Most of the alcohol you drink is absorbed through the duodenum (small intestine), from which it flows through a large blood vessel (the portal vein) into your liver. There, an enzyme similar to gastric ADH metabolizes the alcohol, which is converted to energy by a coenzyme called nicotinamide adenine dinucleotide (NAD).
NAD is also used to convert the glucose you get from other carbohydrates to energy; while NAD is being used for alcohol, glucose conversion grinds to a halt!
(*) Your liver cannot process both glucose, and alcohol at the same time!
The normal, healthy liver can process about 1⁄2 ounce of pure alcohol (that’s 6 to 12 ounces of beer, 5 ounces of wine, or 1 ounce of spirits) in an hour.
The rest flows on to your heart.
(Taken from the book entitled, “Nutrition for Dummies” 4th Edition page 118)
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