Coffee Study (2002)

Our aim was to investigate the bioavailability of coffee phenols and the effects of filtered coffee consumption on serum lipid peroxidation, the activity of antioxidant enzymes and plasma tHcy concentration.

Forty-five non-smoking voluntary men aged mean 26 years were recruited from the Kuopio area in eastern Finland through advertisement through e-mail and intranet of the University of Kuopio. Potential participants were screened in an interview for the following inclusion criteria: no severe obesity (BMI <32 kg/m2), no regular use of any drugs or supplement with antioxidative or lipid lowering properties, no chronic diseases like diabetes, CHD, claudication, cerebrovascular disease, hypothyreoidism or other major illness, willingness to abstain from coffee drinking or consume 3 or 6 cups of coffee for three weeks. From these subjects 35 men participated also short-terms study where they consumed 0, 1 or 2 cups of coffee. Volunteers were given freedom to participate to one or both of the studies. All criteria were ascertained prior to entering the study. A written informed consent was obtained from all participants. The study protocol was approved by the joint ethical committee for human research at the University of Kuopio and the Kuopio University Hospital.

Two-week wash-out period preceded the long-term study and during this period the use of coffee, tea, red wine, cocoa and chocolate were forbidden. Subjects were given caffeine tablets to be used if necessary to deal with withdraw symptoms. The maximum daily amount of caffeine was the amount comparable which would be obtained from the daily study bolus in the long-term study (0, 300 or 600 mg). After wash-out period subjects were free to choose whether they wanted to consume 0, 3 or 6 cups of coffee during the 3 wk clinical supplementation period. The study was not randomized to ensure compliance. Blood samples were drawn with Venoject vacuum tubes (Terumo) after overnight fast (10 hours).

Subjects collected 24-h urine excretion before study visits and were also advised to avoid the use of alcohol and analgesics three days and vigorous physical activity one day before the study visits. A four-day food recording was required before and during the last week of the intervention period to control for possible confounding factors and to check the compliance to given instructions. Food records were checked by a nutritionist together with the subjects and then analyzed by using the Nutrica software (version 2.5).  The coffee used in this study was normal filtered coffee packed in 500 g package. Subjects were instructed to measure the daily amount of coffee (teaspoon per one 1.5 dl cup) and to consume the daily amount in three portions.

The short term study was conducted directly after end-point measurements of long-term study. Subjects consumed 1/3 of the study bolus consumed in the long-term study (0, 1 or 2 cups), but otherwise continued to fast and blood sample was taken 1.5 hours after coffee ingestion. From the blood samples the following markers of lipid peroxidation were analyzed; formation of baseline conjugated dienes, hydroxy fatty acids and plasma F2-isoprostanes.

More information: jaakko.mursu at uef.fi

Our publications:

Jaakko Mursu, Sari Voutilainen, Tarja Nurmi, Georg Alfthan, Jyrki K Virtanen, Tiina H Rissanen, Pertti Happonen, Kristiina Nyyssönen, Jari Kaikkonen, Riitta Salonen, Jukka T. Salonen. The effect of coffee drinking on plasma total homocysteine concentration and oxidation of serum lipids, a clinical trial. Free Radicals in Biology and Medicine 2005;38:527-34.

Happonen P, Voutilainen S, Salonen JT. Coffee drinking is dose-dependently related to the risk of acute coronary events in middle-aged men. J Nutr 2004;134:2381-6.