The body’s main enzyme for alcohol metabolism, alcohol dehydrogenase (ADH), actually contains zinc at its catalytic site. Zinc is now considered a novel therapeutic approach to alcohol liver disease (ALD). (2) ADH exists in decreased amounts in women, which contributes to less “first-pass metabolism,” and may in part explain why women are more susceptible to alcohol intoxication.
Zinc, an essential trace element, goes hand-in-hand with protein intake; in other words, poor protein intake correlates with poor zinc status. (3) Some symptoms of zinc deficiency include poor growth, infertility, skin disease, and impaired immune function.
The Epidemic of Chronic Alcoholism
Did you know that 50% of the world’s population drinks alcohol, and 5% to 10% have chronic alcoholism? In fact, over 3% of all deaths worldwide are due to alcohol. (4)
Ethanol is the natural product of sugar fermentation by yeasts. According to the USDA, one standard drink contains about half an ounce of ethanol. This is the equivalent of a light 12 oz beer, a 5 oz pour of wine, or 1.5 oz of an 80-proof distilled liquor. Ethanol is found in many household products, such as mouthwash, perfume, and cooking extracts.
The Metabolism of Alcohol
Alcohol is biotransformed to acetaldehyde by three main enzyme systems in the liver. (5)
- The first and main system lies in the cytosol of hepatocytes, where alcohol dehydrogenase (ADH) transforms ethanol to acetaldehyde. As mentioned, the ADHs are actually are actually a class of zinc enzymes!
- The second involves CYPs which oxidize ethanol in the microsomes of cells, known as the microsomal ethanol-oxidizing system (MEOS). Microsomes are basically fragments of hepatocellular endoplasmic reticulum.
- The third involves catalase in the peroxisomes, which acts upon hydrogen peroxide as substrate, metabolizing no more than 5% of all liver ethanol.
Ethanol crosses cell membranes, about 80% of its absorption occurring in the duodenum and 20% in the stomach itself. Peak blood ethanol levels are reached approximately 30 to 90 minutes after a meal. (6) Once ethanol reaches the blood, its taken up mainly by hepatocytes replete with ample quantities of ADH. ADH, however, is also available in the mucosa of the gut.
Zinc Status as a Biomarker of Chronic Alcoholism
Studies looking at evidence of the association of zinc metabolism and alcohol-associated disorders, such as those involving the liver, brain, lung, gut, and even fetal alcohol syndrome, suggest that zinc status should be used as a biomarker for alcohol abuse. (7,8) While it has been confirmed that alcohol induces autophagy in mice, a recent animal study found that adequate zinc intake is required for autophagy. (9)
Given that the body’s main enzyme system responsible for metabolizing alcohol in the liver is zinc-based, there appears to be enough evidence to warrant further studies in zinc supplementation for alcohol-induced diseases.
Alcohol dehydrogenase. Egyptian Journal of Medical Human Genetics.https://www.sciencedirect.com/topics/neuroscience/alcohol-dehydrogenase. Accessed July 17, 2018.
Kharbanda K, Ronis M, Shearn C, et al. Role of Nutrition in Alcoholic Liver Disease: Summary of the Symposium at the ESBRA 2017 Congress. Biomolecules. 2018;8(2):16. doi:10.3390/biom8020016.
Gibson RS. A Historical Review of Progress in the Assessment of Dietary Zinc Intake as an Indicator of Population Zinc Status. Advances in Nutrition. 2012;3(6):772-782. doi:10.3945/an.112.002287.
Alcohol. World Health Organization. http://www.who.int/substance_abuse/facts/alcohol/en/. Published May 12, 2014. Accessed July 17, 2018.
Alcohol Metabolism: An Update. National Institute on Alcohol Abuse and Alcoholism. https://pubs.niaaa.nih.gov/publications/aa72/aa72.htm. Accessed July 17, 2018.
Mitchell MC, Teigen EL, Ramchandani VA. Absorption and Peak Blood Alcohol Concentration After Drinking Beer, Wine, or Spirits. Alcoholism: Clinical and Experimental Research. 2014;38(5):1200-1204. doi:10.1111/acer.12355.
McClain CJ, Su LC. Zinc deficiency in the alcoholic: a review. Alcohol Clin Exp Res 1983;7:5-10.
Skalny AV, Skalnaya MG, Grabeklis AR, Skalnaya AA, Tinkov AA. Zinc deficiency as a mediator of toxic effects of alcohol abuse. European Journal of Nutrition. 2017. doi:10.1007/s00394-017-1584-y.
Liuzzi JP, Narayanan V, Doan H, Yoo C. Effect of zinc intake on hepatic autophagy during acute alcohol intoxication. BioMetals. 2018;31(2):217-232. doi:10.1007/s10534-018-0077-7.