The intake of fibre in the diet of a child or an adult, through various foods (such as wholegrain foods, nuts, fruits and vegetables), plays an important role in reducing the risk and lowering the incidence of numerous diseases. The interest of researchers and consumers in the role of diet in the prevention or treatment of many illnesses, and maintaining the general and oral health, has been growing lately. The aim of our study was to underline the role of dietary fibre through its effects on many aspects of the human body and metabolism. Evidence has been found that dietary fibre from whole foods or supplements may reduce the risk of cardiovascular disease by improving serum lipids and reducing serum total and low-density lipoprotein (LDL) cholesterol concentrations in adults and children. Increased fibre content decreases the glycaemic index of foods, which leads to a significant improvement in glycaemic response. High fibre intake is associated with reduced risk of colorectal and breast cancer. In contemporary children, the reluctance to chew raw, hard plant foods may result in a risk of malocclusion and a lack of tooth wear, which cause the need for orthodontic intervention. Fibre consumption is associated with high nutritional value and antioxidant status of the diet, enhancing the effects on human health.