Dietary fibre is a type of carbohydrate found in plant-based foods. It’s not
absorbed or digested by the body, but plays an important role in maintaining good
There are two types of dietary fibre – soluble and insoluble. Most foods contain
both types, but are usually richer in one type than the other.
Soluble fibre: Found in oat, oat bran, linseeds, barley, fruit and vegetable, nuts,
beans, pulses, soya and lentils. ,
Insoluble fibre: Good sources include: whole-wheat bread, bran, wholegrain
cereals, nuts, seeds and the skin of some fruit and vegetables.
Physiological and Metabolic Effects of Fibre Delayed gastric emptying:
Fibres form viscous gel within the stomach, so that the release of the chyme from
the stomach into duodenum is delayed.. Thus nutrient remains in stomach for
longer time and slows down the digestion process. Carbohydrates and lipids that
remain in stomach undergo a slow digestion thus creating a feeling of post prandial
Binding capacity: Mucilaginous fibre such as guargaum, pectin and psyllium
delay glucose absorption, lower blood glucose concentration and affect hormonal
response to their absorbed nutrient. Such effects reduce post prandial blood
glucose concentration and insulin needs and benefial for diabetic patients.
Lowering of serum cholesterol concentration:
With the excretion of bile acids in feces, less amount of bile undergoes for
recirculation. Cholesterol is used for synthesis of new bile acids. The net effect is
lower serum cholesterol. Fibre present in psyllium, guargum, oat and pectin lowers
Role of Fibre in lowering blood glucose levels:
Diet rich in fibre benefits both type 1 and type 2 DM Diet rich in fibre lowers
insulin requirements, increases peripheral tissue sensitivity to insulin, aids in
weight control and lowers blood pressure Soluble fibre as pectin,gums in fruits and
beta glucan in oats increase intestinal trasit time,delay gastric emptying and also
slow rise in blood glucose levels ovear a period of time .Insoluable fibres such as
cellulose and lignins from grains and vegetable decrease intestinal trasit time,
increase fecal bulk, delay glucose absorption and starch hydrolysis. Diet high in
fibre improves glucose metabolism without increasing insulin secretion .They
lower fasting serum and peripheral insulin concentration in response to oral
glucose administration in DM patients.
Role of Fibre in lowering cholesterol levels:
Soluable fibre Present in form of beta glucan content of oats,pectin in
fruits,guargam from beans ,psyllim husk,fibre present in beans and fibre from
fruits and vegetables following effects:
Cholesterol systesis is inhibited by acetic ,propionic and butyric acids
produced by bacterial fermentation.
Clearance of LDL Chol.
Slows gastric emptying and binds bile acids.
Reduces serum fibrinogen and therefor reduce blood clot formation .
Reduces fatty acid absorbtion.
Lower blood pressure by increasing absorption of ccalcium and magnesium.
Akshay Parmar , (M.Sc Biochemistry)