Carbohydrate Intolerance

Carbohydrate Intolerance: Overview

Alternative names: Carbohydrate Malabsorption

Carbohydrate intolerance is the inability to digest certain types of carbohydrate due to a lack of digestive enzymes.  Those with carbohydrate intolerance find it very difficult to properly digest some or all carbohydrates, especially breads, pastas, and fruits.

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When carbohydrates are consumed, our bodies normally break them down into basic sugar molecules so that they can be transformed into energy.  In those with carbohydrate intolerance, the enzymes that are needed to metabolize carbohydrates (such as salivary amylase, pancreatic amylase, maltose, and alpha-galactosidase) are not as abundant as they should be.

The digestive systems of those who don't have enough enzymes sometimes aren't able to keep up with demand, particularly when a lot of carbohydrates are consumed at once.

Starches and sugars are not absorbed properly because they are broken down only partially, or not at all, during digestion.  This hampers the release of 'quick energy', as well as the digestion of other nutrients.  Unprocessed carbohydrates passing through the digestive tract can cause a number of problems ranging from mild cramps to severe blockages.

The sugar lactose, which makes up 2-8% of milk, is also considered a carbohydrateLactose intolerance is therefore a type of carbohydrate intolerance.

Causes and Development

Enzyme deficiencies can be hereditary (this is rare), acquired (primary), or secondary.

Acquired lactase deficiency (i.e. developed later in life) leads to the most common form of carbohydrate intolerance: lactose intolerance.  Lactase levels are high in newborns, allowing them to digest milk.  In most ethnic groups (80% of blacks and Hispanics, and over 90% of Asians), lactase levels decrease after weaning, causing older children and adults to be unable to digest significant amounts of lactose.  However, 80-85% of Caucasians produce lactase throughout life and are thus able to digest milk and milk products.

Secondary lactase deficiency occurs secondary to conditions which damage the small-bowel mucosa.  Examples include Celiac Disease, Tropical Sprue, and acute gastrointestinal infections.

Signs and Symptoms

Symptoms of carbohydrate intolerance include:

Symptoms may be worse after eating a re-heated starchy meal.  Re-heating changes molecular structures, causing starch to turn into a "resistant starch".  This type of starch cannot be digested by the small intestine and so passes into the large intestine, where it is broken down.  This in turn often produces offensive gas, abdominal cramping, and bloating.

Diagnosis and Tests

Diagnosing carbohydrate intolerance can be difficult because symptoms often overlap with a number of other bowel and digestive problems.

Reducing intake of dietary starches can help determine if carbohydrate intolerance is causing symptoms.  Slowly reduce intake of highly-processed foods such as refined-flour products (pasta, white bread, etc.), pre-packaged cookies, cakes, pies, etc., replace them with healthier foods, and see if that makes a difference.

A confirmed diagnosis is generally made via a hydrogen (H2) breath test: the patient breathes into a device that breaks down the chemical composition of each breath.  Hydrogen levels are measured, and are usually low when carbohydrates are being properly digested; when they're not, the digestive tract often expels excess hydrogen in the breath.  Before taking the test, the patient usually has to eat carbohydrate-rich food(s) just before being tested.

Treatment and Prevention

Treatment consists of modifying the patient's diet so as to avoid foods that cause digestive problems.

Digestive Enzymes: A digestive enzyme supplement containing pancreatin and betaine can aid in the digestion of carbohydrates.  Pancreatin helps supplement the salivary amylase necessary to digest these foods, and betaine increases stomach acid naturally, which improves overall digestion.  An enzyme containing alpha-galactosidase will also aid the digestion of both simple and complex carbohydrates.

Probiotics: Probiotics containing lactobacillus acidophilus can help reduce the digestive discomfort associated with carbohydrate malabsorption.  However, it is important not to overdose on probiotics, especially if you have trouble digesting carbohydrates.


Carbohydrate intolerance can lead to hyperinsulinemia, in which the body becomes unable to properly manage the sugars and starches in the diet.

Under normal circumstances, the pancreas should release just the right amount of insulin needed to process the sugar that results from eating a particular carbohydrate.  Hyperinsulinemia causes the pancreas to release a disproportionate amount of insulin; continued release of excess insulin results in sugar being processed too quickly and blood glucose levels dropping too low (hypoglycemia).

Over time, more and more insulin is needed to process even small amounts of carbohydrates and it becomes ineffective at delivering the sugar to the cells where it is needed.  This is when insulin resistance develops.

Hyperinsulinemia can also cause the adrenal gland to over-produce the stress hormone cortisol, resulting in adrenal burnout or adrenal fatigue.

Hypertension is another possible consequence of hyperinsulinemia.  According to a study published by The American Heart Association, there is increasing evidence that insulin resistance/hyperinsulinemia may play a key role in the development of hypertension in cases of abnormal carbohydrate metabolism.

High blood cholesterol: Triglycerides often become elevated due to consuming excessive carbohydrates that cannot be properly metabolized.

Polycystic Ovarian Syndrome: The liver uses a specific enzyme system to convert cholesterol into a master steroidal hormone called pregnenolone, from which hormones such as progesterone, DHEA, and testosterone are derived.  An imbalance in these hormones may result in polycystic ovarian syndrome.

Chronic Pain and Inflammation: Lack of sufficient nutrients and overtaxed adrenals may result in chronic muscle and joint inflammation.

Type II Diabetes: Adult-onset diabetes has been directly linked to carbohydrate intolerance.

Stroke: According to Stroke Magazine, hyperglycemia is considered a significant risk factor for stroke.

Obesity: Among those who are obese and have difficulty losing weight, carbohydrate malabsorption may be the cause.

Heart Disease: Contrary to popular opinion, it is high insulin levels and not high cholesterol levels that are the most common indicators of impending heart disease.

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Carbohydrate Intolerance:

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