Carbohydrate Metabolism

Have you ever thought how carbohydrate metabolism happens in our body? How carbs are used up by the body and where do the metabolism takes place in our body?

Carbohydrates are ingested; enter into the stomach, and then into the small intestine, where almost all digestion occurs. The principle enzyme that breaks down carbohydrates in the small intestine is amylase. These enzymes then break down carbohydrates into simple sugars such as fructose, galactose, glucose, and smaller chains of glucose molecules (glucose polymers).Carbohydrate Metabolism

These simple sugars are then absorbed through the lining of the small intestine and transported to the liver through the portal vein where the liver then converts all these simple sugars into the common sugar glucose. Glucose is the only usable form of simple sugar in the body.

The liver releases this new glucose into the bloodstream to raise blood sugar levels to where they are supposed to be. If the supply of this newly ingested glucose is too high, it raises the blood sugar level. The excess glucose must be eliminated from the bloodstream. The pancreas houses the hormone insulin. When the blood sugar reaches increasing levels, insulin is released to transport and/or make available the excess glucose to body tissues.  Insulin actually opens up receptor sites on muscles allowing for the uptake of glucose to replenish depleted muscle energy stores. Once glucose is absorbed into the cell it is used for energy, the unused portion of this new glucose is then converted and stored in the muscle as glycogen. Glycogen is then saved in the muscle cells for anaerobic (heavy) activities. It is important to note that muscle tissues can only take up glucose at a gradual rate.

Carbohydrate MetabolismThe liver can only take up glucose at a gradual rate. The liver has the potential to store between 300 and 400 calories of glycogen. When the liver stores are full, and there is still a considerable amount of excess insulin-carried glucose in the bloodstream, it will be taken off and stored as fat in adipose tissue. But here the fat (adipose) cells store blood glucose quite rapidly.

The carbohydrate metabolism in the body involves a series of chemical reactions. Glycogen formation, breakdown of glycogen and glucose to supply energy, formation of glucose to amino acid and glycerols of fat and formation of fat from carbohydrate are the main changes related to carbohydrate metabolism.

Most of the absorbed glucose is oxidized releasing energy. During this process carbon dioxide and water both are also formed. Some portion of glucose is converted to fatty acids and some amount combines with free amino group to form amino acids.

Nutrients responsible for proper carbohydrate metabolism

B Vitamins like thiamine, niacin, riboflavin, pantothenic acid and B6 and from minerals magnesium, and phosphorus are very essential for the proper metabolism of carbohydrates.

Certain hormones like epinephrine, thyroxine, gluoxine, glucagon and islands of Langerhans are essential to maintain normal blood sugar level in a person.

All about Blood Sugar

A healthy person’s blood shows the fasting sugar level as 70-110 mg/100 ml of blood. After a meal it rises to 130-145mg/100 ml of blood. If the blood sugar level is showing above then we would recommend to test for HbA1C test. If it gets positive, then a person is termed as a diabetic patient.

If the carbohydrate intake in the diet is inadequate, it leads to malnutrition and other metabolic disorders. Tissue proteins and fats will be utilized for energy purpose. If excess carbs is taken, it will contribute towards obesity and other metabolic conditions.

Regulation of Blood Sugar

Blood circulates glucose continuously to each and every cell of the body as a source of energy and for the synthesis of a number of substances. From the blood if the glucose is used, then the liver immediately replaces the blood glucose.

If the body is in a good carbohydrate metabolic pathway the Post prandial concentration will fall down to a normal level of 60-85 mgm. The liver very efficiently maintains the normal blood sugar level. If the blood sugar concentration is high this condition is known as “Hypoglycemia”.


Hypoglycemia” occurs when the blood sugar level is below normal levels. This occurs in certain abnormalities of liver function or when insulin is produced in excessive amounts by the pancreas.

Hence, the liver is the only organ in the body which can either supply glucose to the circulation or to remove the excess sugar from the blood.

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