Aldehyde, any of a class of organic compounds in which a carbon atom shares a double bond with an oxygen atom, a single bond with a hydrogen atom, and a single bond with another atom or group of atoms (designated R in general chemical formulas and structure diagrams). Tao Zeng PhD, Ke-Qin Xie PhD, in Molecular Aspects of Alcohol and Nutrition, 2016. Acetaldehyde is one of the most common indoor and outdoor air pollutants. In addition to ethanol, other xenobiotic precursors of AcH include phenacetin (Brittebo and Åhlman 1984), diethyl ether (Stowell et al. Source: Reproduced with permission from Kwo PY and Crabb DW (2002) Genetics of ethanol metabolism and alcoholic liver disease. The inactive form of ALDH2 is present in about 50% of Orientals. In the body, circulating levels of acetaldehyde are very low and bound to plasma proteins or red blood cells, thereby essentially reducing its toxicity. ALDH2*2 is only about 8% as efficient as ALDH2 in metabolizing acetaldehyde. 5.5 Evaluation. There is sufficient evidence in experimental animals for the carcinogenicity of acetaldehyde. A colourless liquid, it is sparingly soluble in water and highly soluble in ethanol. Chronic alcohol consumption results in high levels of acetaldehyde, which is highly toxic due to a variety of mechanisms including glutathione depletion, oxidative stress, lipid peroxidation and the formation of adducts with proteins.140. It is frequently described as having a tart flavor reminiscent of green apples, and the flavor of dry cider also comes to mind. These statements have not been evaluated by the FDA. There are several varieties of aldehyde dehydrogenase found in the human body. Acetaldehyde is generally found in various plants, ripe fruits, vegetables, smoke from tobacco, gasoline, and exhaust from the engine. 1985). Acetaldehyde is ubiquitous in the ambient environment. Continual exposure to acetaldehyde has been associated with serious long-term health risks, including liver cirrhosis, gastric and esophageal cancers, osteoporosis, and Alzheimer's disease. John Sanseverino, in Encyclopedia of Toxicology (Second Edition), 2005. The concentration difference between the hepatic vein and peripheral veins may be as large as 50 μmol L− 1, implying rapid AcH elimination from the blood. Hi folks! This chemical is toxic, known to cause cancer and a variety of other health problems, and for this reason, most people make an effort to avoid it. Acetaldehyde concentrations can be more than 10 times higher in people with ALDH2 Deficiency. Acetaldehyde (CH3CHO) is a naturally occurring organic compound that is found in everything from ripe fruit to coffee. Analytical results suggest, however, that the normal level of AcH in the blood of rats and humans is very low (<∼0.5 μmol l−1) (Eriksson and Fukunaga 1993; Hobara et al. However, less understood is the concentration in other foods and beverages. Acetaldehyde, produced from the metabolism of ethanol, may also be responsible for localized cancers, brain damage in prenatal infants, and growth suppression (in chicken embryos). Acetaldehyde-protein adducts are toxic to cells. How do I know if I have ALDH2 Deficiency? However, the enzyme that converts ethanol to acetaldehyde works faster than that which converts acetaldehyde to acetate, leading to a build-up of acetaldehyde if you have several drinks in a row. Under normal circumstances the acetaldehyde formed in the human body by the metabolism of alcohol is destroyed almost as soon as it is formed. Acetaldehyde (ethanal) is an aldehyde that is highly reactive and toxic. Kuykendall, in Comprehensive Toxicology (Third Edition), 2018. On the contrary, FA was found at appreciable levels (∼80 μmol l−1) in the blood of unexposed rats, monkeys, and humans (Section 8.16.2.1.1) (Casanova et al. It can create 'Free Radicals', which react with other molecules and cause oxidative damage. Acetaldehyde generated by the metabolism of alcohol is oxidized to acetate; again, this occurs predominantly in the liver. The enzyme alcohol dehydrogenase is found in the liver and stomach that catalyzes the ethanol into acetaldehyde (a toxic compound) that is further broken down to acetic acid and eventually to carbon dioxide and water. 1985), due to its rapid metabolism. 2017 Dec;41(12):2093-2099. doi: 10.1111/acer.13509. 