What is Malabsorption?
Malabsorption is defined as an inability to absorb nutrients from foods. Nutrients typically reach the blood stream via the mucosal membrane of the small intestine. 

Symptoms such as gas and bloating, fatty stools (steatorrhea), as well as diarrhea and cramping, are caused by both a decrease in nutrients in the blood stream, as well as the increase passage of all that is unabsorbed through the digestive tract.

Some report unusually foul smelling stool that is lighter in colour and 'sticky', meaning it will stick to the side of the bowl, difficult to flush. Stool may or may not also contain undigested food. Individuals who suffer from malabsorption, know it can be extremely uncomfortable and due to explosive and or urgent diarrhea, how greatly it can impact all aspects of an individual's life.

What causes Malabsorption?
Malabsorption disorders can be caused by a number of problems, and is not a diagnosis in and of itself, but rather a symptom of an underlying gastrointestinal pathology. Disorders preventing adequate mixing of food with digestive enzymes are one example. Diseases of the pancreas, as in cystic fibrosis or chronic pancreatitis, can cause a significant decrease in enzymes such as lipase, protease and amylase, essential for the break down of fats, protein and carbohydrates/sugars. High levels of (HCL) acid in the stomach, decreased bile production via the liver (as in biliary obstruction or chronic liver failure), as well as unbalanced gut flora, can all impact how food is broken down and nutrients are absorbed. As can lactase deficiency, in which an individual produces insufficient lactase enzyme to break down lactose (a sugar) found in many dairy products.

Malabsorption can also be caused by injuries to the lining of the small intestine. The small intestine has small projections called villi lining its walls. Each villi has its own set of small projections called microvilli. These serve in exponentially increase the surface area with which the small intestine can absorb nutrients. Celiac sprue is one example of disorders that impairs this process. In celiacs, tests reveal that the villi are flattened, no longer functioning to increase absorption. Some drugs, like neomycin (an antibiotic), and even alcohol can also destroy the villi of the small intestine, greatly impacting our ability to absorb nutrients from our diet.

Some conditions slow the muscle contractions (peristalsis) of the intestine. Contents then pools in one place, allowing excess bacterial growth (and fermentation, which also produces gas). This throws off the delicate balance and what was once a healthy bacteria, supporting digestive processes, becomes 'bad' due to overgrowth and can impact the nutrients we are able to extract. Conditions such as IBS can cause bouts of increased contraction (spastic colon) alternating with decreases in peristalsis. This is why individuals with IBS have the characteristic diarrhea – constipation – diarrhea cycle. When contractions are increased and food is pushed through too quickly, there is again, malabsorption.

How do I know if I have malabsorption?
There are a number of tests you can do to determine if you are not optimally absorbing nutrients from your diet, and why. An endoscopy is perhaps the most invasive methods, in which a tube is fed through the mouth – an esophagogastroduodenoscopy can assess the esophagus and stomach (for ulcers due to high HCL) or the duodenum, to assess abnormalities in the lining of the mucosal membrane of this portion of the small intestine. Biopsies can also be taken during these procedures. The remainder of the small intestine can be examined via enteroscopy. One of the initial tests ordered is usually the fecal fat test, in which the stool is tested to determine the percentage of fat that is passing through unabsorbed. Greater than 7g/day is said to be a hallmark of malabsorption. Further testing will be required to assess cause (barium x-ray, upper endoscopy, colonoscopy). Stool tests for elastase and chymotrypsin can also distinguish pancreatic from GI causes of malabsorption. IBS is a diagnosis of exclusion, meaning that if none of the above findings are present and the individual suffers from gas, bloating, cramping, diarrhea (sometimes alternating with constipation), they are usually given a diagnosis of irritable bowel syndrome.

The Food Allergy Connection
Something else to consider is that food allergies/sensitivities can cause essentially the same symptom picture, or exacerbate another existing malabsorptive condition. If there are foods that you know make symptoms worse, you may want to do an elimination challenge. By eliminating the offending foods for a period of 3-4 weeks, and then reintroducing, you can isolate which specific foods/food groups need to be avoided due to allergy or sensitivity. Symptoms should decrease greatly, if not disappear altogether once the foods have been eliminated. In the case of sensitivity, after a period of avoidance, you may be able to slowly bring some of these foods back into your diet, in moderation, without reaction.