Ketone bodies are the water-soluble molecules containing the ketone group that are produced by the liver from fatty acids during periods of low food intake (fasting), carbohydrate restrictive diets, starvation, prolonged intense exercise, alcoholism, or in untreated type 1 diabetes mellitus. Ketone bodies are readily transported into tissues outside the liver and converted into acetyl-CoA, which then enters the citric acid cycle and is oxidized in the mitochondria for energy. In the brain, ketone bodies are also used to make acetyl-CoA into long-chain fatty acids.
α-Linolenic acid (ALA),, is an n−3, or omega-3, essential fatty acid. ALA is found in many seeds and oils, including flaxseed, walnuts, chia, hemp, and many common vegetable oils.
Cod liver oil is a dietary supplement derived from liver of cod fish (Gadidae). As with most fish oils, it contains the omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Cod liver oil also contains vitamin A and vitamin D. Historically, it was given to children because vitamin D had been shown to prevent rickets, a consequence of vitamin D deficiency.
Carnitine is a quaternary ammonium compound involved in metabolism in most mammals, plants, and some bacteria. In support of energy metabolism, carnitine transports long-chain fatty acids into mitochondria to be oxidized for energy production, and also participates in removing products of metabolism from cells. Given its key metabolic roles, carnitine is concentrated in tissues like skeletal and cardiac muscle that metabolize fatty acids as an energy source. Healthy individuals, including strict vegetarians, synthesize enough L-carnitine in vivo to not require supplementation.
Ketogenesis is the biochemical process through which organisms produce ketone bodies through breakdown of fatty acids and ketogenic amino acids. This process supplies energy under circumstances such as fasting or caloric restriction to certain organs, particularly the brain, heart and skeletal muscle. Insufficient gluconeogenesis can cause hypoglycemia and excessive production of ketone bodies, ultimately leading to a life-threatening condition known as ketoacidosis.
Zellweger syndrome is a rare congenital disorder characterized by the reduction or absence of functional peroxisomes in the cells of an individual. It is one of a family of disorders called Zellweger spectrum disorders which are leukodystrophies. Zellweger syndrome is named after Hans Zellweger (1909–1990), a Swiss-American pediatrician, a professor of pediatrics and genetics at the University of Iowa who researched this disorder.
Fatty acid metabolism consists of catabolic processes that generate energy, and anabolic processes that create biologically important molecules (triglycerides, phospholipids, second messengers, local hormones and ketone bodies). Fatty acids are a family of molecules classified within the lipid macronutrient class. One role of fatty acids in animal metabolism is energy production, captured in the form of adenosine triphosphate (ATP). When compared to other macronutrient classes (carbohydrates and protein), fatty acids yield the most ATP on an energy per gram basis, when they are completely oxidized to CO2 and water by beta oxidation and the citric acid cycle. Fatty acids (mainly in the form of triglycerides) are therefore the foremost storage form of fuel in most animals, and to a lesser extent in plants. In addition, fatty acids are important components of the phospholipids that form the phospholipid bilayers out of which all the membranes of the cell are constructed (the plasma membrane and other membranes that enclose all the organelles within the cells, such as the nucleus, the mitochondria, endoplasmic reticulum, and the Golgi apparatus). Fatty acids can also be cleaved, or partially cleaved, from their chemical attachments in the cell membrane to form second messengers within the cell, and local hormones in the immediate vicinity of the cell. The prostaglandins made from arachidonic acid stored in the cell membrane, are probably the most well known group of these local hormones.
Myristic acid (IUPAC systematic name: 1-tetradecanoic acid) is a common saturated fatty acid with the molecular formula CH3(CH2)12COOH. Its salts and esters are commonly referred to as myristates or tetradecanoates. It is named after the binomial name for nutmeg (Myristica fragrans), from which it was first isolated in 1841 by Lyon Playfair.
Bile acids are steroid acids found predominantly in the bile of mammals and other vertebrates. Diverse bile acids are synthesized in the liver. Bile acids are conjugated with taurine or glycine residues to give anions called bile salts.
Palmitoleic acid, or (9Z)-hexadec-9-enoic acid, is an omega-7 monounsaturated fatty acid (16:1n-7) with the formula CH3(CH2)5CH=CH(CH2)7COOH that is a common constituent of the glycerides of human adipose tissue. It is present in all tissues but, in general, found in higher concentrations in the liver. It is biosynthesized from palmitic acid by the action of the enzyme Stearoyl-CoA desaturase-1.
Phytol is an acyclic diterpene alcohol that can be used as a precursor for the manufacture of synthetic forms of vitamin E and vitamin K1. In ruminants, the gut fermentation of ingested plant materials liberates phytol, a constituent of chlorophyll, which is then converted to phytanic acid and stored in fats. In shark liver it yields pristane.
Refsum disease is an autosomal recessive neurological disease that results in the over-accumulation of phytanic acid in cells and tissues. It is one of several disorders named after Norwegian neurologist Sigvald Bernhard Refsum (1907–1991). Refsum disease typically is adolescent onset and is diagnosed by above average levels of phytanic acid. Humans obtain the necessary phytanic acid primarily through diet. It is still unclear what function phytanic acid plays physiologically in humans, but has been found to regulate fatty acid metabolism in the liver of mice.
Phytanic acid is a branched chain fatty acid that humans can obtain through the consumption of dairy products, ruminant animal fats, and certain fish. Western diets are estimated to provide 50–100 mg of phytanic acid per day. In a study conducted in Oxford, individuals who consumed meat had, on average, a 6.7-fold higher geometric mean plasma phytanic acid concentration than did vegans.
Ethanol, an alcohol found in nature and in alcoholic drinks, is metabolized through a complex catabolic metabolic pathway. In humans, several enzymes are involved in processing ethanol first into acetaldehyde and further into acetic acid and acetyl-CoA. Once acetyl-CoA is formed, it becomes a substrate for the citric acid cycle ultimately producing cellular energy and releasing water and carbon dioxide. Due to differences in enzyme presence and availability, human adults and fetuses process ethanol through different pathways. Gene variation in these enzymes can lead to variation in catalytic efficiency between individuals. The liver is the major organ that metabolizes ethanol due to its high concentration of these enzymes.
Ursolic acid, is a pentacyclic triterpenoid identified in the epicuticular waxes of apples as early as 1920 and widely found in the peels of fruits, as well as in herbs and spices like rosemary and thyme.
Infantile Refsum disease (IRD), is a rare autosomal recessive congenital peroxisomal biogenesis disorder within the Zellweger spectrum. These are disorders of the peroxisomes that are clinically similar to Zellweger syndrome and associated with mutations in the PEX family of genes. IRD is associated with deficient phytanic acid catabolism, as is Adult Refsum disease, but they are different disorders that should not be confused.
In enzymology, a phytanoyl-CoA dioxygenase (EC 1.14.11.18) is an enzyme that catalyzes the chemical reaction
Alpha-methylacyl-CoA racemase (AMACR) is an enzyme that in humans is encoded by the AMACR gene. AMACR catalyzes the following chemical reaction:
A broad classification for genetic disorders that result from an inability of the body to produce or utilize one enzyme that is required to oxidize fatty acids. The enzyme can be missing or improperly constructed, resulting in it not working. This leaves the body unable to produce energy within the liver and muscles from fatty acid sources.
