Dietary factors such as the consumption of tryptophan, the precursor of serotonin, or sugar, may play an important role in influencing alcohol-induced impairment. Study I used an amino acid diet to manipulate plasma tryptophan in male social drinkers in a 3 (supplemented, balanced, and depleted tryptophan) x 3 (alcohol, placebo, sober) design with 12 subjects per cell. A variety of mood, memory, and psychomotor performance measures were taken at baseline, five hours after amino acid ingestion, and after alcohol consumption. Strong alcohol effects were produced but no tryptophan, nor alcohol-tryptophan interaction effects were found. / Study II examined the combined effects of sucrose and alcohol in a 3 (100 g sugar, 35 g sugar, 0 g sugar) x 3 (alcohol, placebo, sober) design with 15 subjects per cell. Subjects were tested on tasks similar to those used in Study I at a variety of times following intoxication (i.e., 0.5 hours, 1.5 h, 3.5 h) in order to examine effects when blood glucose peaked as well as at a point when hypoglycemic rebound can occur in some subjects. A strong alcohol x sugar interaction was seen 0.5 h after drinking, with high doses of sugar attenuating intoxication without influencing blood alcohol levels. No hypoglycemia was produced after 3.5 h. / Study III replicated Study II using a simpler design which controlled for the possible effects of aspartame (the placebo sweetener used in Study II). A variety of gastric or central mechanisms, which can account for the finding that sucrose can reduce the intoxicating effects of ethanol, are discussed.

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Indiana University-Purdue University Indianapolis (IUPUI) / Seven human alcohol dehydrogenase genes (which encode the primary enzymes involved in alcohol metabolism) are grouped into classes based on function and sequence identity. While the Class I ADH isoenzymes contribute significantly to ethanol metabolism in the liver, Class IV ADH isoenzymes are involved in the first-pass metabolism of ethanol. It has been suggested that the ability to efficiently oxidize ethanol occurred late in primate evolution. Kinetic data obtained from the Class I ADH isoenzymes of marmoset and brown lemur, in addition to data from resurrected ancestral human Class IV ADH isoenzymes, supports this proposal--suggesting that two major events which occurred during primate evolution resulted in major adaptations toward ethanol metabolism. First, while human Class IV ADH first appeared 520 million years ago, a major adaptation to ethanol occurred very recently (approximately 15 million years ago); which was caused by a single amino acid change (A294V). This change increases the catalytic efficiency of the human Class IV enzymes toward ethanol by over 79-fold. Secondly, the Class I ADH form developed 80 million years ago--when angiosperms first began to produce fleshy fruits whose sugars are fermented to ethanol by yeasts. This was followed by the duplication and divergence of distinct Class I ADH isoforms--which occurred during mammalian radiation. This duplication event was followed by a second duplication/divergence event which occurred around or just before the emergence of prosimians (some 40 million years ago). We examined the multiple Class I isoforms from species with distinct dietary preferences (lemur and marmoset) in an effort to correlate diets rich in fermentable fruits with increased catalytic capacity toward ethanol oxidation. Our kinetic data support this hypothesis in that the species with a high content of fermentable fruit in its diet possess greater catalytic capacity toward ethanol.