Alcohol intake is affected by both environmental and inherited biological mechanisms. In the early history of alcohol research, caloric interactions were among the most intensely studied of the environmental factors, and a large body of evidence was obtained that indicated that nutrition can affect alcohol drinking. Much of this evidence still stands today but appears to have been largely overlooked and to be in danger of being forgotten. Nevertheless, alcohol is not only a pharmacological substance but also a nutrient. As a nutrient it influences the metabolism of most tissues in the body, with especially marked effects on glucose homeostasis. Alcohol has a high energy content, and this energy is utilized by the body as efficiently as the energy in normal food. Ethanol has such good properties as a substrate for energy production that we are faced with the problem of explaining, not why it is consumed, but why it is not consumed in still larger quantities by nonalcoholic humans or by animals. When alcohol is consumed by animals, the intake of food decreases in relation to the caloric content of the alcohol; if a choice of macronutrients is possible, alcohol decreases the consumption of carbohydrates most. The interaction between alcohol and food intake goes both ways, however, with the intake of different foods also influencing alcohol consumption. For example, a high carbohydrate/low protein diet depresses alcohol intake, whereas a low carbohydrate/high protein food increases it. If such specific diets can help to depress alcohol intake, nutritional therapy might be useful in the treatment of alcohol abusers, probably not as the primary treatment, but perhaps as an adjunct to other forms of treatment.