A ketogenic diet is one that causes the body to breakdown or use ketones to produce energy to supply the body’s metabolic demands.
A ketogenic diet is one that contains a high in lipid content (fat), protein, and low in carbohydrates. It is primarily used in the treatment and mangement of childhood seizures that are very difficult to control via other means.
The ketogenic diet forces the human body to burn lipids derive energy. Ketogenesis is a much more energy intensvie process than obtaining energy in the from of glucose through the breakdown of carbohydrates in our diet.
Typically the body obtains the majority of its energy through carbohydrate digestion. Carbohydrates are brokendown to disaccharides then into monosaccharides (glucose).
Disaccharides (maltose, lactose, sucrose)
absorption accross the intestinal epitheliumof the jejumun and the ileum by facitilted diffusion or co-transport proteins
enter capillaries of the jejunum and ileum by facilitated diffusion
monosaccharides are then transproted to the liver via the hepatic portal vein for blood sugar regulation
A ketogenic diet is predominantly comprised of lipids such as oils, butter, and whipping cream. When the body’s only option to produce energy is through the breakdown of lipids, the resultant digestion process is known as ketosis. When fats are burned incompletely, ketones are produced. Fats are burned incompletely in the absence of sufficient glucose.
Bile salts:produced by the liver, stored and released by the gall bladder into the duodenum via the cystic duct, the common hepatic duct which becomes the common bile duct and the spincter of Oddi to emulsify fats.
H2O and HCO3 present in bile neutralize acidic chyme
lecithin present in bile salts forms micelles around lipids allowing them to be transported
Small lipid droplets (triglycerides)
Lingual lipase: from under the tongue, acts in the mouth
Pancreatic Lipase:produced and secreted by the pancrease into the duodenum.
Monoglycerides and Fatty Acids
enter into duodenal and jejunum epithelium
reformed into tryglycerides
wrapped in proteins for transport called chylomicrons
lipids enter lacteals by exocytosis
enter lymph vessels
transported to heartas lymph empties into the left internal jugular vein and the right subclavien vein
enter blood circulation
Lipid metabolism (energy production)
Lipids (triglycerides) are converted into glycerol and fatty acids through a process called lipolysis.
glycerol and fatty acids then enter into the kreb’s cycle to produce energy in the form of ATP
this energy is used by all cells in the body
fatty acids are converted into ketones by the liver, then enter the kreb’s cycle to make ATP
in ketosis, ketones are the predominant energy source for the body
Typically, our bodies derive the majority of its energy through carbohydrate metabolism and glucose is the predominant energy source.
The ketogenic diet
The “classic” ketogenic diet contains a 4:1 ratio by weight of fat to combined protein and carbohydrate.
This is achieved by eliminating foods high in carbohydrates (starchy fruits and vegetables, bread, pasta, grains and sugar) while increasing the consumption of foods high in fat (cream and butter).
Ketogenic diet and seizure control
- a ketogenic diet has been used for years to manage seizures where partial or complete symptom relief is not able to be acheived through antiepileptic medications.
- The biochemical basis of the dietary effect is unclear.
- The diet alters metabolism of amino acids in the brain
- one of these amino acids is glutamic acid, a major excitatory neurotransmitter
Research shows that:
1) the diet results in a decrease in the rate of glutamate transamination to aspartate that occurs due to reduced availability of oxaloacetate, the ketoacid precursor to aspartate
2) the ketosis process also increases conversion of glutamate to GABA, gamma aminobutyric acid: an amino acid that is found in the central nervous system; acts as an inhibitory neurotransmitter
3) increased uptake of neutral amino acids into the brain.
These three findings may suggest the method of ketosis on effectively controlling previously difficult-to-control seizures in the brain.
Martini, Fredric, H. 2006. Fundamentals of anatomy and physiology. 7th ed. Pearson Education Inc. USA.
Daikhin, Yevgeny, Lazarow, Adam, Nissim, Ilana, Nissim, Itzhak, and Yudkoff Marc. 2001. Ketogenic diet, amino acid metabolism, and seizure control. Journal of Neuroscience Research. 66 (5) : 931 – 940.