Effect of a natural high fibre diet on blood lipids and intestinal transit time in man

In two experiments with young healthy volunteers the effects of a high in take of dietary fibre on blood lipids and intestinal transit time were investigated. In the first experiment the effects were studied of a high-fibre diet, in which half of the dietary fibre was provided by vegetables and fruits and the rest came from bread and other cereal products. In the second trial the effects of dietary fibre derived from vegetables and fruits were compared with those of isolated citrus pectin and wheat bran. It is concluded that—at least in short-term controlled experiments—fibre-rich food-stuffs have only a small (vegetables and fruits) or no (bran) favourable effect on the level of serum cholesterol. However, in uncontrolled circumstances, a ‘natural’ high fibre diet may through its low fat and cholesterol content indirectly reduce the concentration of serum cholesterol. A high-fibre diet with vegetables and fruits as well as a diet with bran shorten the intestinal transit time and enhance faeces production.