BACKGROUND: There have been no reports available about the direct effect of beer on serum enzyme activity.OBJECTIVE: To observe the changes of the activity of various serum enzymes of the subjects in the in vivo and in vitro experiments after drinking bear.DESIGN: An observational controlled experiment.SETTING: The Institute of Basic Medicine of Taishan Medical College.PARTICIPANTS: The experiment was performed at the Institute of Basic Medicine of Taishan Medical College between March 2005 and April 2005.We selected 17 college students, aged 19 to 35 years, from Taishan Medical College, including undergraduate students and graduate students. In formed consents were obtained from the subjects before the experiment was conducted.METHODS: ① In vivo experiment: 3 mL of venous blood was collected from the subjects 3 hours after the ordinary diet as the control. Then, the subjects drank beer at an amount of 4 mL/kg according to their body mass immediately. 3 mL of blood was collected respectively 15, 30, 45, 60, 90,120, 80 minutes later to measure the changes of the activity of alanine aminotransferase, aspartate aminotransferase, γ-glutamyl transpeptidase, al kaline phosphatase, creatine kinase , lactate dehydrogenase, diastase and lipase. ② In vitro experiment: 17 fresh serum samples were added into two test tubes separately with 0.5 mL of serum in each tube. 20 μL of normal saline was added to the tube of the control and 20 μL of beer was added into the test tube. The direct effect of beer on the activity of various enzymes was observed.MAIN OUTCOME MEASURES: The changes of the activity of alanine aminotransferase, aspartate aminotransferase, γ-glutamyl transpeptidase, al kaline phosphatase, creatine kinase , lactate dehydrogenase, diastase and lipase of the serum on the in vivo and in vitro experiment .RESULTS: Totally 17 students were involved and all the students entered the stage of result analysis with no loss in the midway. ① In vivo experiment: Beer significantly decreased the activity of serum aspartate aminotransferase (418.08 ±58.68,383.41 ±63.01)nkat/L, significantly in creased the activity of serum alkaline phosphatase, (367 8.57±436.25,396 2.96±400.91)nkat/L (x2=19.00-20.00,P ＜ 0.01). The activity of other enzymes was all increased at different degrees. ② In vitro experiment: Beer inhibited the activity of various enzymes in vitro to a certain degree.CONCLUSION: Beer has some effect on enzyme activity in vivo and in vitro, thus affecting the body metabolism. Over drinking beer can affect health. In the routine detection of serum enzymes, attention should be given to avoid the interference caused by over drinking beer to make sure the experimental results are precise and reliable.