A high fibre diet can help make you happier and give you more energy, as well as boosting your mental health, according to a new study from the University of Cardiff in Wales.

A team led by Professor Andrew Smith found that wholemeal cereals, when eaten regularly, can exert a positive effect on a person's mood, and that high fibre eaters are less stressed and can process information quicker than those who consume a low-fibre diet.

Professor Smith compared volunteers aged 30 to 80 over a four-week period. Half were given 40g of high fibre cereal each day while the rest had a 'normal' breakfast.

The results showed that the cereal eaters had better cognitive functions and were less depressed than the control group. The high-fibre diet was also associated with a reduction in fatigue of around 10 per cent.

Writing in the journal Appetite, Professor Smith said: "The correlational results showed that a high fibre intake is associated with less fatigue, emotional distress and fewer cognitive difficulties. This is also the first time high-fibre intake has been associated with improved mental health."