Although conventional biomedical research has largely focused on mechanisms of weight loss and genetic aspects of obesity, most medical solutions are plagued by side-effects and fraught with complex questions. As a consequence, consumers are seriously considering herbal products, nutraceuticals and functional foods as alternatives to conventional medications. This is evidently driven by a growing consumer understanding of diet/disease links, aging-related consequences, rising health care costs, and advances in food technology and nutrition. This study investigated the effects of up to 12 months exposure to a multinutrient and botanical extract supplement (Metabolic Nutrition System Orange (MNSO) - sold by AdvoCare, Carrollton, TX, USA) at five dietary concentrations on serum biochemistry and target organ histopathology of the hearts of B6C3F1 mice. The MNSO is a unique combination of vitamins, minerals, omega-3 fatty acids and herbal extracts designed to provide a strong foundation of nutritional support, and to enhance thermogenesis and perception of energy. The MNSO contain extracts of citrus, ephedra, guarana, gingko, green tea and Ocimum. In this study, female B6C3F1 mice were fed control (-MNSO) or MNSO (one time to ten times, one time = daily human dose) diets. Animals were sacrificed after 4, 8 and 12 months', at which time blood was collected for serum chemistry analysis, and hearts were prepared for histopathology and tissue biochemistry. Food consumption and body weight changes were also monitored throughout the study. The MNSO exposure did not significantly affect any of the cardiosensitive enzymes [including creatine kinase (CK), lactate dehydrogenase (LDH) and aspartate aminotransferase (AST)] and normal histopathological architecture of the heart was observed. Although animals given the MNSO diet consumed more food, they were relatively leaner and more active compared to controls. The results indicate that ingestion of ephedra and caffeine for one year in the doses used as part of a comprehensive metabolic nutrition system does not significantly alter normal serum chemistry or induce any irreversible histological changes in the mouse heart, since this study employed up to ten times the normal human consumption dose of ephedra and the metabolic nutrition system.