Do Humans Over-consume Salt to Improve Mood

Study 1. 120 young adults will be were recruited. They will arrive in the laboratory at 0900 having consumed their normal breakfast. Over the morning they will reported their mood by responding to one hundred millimetre visual analogue scales anchored with the words: Composed/Anxious; Hostile/Agreeable; Elated/Depressed; Unsure/Confident; Energetic/Tired; Confused/Clearheaded. These dimensions of mood came from the factor analysis that formed the basis of the Profile of Mood State questionnaire. An overall measure of mood will be calculated. .

Randomly they will receive either a 150ml glass of water, or an equivalent volume of water containing electrolytes (in total 150mg sodium chloride and 45mg potassium chloride (Gatorade G2 Low calorie (34 kcal) Thirst Quencher, Pepsico). This drink will be consumed for a first time after 50 minutes, and a second time after 140 minutes. A estimate of habitual salt preference will be gained by responding to questions concerning the adding of salt to meals and a preference for salty foods.

Study 2: One hundred and twenty young adults will be recruited. A second study attempts to replicate the first in a double-blind trial where the taste of salt was hidden by using a capsule. . Participants will be assigned to one of four experimental conditions; 1) swallowed placebo capsules; 2) swallowed capsules containing electrolyte (300mg sodium chloride); 3) received placebo capsules and plain water; 4) received capsules containing electrolyte and plain water. Each drink will be 150ml of water. The allocation of the type of capsule will be carried out double-blind, determined by computer generated random numbers.

Otherwise the procedure will be identical to study one.