95–129. Hepatic acetaldehyde therefore increases with chronic ethanol consumption. Acetaldehyde is a colorless flammable chemical compound which appears in the form of a liquid with a distinctive fruity odor. Acetaldehyde is ubiquitously present and increased levels are associated with neurological pathologies such as stroke, Wernike encephalopathy, and Alzheimer disease, as well as alcohol-induced impairment of brain structure and function. Acetaldehyde occurs naturally in coffee, bread, and ripe fruit, and is produced by plants. In addition, deoxyribose 5-phosphate is converted to AcH and glyceraldehyde 3-phosphate during catabolism of DNA by deoxyriboaldolase (Kornberg 1980; Metzler 1977). Also, a study of 818 heavy drinkers found that those who are exposed to more acetaldehyde than normal throu… There are carcinogens specific to tap water, basil, beer and mustard. Acetaldehyde is a powerful poison, considerably more toxic than alcohol, and is capable of damaging almost any part of the body. Metabolism takes place in the liver to a number of metabolites and some unchanged acetaldehyde that can be excreted in the urine. Metabolic or autoxidation pathways lead to the formation of endogenous acetaldehyde, and a large number of genes function in the metabolic detoxication of acetaldehyde. A diet higher in sugars can lead to an overgrowth in Candida albicans populations, which convert more sugar into acetaldehyde in the gut. Acetaldehyde from Diet. Tells how alcohol is broken down and converted into acetaldehyde by liver enzymes and other enzymes in the body, as well as how acetaldehyde is converted into an acetic acid radical. Fermented foods - Acetaldehyde is created by microorganisms during the fermentation process so it can be found in fermented foods, such as: Vinegar; Yogurt; Cheese; Sour cream; Fish products; Soy products; Pickled or canned vegetables; Fruit - Acetaldehyde can be found naturally in some fruits, such as: Melon (including watermelon and Oriental melon) Pineapple; Orange; … Acetaldehyde is the proximate metabolite generated by ethanol metabolism by liver ADHs, CYP2E1 originally referred to as the microsomal ethanol oxidizing system (MEOS), and catalase pathways. To learn how Essential AD2 improves liver health, click here. The odor threshold of acetaldehyde is 0.05 parts per million (ppm) (0.09 mg/m 3). What is acetaldehyde? The principal cause of the toxic effects of strong drink. The sheer number of enzymes involved in the metabolism and detoxication of acetaldehyde and other aldehyde species is a testament to the impact of its reactivity. Acetaldehyde from Diet. It is also found in certain household paints and in wood ceilings. Roshanna Rajendram, ... Victor R. Preedy, in Neuropathology of Drug Addictions and Substance Misuse, 2016. Accordingly, the effects of acetaldehyde, after its systemic or central administration and as obtained following ethanol metabolism, looked as they were extensively characterized. Acetaldehyde is found in alcohol, smoke, air pollution, and certain foods & beverages. A Group 1 carcinogen, acetaldehyde can cause damage in our bodies and continued exposure can lead to cancer and other disease. • In the body, circulating levels of acetaldehyde are very low and bound to plasma proteins or red blood cells, thereby essentially reducing its toxicity. It binds to phospholipids, amino acid residues, and sulfhydryl groups. Similar to formaldehyde, if we tried to completely remove this chemical compound from our diet, we would say goodbye to a lot of healthful and nutrient-dense foods like bananas, lemons, apples, and milk. The main source of acetaldehyde is the consumption of alcohol. Cancer-causing PCBs are found in … M. Shimada, ... A. Sanyal, in Pathobiology of Human Disease, 2014. It is also produced by the partial oxidation of ethanol by the liver enzyme alcohol dehydrogenase and is a contributing cause of hangover after alcohol consumption. We use cookies to help provide and enhance our service and tailor content and ads. Acetaldehyde is the most common toxin in cigarette smoke and is the cause of many of the negative health risks associated with cigarette smoking. AcH is produced from naturally occurring compounds as well as from xenobiotics, most notably ethanol. AcH is produced from threonine in mammals by the enzyme threonine aldolase, which converts threonine to glycine and AcH (Harper et al., 1977; White et al., 1978). Most of the free acetaldehyde is excreted in the exhaled breath. Table 6. Those with ALDH2 Deficiency should be aware of the major sources of acetaldehyde. In our modern environment, acetaldehyde enters the body from a number of sources. High concentrations may be achieved locally in the liver during alcohol abuse. Pathways of exposure include air, water, land, or groundwater, as well as drink and smoke. The molecular formula identifies each type of element by its chemical symbol and identifies the number of atoms of each element found in one discrete molecule of the substance. Acetaldehyde also can damage the lining of your mouth, throat, and stomach. A significant increase of acetaldehyde in hepatic venous blood reflects the high tissue level of acetaldehyde. 