A considerable proportion of waking life is devoted to the use of the brain in the solution of problems. Inadequate diet and substance abuse inhibit performance of the brain.
Laboratory tests indicate substantial improvement in non-verbal intelligence, by supplementing the diets with minerals and vitamins. It is as yet uncertain how general and how important this effect may be. Several studies have found significant correlations between indices of alcohol consumption and measures of cognitive function (abstract problems, problem solving and memory tests) among moderate drinkers. Alcohol can damage cell membranes in the brain and can impair the absorption and metabolism of vitamins, in particular vitamin B1 which is important for the function of brain enzymes.