The positive effects of different types of breakfast have long been the subject of speculative theories. Now these have been tested scientifically and reported in the journal Appetite (Vol 22, February 1994) in a paper 'Effects of Breakfast and Caffeine on Cognitive Performance, Mood and Cardiovascular Functioning' by Andrew Smith, Anna Kendrick and Andrea Maben.
Previous research had shown that lunch diminishes performance at tasks demanding alertness, although stable extroverts are better after lunch than neurotic introverts. High carbohydrate lunches make it harder for people to focus their attention, while lunches high in protein make them prone to distractions. Post-lunch impairment can be reduced by caffeine.
Subjects (24 male and 24 female students) arrived early, having abstained from food and caffeine since midnight. After having blood pressure and pulse recorded, they were assigned to three groups: no breakfast, cooked breakfast, and cereal/toast breakfast. The meal (or no meal) ended with either decaffeinated coffee or decaffeinated coffee with added caffeine. After breakfast they were tested for reaction time, vigilance and mood.
One hour after the meal, no significant differences were found, except that cooked breakfasts resulted in an increased pulse rate. After two hours, 'the cooked breakfast group felt more contented, interested, sociable and outward- going than the no breakfast and cereal/toast groups.'
Caffeine raised subjects' blood pressure, increased vigilance after one hour, and reaction times after two hours. The results 'showed no effect of having breakfast, or of breakfast type on performance of sustained attention tasks, and confirmed that in this respect breakfast differs from lunch.'
A further series of experiments was conducted involving memory and logical reasoning tasks, although cereal and toast were now off the menu, leaving a choice between cooked breakfast and nothing.
Tasks of memory and reasoning led to more interesting results. Whereas breakfast was found to improve subjects' abilities to remember words from a long list, it impaired performance on a test of logical reasoning. 'These results clearly demonstrate that conclusions about the effect of breakfast on performance will depend on the type of task the person carries out.'
Caffeine was found to improve performance, although 'it should be noted that the caffeine dose used here was considerably higher than would be normally consumed in a real-life situation.'Reuse content