Digestion is the systematic break down of food substances by enzymes to release the nutrients contained therein. The nutrients are absorbed mostly in the small intestine.
The residue, containing dietary fibre, travels along the large intestine until it reaches the rectum and later voided. The time taken for food to travel from the mouth to the rectum for voiding is called transit time.
Transit times have been found to be shorter in communities eating high fibre diet than those eating low fibre diets. This is because fibre absorbs water and swells, increasing the bulk of the intestine content which facilitates faster movement.
This faster movement may lead to decrease in absorption of nutrients particularly in the small intestines since the contents do not stay long enough for more nutrients to be absorbed.
When the chyme or intestinal contents get to the large intestine, digestion and absorption would have been completed. However, water is absorbed mostly at the colon.
High fiber diet reduces the amount of energy absorbed of food in the small intestine because there is less time for digestion and absorption.
According to Winter, high fibre diet may alter the types and number of bacteria in the bowel and possibly inhibit their production of carcinogens.
Moreover, low fibre diets are said to have low satiety value. Low fibre diets lead to constipation. This is due to decrease in frequency of bowel movements resulting to prolonged transit time.
During this period of delay, water absorption into the blood continues, resulting in a hard stool which is difficult to pass. Inadequate fluid intake and loss of muscle tone added to this problem.
So, diets with high fibre content is far better tha diets with low fibre content.
REFERENCES
Brownsell, V. I. Griffith, C. J. and Eleri, J. (1992). Applied Science Food Studies. Longman Science & Technical; UK.
Fox, B. A. and Cameron, A. G. (1989). Food Science, Nutrition and Health. 5th ed. Edward Arnold; A Division of Hodder &Stoughton, London.
No comments:
Post a Comment