1985). Copyright © 2021 Elsevier B.V. or its licensors or contributors. The acetaldehyde is then attacked by another enzyme, acetaldehyde dehydrogenase, and another substance called glutathione, which contains high quantities of cysteine (a substance that is attracted to acetaldehyde). The presence of ALDH in most tissues may reduce the toxic effects of acetaldehyde. When outside, acetaldehyde is used in a variety of different work environments and can be released into the air through production or transportation. This product is not intended to diagnose, treat, cure, or prevent any disease. Second-hand smoke is a major contributor to indoor air acetaldehyde. Acetaldehyde (CH3CHO) is a volatile compound found in wine. It is the last precursor in yeast fermentation before ethanol is formed, and is produced when pyruvate, the end product of glycolysis, is converted by the enzyme, alcohol dehydrogenase (ADH), to acetaldehyde. The acetaldehyde generated from consuming alcoholic beverages is also considered to be a Group I human carcinogen. To learn which foods are high in acetaldehyde, visit Acetaldehyde in Foods. The reaction is catalyzed in the liver by the enzyme alcohol dehydrogenase. Anti-oxidants in human cells can protect from oxidative damage, but the anti-oxidants need to be regenerated to continue to function properly. As ADH is not physiologically active in the brain, the CYP2E1 should play important roles in the conversion of ethanol to acetaldehyde in the rodent brains.35 Therefore, the CYP2E1 gene polymorphisms may influence individual susceptibility to AD by altering the metabolism of ethanol to acetaldehyde in the brain. As a result, acetaldehyde leads to the failure of DNA repair, mitochondrial abnormalities, impairment of microtubular function, and failure of the cell membrane. Foods high in acetaldehyde. Following inhalation exposure, acetaldehyde is deposited in the nasal cavity and upper respiratory tract, and eventually some traces can be absorbed into the blood and be distributed throughout the body. Classes of aldehyde dehydrogenase isoenzymes. The uptake of acetaldehyde in the nasal cavity is influenced by its solubility and inspiratory flow rate. Acetaldehyde is also found in automobile and diesel exhaust fumes, making it prevalent in the air of densely populated cities. Acetaldehyde, acrolein, and formaldehyde are the principal toxic aldehydes present in cigarette smoke and contribute to the risk of cardiovascular disease and noncancerous pulmonary disease. Acetaldehyde vapor can be metabolized in the nasal cavity by the mixed-function oxidase and carboxylesterase systems. Paraldehyde is the cyclic trimer of acetaldehyde molecules. Acetaldehyde is a toxic molecule that is always circulating in the blood in low concentrations. It is a “naturally occurring carcinogen” found in most fruits and many vegetables. This conversion is catalyzed by aldehyde dehydrogenase (ALDH) and is accompanied by reduction of NAD+ (Figure 3). Acetaldehyde is also found in automobile and diesel exhaust fumes, making it prevalent in the air of densely populated cities. AcH is produced from naturally occurring compounds as well as from xenobiotics, most notably ethanol. Acetaldehyde is the particular compound that’s been implicated in hangovers. It is ubiquitous in the environment and may be formed in the body from the breakdown of ethanol. The accumulation of acetaldehyde may account for the flushing seen with alcohol consumption in heterozygotes. The acetaldehyde is then attacked by another enzyme, acetaldehyde dehydrogenase, and another substance called glutathione, which contains high quantities of cysteine (a substance that is attracted to acetaldehyde). The accumulation of acetaldehyde is influenced by the catalytic activities of these enzymes. Malondialdehyde-Acetaldehyde (MAA) Protein Adducts Are Found Exclusively in the Lungs of Smokers with Alcohol Use Disorders and Are Associated with Systemic Anti-MAA Antibodies Alcohol Clin Exp Res. It also cause abnormal muscle development. When tobacco is burned, acetaldehyde is produced and enters the smoke, which is then inhaled. A product of alcohol metabolism that is more toxic than alcohol itself, acetaldehyde is created when the alcohol in the liver is broken down by an enzyme called alcohol dehydrogenase. So even organically grown foods also contain naturally occurring carcinogens, in fact, they contain many different natural carcinogens. 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Of formaldehyde that is always circulating in the air come from building materials, flooring paints! Impact on our health radicals can damage proteins and DNA, which gives acetaldehyde its properties. For short periods of time, typically 2-4 hours of Toxicology ( Third Edition ), 2013 about. Efficient as ALDH2 in metabolizing acetaldehyde that is found in everything from ripe fruit to coffee catalytic activities of enzymes...