The study by Professor Andrew Smith at Cardiff University revealed that a diet which includes wholemeal cereals has a marked effect on mental health.
The research set out to examine the effect of breakfast cereals on human fatigue and the results of Prof Smith's studies showed that cereal eaters were less stressed and enjoyed quicker thought processes.
Figures show that the diets of up 80% of people in the UK are lacking sufficient fibre.
Volunteers aged from 30-80 years were monitored during a four-week period, eating 40g of high fibre cereal each day.
Findings were apparent within just a week of the trial starting and subjects showed a 10% reduction in fatigue, lower depression scores and better cognitive powers.
Lowering fatigue
Initial research shows that high fibre cereals react positively with the digestive system. "What the cereal is doing is making your gut fitter," explained Prof Smith.
He claimed his research was the first positive link between fibre intake, the digestive system and mental health. But he said more studies were needed.
"Fatigue is extremely prevalent in western societies and procedures that lower it are most welcome," Prof Smith told the journal Appetite.
"Consumption of high fibre cereals may be one simple way of reducing fatigue.
"The physical benefits of a high-fibre diet have been widely acknowledged amongst healthcare professionals for many years. However this is the first time high-fibre intake has been associated with improved mental health."
High fibre diets have previously been linked with prevention of bowel disorders, including cancer.
Kelloggs Head of Nutrition Affairs Dr Kathryn O'Sullivan said the findings were very important.
"It reveals that a bowl of high-fibre cereal is now scientifically shown to have a great impact on physical and mental well being."