Dietary fibres refer to plant carbohydrates like cereals, legumes and green leafy vegetables. These fibres cannot be digested by us. Fibres hold water. So, they swell up and act like a sponge in our gut. In the gut, they increase the dietary bulk and transit time. Fibres also prevent heart disease, high cholesterol and blood glucose levels, constipation, obesity and colon cancer. These fibres might have some negative effects on nutrition by binding trace metals like calcium and zinc and preventing their proper absorption. It is advised that 40 grams of dietary fibres should be consumed daily.