A trial duration of 3—4 weeks has previously been shown to be sufficient to get an effect of coffee on serum cholesterol Grubben et al, ; Christensen et al, The participants were recruited by advertisement in the largest newspaper in Gothenburg.
The coffee was provided to guarantee that they were all exposed to the same brand and quality of filter brewed coffee. All participants also got the same kind of standardised coffee filter and measuring spoon. Divergence from the four cups was reported. The participants were allowed to drink tea and other caffeine-containing beverages during the coffee-free periods.
Nonfasting blood samples were drawn at inclusion and at 3, 7, 10 and 14 weeks after start of the study. The blood samples were analysed for blood lipids total cholesterol, HDL cholesterol, triglycerides, lipoprotein a Lp a and urate in serum. Serum cholesterol and triglycerides were determined by an enzymatic procedure on a Hitachi analyzer. Serum urate was analysed by Hitachi autoanalyser.
Blood pressure was recorded by manual device, and EKG and heart rate were recorded at all five visits. The dietary habits were assessed by dietary frequency questionnaires at the beginning of the study. A follow-up survey with special emphasis on changes in food habits during the four different periods was undertaken. The dietary questionnaire was based upon a Norwegian version, which has been used in a number of previous studies Nes et al, The statistical significance of the differences was assessed by Student's t -test except for Lp a.
For this variable, signed rank test was used. Analysis of variance was performed to test whether the differences of the effect variables differed between the two trial periods. A total of people responded to the advertisement and of these fulfilled the criteria and were able to take part. Three people decided to withdraw during the study, leaving a total of participants.
One participant was not able to take part during the first period and five people were not able to take part in the last period, which resulted in participants in the first trial period and in the subsequent trial period. Serum total cholesterol decreased by 0. The decreases in HDL cholesterol were only 0. Serum triglycerides showed an inconsistent pattern with a significant decline during the first coffee abstention period, but a much smaller effect during the second abstention period.
Differences in heart rate were small and insignificant. Both systolic and diastolic blood pressure fell significantly during the first abstention period but the results were insignificant for the last abstention period. Total serum cholesterol increased during both trial periods by 0. There was also an incrementing effect on serum HDL cholesterol, serum triglycerides, serum urate, systolic blood pressure and heart rate in both periods, but the differences were significant only for serum urate in the first period The decline in total cholesterol during coffee abstention was significantly larger during the second trial period, whereas the cholesterol increase was larger during the first coffee exposure period.
The Lp a values were not normally distributed, and only median values and range are presented here. The average coffee intake prior to the study was 3.
Mean levels of BMI and age, and gender distribution, are shown in Table 3. The dietary survey showed that the intake of buns and cakes was unchanged in of the participants in the first coffee abstention period, and in of the participants for the second period Table 4.
For the coffee drinking period, the corresponding figures were of , and of , respectively. Intake of milk was unchanged in 97 of participants and 99 of for the two coffee abstention periods, and in of and of participants for the two coffee drinking periods.
Coffee consumption or noncompliance was reported by six people during the first coffee abstention period mean 1. A majority of the participants showed similar changes in blood lipids. In the two coffee abstention periods, 73 of and 83 of participants showed a decrease in serum cholesterol. Coffee drinking resulted in increasing serum cholesterol values in 81 of participants in the first period, and in 64 of the participants in the second coffee period.
The effect of abstaining from filtered coffee for 3 weeks resulted in a serum cholesterol decrease of about 0. These changes are unlikely a consequence of chance or confounding dietary factors such as changes in other food items corresponding to coffee intake. Coffee abstention may lead to either a reduction in milk consumption coffee with milk or an increase to compensate a decreased fluid intake.
The blood lipid changes in the present study were consistent with the results of Superko et al , Fried et al and Christensen et al In the study by Fried et al , total cholesterol increased by 0.
The differences were in both cases 0. Accroding to Aage Tverdal, a senior researcher at the Norwegian Institute of Public Health and lead author of the paper, he and his co-authors wanted to study the impact of different coffee brewing methods on heart health because it could be one of the many factors contributing to why some people who drink coffee see benefits and others do not. Since the s, scientists have understood that drinking coffee can impact cholesterol.
Research has shown that compounds called diterpenes in unfiltered coffee, specifically cafestol and kahweol two kinds of coffee oils , can raise LDL or bad cholesterol levels. The study focused specifically on drip coffee brewed with paper filters, the traditional preparation in Norway.
Another popular form of filtered coffee is the pour-over method. These results were not surprising to the researchers — or to Dr. If you drink coffee sporadically, meaning not every day, that can actually raise blood pressure. Registered dietitian Whitney Linsenmeyer, a spokesperson for the Academy of Nutrition and Dietetics and an assistant professor of nutrition at Saint Louis University , agrees that coffee can be part of a heart-healthy diet.
According to ISIC, other types of brewed coffee contain different levels of diterpenes and therefore have various effects on cholesterol levels:.
While the Food and Drug Administration FDA report that milligrams of caffeine per day is typically safe for health, caffeine may cause various clinically significant pharmacokinetic interactions with many drugs. A study found that coffee can interact with many drugs due to its caffeine content. A person may wish to consult their doctor to see whether any of their medications are in that category. In addition, the Centers for Disease Control and Prevention CDC warn against mixing a caffeinated beverage, such as coffee, with alcohol.
The combination may result in a person drinking more alcohol than they realize and thus experiencing more of its harmful effects. The amount of caffeine considered safe by the FDA is equivalent to four or five cups of coffee. However, some individuals are more sensitive to the effect of caffeine and may experience some of the following:. Other beverages containing caffeine include tea, sodas, and energy drinks.
Tea and sodas generally have less caffeine than coffee, while some energy drink brands may have two to three times the amount of caffeine in a coffee drink, according to the FDA. Although cafestol and kahweol can have a negative effect on cholesterol, they may also provide some health benefits. Research suggests they may have anti-inflammatory and anti-cancer properties. Cholesterol is a fat-like substance that promotes health when its levels in the body are healthy.
When cholesterol levels are too high , the fat builds up in the arteries. Once the fat accumulates enough to obstruct blood flow, it is dangerous, as it can cause a heart attack or stroke. Types of fats in the blood include :. While coffee does not contain cholesterol, it can affect cholesterol levels. Specifically, coffee diterpenes may cause an increase in total cholesterol and LDL levels.
Heart-healthy lifestyle changes may help lower cholesterol.
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