Metabolism is a key process to the function and survival of all living organisms. The role of metabolism is key in many pathologies, and presents a prime opportunity to both understand and treat disease in new ways. In particular, lactate is a molecule which has been known and studied for many years by a broad spectrum of scientists from many research fields, with it appearing to have a number of roles in the routine operation and function of living organisms, as well as signaling pathological disturbance of normal physiology in many circumstances. This thesis aims to further the understanding of how measuring and quantifying both lactate and sodium with both NMR and spectral photometric techniques can be a powerful tool for the researcher in cell, pre-clinical, and clinical research. The research for my PhD has focused on basic biology, pre-clinical large animal imaging, clinical sodium imaging in Multiple Sclerosis, and a physiological first in man study of the healthy brain with hyperpolarised [1-13C] pyruvate.