Difference between revisions of "Ketones"

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[[File:Ketones.png|right|thumb|500px|The three Ketones are interrelated. The body can convert between AcAc and BOHB, but AcAc spontaneously decomposes into Acetone.]]
 
[[File:Ketones.png|right|thumb|500px|The three Ketones are interrelated. The body can convert between AcAc and BOHB, but AcAc spontaneously decomposes into Acetone.]]
 
The [[Ketogenic Diet]] produces three types of Ketone, Acetoacetic acid (AcAc), Acetone, and Beta-hydroxybutyrate (BOHB).  
 
The [[Ketogenic Diet]] produces three types of Ketone, Acetoacetic acid (AcAc), Acetone, and Beta-hydroxybutyrate (BOHB).  
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There are three important ketones involved in [[Ketogenic Diet]]s.
 
 
* '''Acetoacetic acid (AcAc)'''. AcAc is the ketone that is produced by the liver from fats and can be metabolized to provide energy. It could be considered the most directly useful of these ketones to the human body. However, AcAc lowers the blood pH, causing potential acidosis. AcAc spontaneously decomposes into Acetone (the half-life is 11.7 hours at 27c<ref name="HayBond1967"/>).  
 
* '''Acetoacetic acid (AcAc)'''. AcAc is the ketone that is produced by the liver from fats and can be metabolized to provide energy. It could be considered the most directly useful of these ketones to the human body. However, AcAc lowers the blood pH, causing potential acidosis. AcAc spontaneously decomposes into Acetone (the half-life is 11.7 hours at 27c<ref name="HayBond1967"/>).  
 
* '''Acetone'''. Generally is often believed to be a waste product, but it has now shown to be metabolically active<ref name="Reichard-1979"/><ref name="Kalapos-1999"/>. It is excreted through the breath and urine, which can sometimes be detected as a fruity smell. Radio-tagged Acetone has been shown to be converted to glucose, fats and protein, but not other Ketones<ref name="Reichard-1979"/>. Acetone levels are one possible [Ketogenic Mechanism of Action| mechanism of action]] behind the success of the [[Ketogenic Diets for Epilepsy]]<ref name="Kalapos-2007"/>.
 
* '''Acetone'''. Generally is often believed to be a waste product, but it has now shown to be metabolically active<ref name="Reichard-1979"/><ref name="Kalapos-1999"/>. It is excreted through the breath and urine, which can sometimes be detected as a fruity smell. Radio-tagged Acetone has been shown to be converted to glucose, fats and protein, but not other Ketones<ref name="Reichard-1979"/>. Acetone levels are one possible [Ketogenic Mechanism of Action| mechanism of action]] behind the success of the [[Ketogenic Diets for Epilepsy]]<ref name="Kalapos-2007"/>.
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* '''Beta-hydroxybutyrate (BOHB)'''. Unlike AcAc, BOHB is stable and does not change blood pH, but it cannot be directly metabolized. AcAc is converted to and from BOHB in the liver and muscles, so BOHB forms a 'reservoir' of ketones that can be converted back to AcAc for providing energy<ref name="Musa-Veloso-2002"/>. (Technically BOHB is not a Ketone, but it's normally considered one.)
+
* '''Beta-hydroxybutyrate (BOHB)'''. Unlike AcAc, BOHB is stable and does not change blood pH, but it cannot be directly metabolized. AcAc is converted to and from BOHB in the liver and muscles, so BOHB forms a reservoir of ketones that can be converted back to AcAc for providing energy<ref name="Musa-Veloso-2002"/>. (Technically BOHB is not a Ketone, but it's normally considered one.)
 
=Ketone Metabolism=
 
=Ketone Metabolism=
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Ketones are used by most tissues in the body with the exception of those cells that have few or no mitochondria which are dependent on glucose<ref name="Westman-2003"/>.  
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Ketones are used by most tissues in the body with the exception of those cells that have few or no mitochondria and so are dependent on glucose<ref name="Westman-2003"/>.  
 
* Cells with no mitochondria include erythrocytes, cornea, lens, and retina.
 
* Cells with no mitochondria include erythrocytes, cornea, lens, and retina.
 
* Cells with few mitochondria include renal medulla, testis, and leukocytes.
 
* Cells with few mitochondria include renal medulla, testis, and leukocytes.

Revision as of 06:15, 10 December 2014

The three Ketones are interrelated. The body can convert between AcAc and BOHB, but AcAc spontaneously decomposes into Acetone.

The Ketogenic Diet produces three types of Ketone, Acetoacetic acid (AcAc), Acetone, and Beta-hydroxybutyrate (BOHB).

  • Acetoacetic acid (AcAc). AcAc is the ketone that is produced by the liver from fats and can be metabolized to provide energy. It could be considered the most directly useful of these ketones to the human body. However, AcAc lowers the blood pH, causing potential acidosis. AcAc spontaneously decomposes into Acetone (the half-life is 11.7 hours at 27c[1]).
  • Acetone. Generally is often believed to be a waste product, but it has now shown to be metabolically active[2][3]. It is excreted through the breath and urine, which can sometimes be detected as a fruity smell. Radio-tagged Acetone has been shown to be converted to glucose, fats and protein, but not other Ketones[2]. Acetone levels are one possible [Ketogenic Mechanism of Action| mechanism of action]] behind the success of the Ketogenic Diets for Epilepsy[4].
  • Beta-hydroxybutyrate (BOHB). Unlike AcAc, BOHB is stable and does not change blood pH, but it cannot be directly metabolized. AcAc is converted to and from BOHB in the liver and muscles, so BOHB forms a reservoir of ketones that can be converted back to AcAc for providing energy[5]. (Technically BOHB is not a Ketone, but it's normally considered one.)

1 Ketone Metabolism

Ketones are used by most tissues in the body with the exception of those cells that have few or no mitochondria and so are dependent on glucose[6].

  • Cells with no mitochondria include erythrocytes, cornea, lens, and retina.
  • Cells with few mitochondria include renal medulla, testis, and leukocytes.

2 See Also

3 References

  1. ↑ RW Hay, MA Bond, Kinetics of the Decarboxylation of Acetoacetic acid, Australian Journal of Chemistry, volume 20, issue 9, 1967, pages 1823, ISSN 0004-9425, doi 10.1071/CH9671823
  2. ↑ 2.0 2.1 GA. Reichard, AC. Haff, CL. Skutches, P. Paul, CP. Holroyde, OE. Owen, Plasma acetone metabolism in the fasting human., J Clin Invest, volume 63, issue 4, pages 619-26, Apr 1979, doi 10.1172/JCI109344, PMID 438326
  3. ↑ MP. Kalapos, Possible physiological roles of acetone metabolism in humans., Med Hypotheses, volume 53, issue 3, pages 236-42, Sep 1999, doi 10.1054/mehy.1998.0752, PMID 10580530
  4. ↑ MP. Kalapos, Possible mechanism for the effect of ketogenic diet in cases of uncontrolled seizures. The reconsideration of acetone theory., Med Hypotheses, volume 68, issue 6, pages 1382-8, 2007, doi 10.1016/j.mehy.2006.10.041, PMID 17166670
  5. ↑ K. Musa-Veloso, SS. Likhodii, SC. Cunnane, Breath acetone is a reliable indicator of ketosis in adults consuming ketogenic meals., Am J Clin Nutr, volume 76, issue 1, pages 65-70, Jul 2002, PMID 12081817
  6. ↑ Westman, Eric C., John Mavropoulos, and William S. Yancy Jr. "A review of low-carbohydrate ketogenic diets." Current atherosclerosis reports 5.6 (2003): 476-483.
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