Since the liver can achieve a plasma ketone body concentration of between 1-2mM24 when exposed to a high fat diet, what might be the advantage of an organ such as brain in possessing an endogenous ketogenic capacity? Firstly, it might provide a compensatory mechanism when, for reasons of reduced hepatic ketogenesis, plasma ketone body concentrations fall to lower limits (eg. 0.5 mM). This would hold true if there was an absolute requirement for a given concentration of ketone body within brain eg. 1 mM. However, there is some evidence to suggest that the brain as a whole uses ketone bodies facultatively, rather than having an obligate requirement for a minimum plasma concen-tration.25 Secondly, however, possessing an endogenous ketogenic capacity might expose ketolytic cell-types in the brain to ketone body concentrations that are simply unattainable in the plasma as a result of hepatic ketogenesis. This is potentially very important in the brain, since ketone body concentrations in the range of 2-5 mM cause significant perturbations in concentrations of key amino acid neurotransmitters.26,27 Such changes may have important consequences for the normal functioning of nerve cell discharge threshholds and, as a consequence of this, in the aetiology of epileptic seizure disorders.
Was this article helpful?
WHAT IT IS A three-phase plan that has been likened to the low-carbohydrate Atkins program because during the first two weeks, South Beach eliminates most carbs, including bread, pasta, potatoes, fruit and most dairy products. In PHASE 2, healthy carbs, including most fruits, whole grains and dairy products are gradually reintroduced, but processed carbs such as bagels, cookies, cornflakes, regular pasta and rice cakes remain on the list of foods to avoid or eat rarely.