Statin therapy depresses fat metabolism in older individuals

Objective: Statins (3-hydroxy-3-methylglutaryl coenzyme A [HMG CoA] reductase inhibitors) reduce blood lipoproteins and reduce the risk of cardiovascular events. However, they may reduce fat metabolism. This study tested the hypothesis that total body fat oxidation is reduced by statins in older subjects and the reduction is not due to substrate availability. Methods: A total of 14 elderly patients (71 ± 6 years) on statin therapy were compared with 14 matched elderly controls (75 ± 7 years). Subjects were tested for respiratory exchange ratio (RER) during both maximal and submaximal sustained (70% Vo_2max) exercise to voluntary exhaustion. Blood samples were drawn for lipoprotein analysis and substrate availability. Results: RER was significantly higher in subjects taking statins during both the max and submax tests, indicating reduced fat oxidation. Blood lipoprotein levels after a fast were not different between the statin and control groups. Levels of glucose, lactate, or triglyceride were not different between groups; however, free fatty acid levels were elevated by exercise in the statin group. Fat oxidation was significantly reduced in older subjects taking statin drugs that were not associated with diet, exercise, and fitness, which were matched between groups, nor availability of fat from the blood, which was higher in the statin group. Conclusion: Although statin therapy normalizes blood lipoproteins, it reduced fat metabolism in older individuals, which cannot be a result of lower availability from blood.