Nutritional and racial determinants of the increase in plasma homocysteine levels after methionine loading
Current Therapeutic Research
Low circulating plasma levels of total homocysteine (tHcy) are associated with a lower prevalence of coronary heart disease among black people than among white people living in Burkina Faso. Objective: The purpose of this study was to provide a rationale for a possible mechanism for the decrease in plasma tHcy levels among black people compared with white people living in Burkina Faso. Methods: Healthy, black, adult, lifelong inhabitants of Burkina Faso and healthy, white adults born in Italy
... lts born in Italy but living in Burkina Faso 25 years were eligible for enrollment. Controlled diets were assigned to all subjects for 2 weeks before the study. After an overnight (1Zhour) fast, a methionineloading test was performed in all subjects. Plasma levels of tHcy, cysteine, glutathione, and cysteinylglycine were measured simultaneously using highperformance liquid chromatography after fasting (baseline) and at either 4 and 8 hours (n = 30) or 2, 4, 6, and 8 hours (n = 4) after methionine loading. During the 12 hours after loading, the clinical conditions and adverse events of subjects were monitored. Results were analyzed using the Student t test and Mann-Whitney U test. Results: Seventeen black adults (9 males, 8 females; median age, 21 years) and 17 white adults (8 males, 9 females; median age, 35 years) were enrolled. Mean plasma levels of tHcy, cysteine, and glutathione increased from mean baseline levels more slowly in the black group than in the white group and peaked 8 hours after methionine loading (16.