|kefir with yacon, a prebiotic|
First thing to mention is that while glucose is an oxidative fuel for our bodies and brains, it is actually used to make ATP or adenosine triphosphate which is a usable form of energy for cells - "the energy is "trapped" in a chemical bond that can be released and used to drive other reactions that require energy. (endergonic reactions)." http://scienceline.ucsb.edu/getkey.php?key=2254
So how do we go from glucose to ATP? "This is achieved through the process of "oxidation" - and this is carried out through a series of metabolic pathways. Complex chemical transformations in the cell occur in a series of separate reactions to form each pathway, and each reaction is catalyzed by a specific enzyme. Interestingly, metabolic pathways are similar in all organisms, from bacteria to humans. In eukaryotes (plants and animals) many of the metabolic pathways are compartmentalized, with certain reactions occurring in specific organelles. Basically, cells trap free energy released from the breakdown (metabolism) of glucose. This energy gets trapped in the ATP as it converts from ADP to ATP by the addition of phosphate.
There are 3 main pathways for harvesting energy from glucose:
Glycolysis - begins glucose metabolism in all cells to produce 2 molecules of pyruvate. Occurs outside of mitochondria, usually in cytoplasm.
Cellular Respiration - uses oxygen from the environment and converts each pyruvate to three molecules of carbon dioxide while trapping the energy released in this process in ATP. There are 3 sub-pathways of cellular respiration - pyruvate oxidation, the citric acid (Krebs or Tricarboxylic Acid) cycle and the electron transport chain. Occurs in different sub-compartments of mitochondria.
Fermentation - converts pyruvate into lactic acid or ethanol; does not need oxygen. It is not as efficient as cellular respiration; it occurs in the cytoplasm." http://scienceline.ucsb.edu/getkey.php?key=2254
We want to look more into this but on first sight it seems we have an explanation, we are using the help of friendly micro-organisms to convert the sugars on milk or vegetables or honey into ATP, an immediate energy source for the body and brain.
Now the brain uses a lot of energy, a high percentage of the body's energy requirements. Glucose is a very immediate source of oxidative fuel for ATP production (and it seems the brain does need at least some glucose) while the breaking down of fat, protein of glycogen is a bit more long-winded. However it seems to us that fermented foods can supply instant brain energy without having to take in a lot of fruit sugar which, as many of us know can cause challenges to our bodies in other ways.
Could it be that in order to advance our evolution as a species we do need a more instantly accessible source of large amounts of energy for the brain and that by engaging harmoniously with friendly micro-organisms we have this?