 Cognitive tasks of differing levels of difficulty will be utilised with the hypothesis that energy expenditure parameters and blood flowoxygen extraction will increase with rising task demands, and that any treatment related effect will be more evident under conditions of increased neural activity. The effects on the above mentioned parameters of two multivitaminmultimineral preparations MMP will be compared to placebo subsequent to single dose administration acute and following daily administration over an eight week period chronic. The nutritional interventions are expected to improve nutritional status and thereby facilitate energy supply and metabolism and to have positive impact on the study parameters. The effects of the nutritional interventions on nutritional status will be evaluated by measuring the plasmaserum concentrations of a selected subset of analytes. It is hypothesized that the nutritional status at baseline and after eight week supplementation period will have an impact on metabolic substrate conversion, oxygen utilisation, cerebral blood flow and cognitive performance. 