The Nature of Alcohol

Alcohol molecules are made in many living cells as a by-product of breaking down sugar molecules for their chemical energy. Most cells then break down the alcohol molecules to extract their energy content too. The great exception to this rule is certain yeasts, which excrete alcohol into their surroundings. Like the lactic acid in cheeses and pickled vegetables, like the powerful aromas in herbs and spices, the alcohol in wine and beer is a defensive chemical weapon, which the yeasts deploy to protect themselves against competition from other microbes. Alcohol is toxic to living cells. Even the yeasts that make it for us can only tolerate a certain amount. The pleasant feeling that it gives us is a manifestation of the fact that it’s disrupting the normal function of our brain cells.