Carbohydrate Malabsorption / Intolerance

Carbohydrate Malabsorption / Intolerance

Carbohydrate Malabsorption / Intolerance

If your baby suddenly develops diarrhea, and yet appears to be well, the reason could be carbohydrate malabsoption. Learn which foods are linked to malabsorption problems, and what you can to do if your baby is affected.

What is carbohydrate malabsorbtion?

Carbohydrates are the sugars and starches found in milk, foods (including juices) and some medications.

In order for the body to be able to absorb carbohydrates onto the blood stream (to then be used for energy) they need to first be digested (i.e. broken down into simpler sugars) by the relevant digestive enzymes - lactase, maltase, isomaltase, or sucrase. 

Due to either an insufficient production of a digestive enzyme or to the presence of indigestible carbohydrates contained in our diet, some carbohydrates are malabsorbed ... and this will lead to gastric symptoms.

What foods can cause problems? 

While the only carbohydrate in breast-milk is lactose, formula or starting solids introduces various other carbohydrates such as fructose, sorbitol, sucrose and starches.

Fruit juices containing sorbitol or a high ratio of fructose-to-glucose (prune, apple and pear juice) can result in chronic diarrhea, flatulence, bloating, and abdominal pain in some infants and children.

Prune 14.0 2.3 0.6 12.7
Pear 6.6 1.7 1.7 2.1
Apple 6.0 2.3 2.5 0.5
Orange 2.4 2.4 4.7 0
Grape 6.5 6.7 0 trace
Pineapple 1.4 2.3 7.9 0
Peach 1.1 1 1.7 0.9


Eating whole fruits does not cause the same intensity of gastric symptoms because the fiber contained in the fruit (but removed from fruit juice) slows down the digestive process allowing more time for adequate digestion and absorption of the sugars.

Malabsorption of sugars and starches found in some foods can also result in gastric symptoms. These foods include sugars such as raffinose in beans; fructose in onions, artichokes, pears and wheat; sorbitol in fruits such as apples, pears, peaches, and prunes; and starches found in potatoes, corn, noodles, oats and wheat. 

NOTE: Although lactose intolerance is also a carbohydrate malabsorption disorder, information on this condition is covered more comprehensively in a separate article.

Signs and symptoms

If a carbohydrate (sugar or starch) is not adequately digested, this means that it will continue to pass though the intestines (rather than be absorbed into the blood stream, as it would if it were digested). Once it reaches the large bowel, it draws in extra fluid into the bowel by a process called osmosis. The bacteria normally present in the bowel, ferment the undigested carbohydrates and as a result gastric symptoms may develop. The symptoms include:

  • watery diarrhea;
  • abdominal distension or bloating;
  • cramps;
  • excessive gas.

Fruit juices containing sorbitol (an alcoholic sugar found in many fruits) may be associated with carbohydrate malabsorption without typical gastric symptoms.  Rather the symptoms may include...

  • Increased physical activity and irritability 

NOTE: The malabsorption of carbohydrates that can result from large intakes of juice is the basis for some health care providers to recommend juice for the treatment of constipation.

Who is affected?

Carbohydrate malabsorption is common in infants and young children as their capacity to absorb some sugars and starches is more limited than an adult's.

Carbohydrate malabsorption (often referred to as intolerance) is particularly common in infants younger than 3 months of age due to an immature digestive system and an incomplete development of their intestinal flora.

What you can do to help!

  • Avoid starting solid foods too early.
  • Avoid early introduction of fruit juices with sorbitol or a high fructose-to-glucose ratio to all young children - especially infants who have had colic.
  • If you are already offering fruit juice to your baby on a regular basis, try ceasing this for a period of time. Offering water at these times instead.
  • Substituting grape juice for apple juice may eliminate diarrhea in some children. White grape juice contains equivalent amounts of fructose and glucose without sorbitol and is better absorbed.
  • Dilute all fruit juices provided for infants and young children to at least 50% or more.

Written by Rowena Bennett.

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