated blood samples from 191 non-smoking coffee drinkers between the ages of 24 and 69. The otherwise healthy volunteers were randomly split into three groups. One group consumed no coffee, another drank between 1 and 3 cups of coffee per day and the third group drank more than 4 cups of coffee each day. The study period lasted for 6 weeks and each participant gave blood samples at the beginning of the study, after 3 weeks and at the end of the study period. All of the coffee drinkers used standard coffee brewing methods, including coffee filters, the authors note in the August 23rd issue of the American Journal of Clinical Nutrition. After 6 weeks, participants who abstained from consuming coffee showed a 10 per cent decrease in homocysteine levels. Quitting cut total cholesterol levels by 0.28 millimoles per litre, a weaker effect than seen in previous studies. The findings "indicate that the terpenoids that cause an elevated concentration of total cholesterol are only partly removed by a coffee filter," the researchers report. Christensen noted that while the aim of the current study was not to identify a biological explanation for the relationship between coffee and homocysteine levels, he speculates that coffee consumption may interfere with the body's ability to keep homocysteine levels in check, possibly by inhibiting the action of the vitamins folate or B6.