Malabsorption - failure to get the goodness from food
The job of the gut is to absorb the goodness from food. To do this, it first has to reduce food particles to a size which allows the digestive enzymes can get at them, then it has to provide the correct acidity for enzymes to work, produce the enzymes,emulsifying agent (bile salts) and move the food along the gut. Finally the large bowel allows growth of bacteria for a final digestive/fermentative process and water extraction.
The gut has a particularly difficult job because it has to identify foods that are safe from potentially dangerous microbes (most are not dangerous but positively beneficial). This explains why 90% of the immune system is gut associated. The innoculation of the gut with the good microbes takes place in the gut in the first few minutes following birth - see Probiotics
Anything which goes wrong with any of these processes can cause malabsorption. Malabsorption means that the body does not get the raw materials for normal everyday work and repair. This means there is the potential for lots of things to go wrong when there is malabsorption.
Malabsorption can occur for the following reasons:
- Failure to chew foods properly.
- Gandhi said we should chew our liquids and drink our foods! It is essential to break foods down into small particles to allow quick and efficient digestion of them. Saliva contains amylase which starts the process of carbohydrate digestion. It also contains epithelial growth factor to prevent leaky gut.
- Not enough acid in the stomach (acid is necessary to start off protein digestion and further digestion of protein takes place in the small intestine) - see Hypochlorhydria.
- Failure to produce enough digestive enzymes (as in cystic fibrosis) - see Digestive enzymes.
- Failure to produce enough bile (blocked bile ducts, eventually causes jaundice, poor liver function). See Gall bladder disease and gall stones.
- Inflammation in the gut caused by gut dysbiosis (i.e. the wrong bugs) or gastroenteritis (temporary bugs in the gut). See Fermentation in the gut and CFS
- Inflammation in the gut caused by allergy (coeliac disease, multiple food allergy, ulcerative colitis and Crohn's).
- Food passing through the gut so quickly that there is not time for digestion to take place: drugs; overuse of laxatives; being very nervous; excessive exercise; autonomic neuropathy, thyrotoxicosis.
- Poisons or toxins in the diet, such as lectins - see Lectins.
- For example, tea drinking causes malabsorption of minerals because tannins in tea bind with minerals to form insoluble tannates which cannot be absorbed. Wheat bran is high in phytic acid, which blocks absorption of minerals. One example of this effect can be found in an area in Iran where wheat is a staple part of the inhabitants' diet. As a result they are zinc deficient. Zinc is necessary for growth and many of these people do not achieve their full potential height and remain as dwarfs.
- Cancer in the gut. This rarely presents with malabsorption, but in its advanced stages it can certainly cause malabsorption.
- Surgery - where sections of the gut have been removed.
Complications of poor gut function
There are two common complications of poor gut function.
- Malabsorption of vitamin B12
- The first is malabsorption of B12. B12 requires a special carrier protein called "intrinsic factor" to be produced in the stomach. B12 binds on to intrinsic factor and is carried to the gut, where it is absorbed in the last section of the small intestine, the terminal ileum. There is lots of potential for things to go wrong and B12 deficiency is common. The problem is that the normal range for B12 is set so low that many of these cases are not picked up. I like to see blood levels for B12 running at at least 600, and I often recommend injections of B12 in order to get levels up around 2000, where it has other beneficial effects over and above its physiological reactions.
- Leaky gut syndrome
- Another problem of poor gut function is leaky gut syndrome. The problem with leaky gut is that molecules get from the gut into the blood stream before they have been fully digested. These large, antigenically interesting molecules in the bloodstream can activate the immune system leading to allergy or possibly autoimmunity. Furthermore, many of these molecules can mimic the action of hormones in the blood stream and have other profound effects. For example, "leaked" food molecules can mimick the actions of the hormone vasopressin which controls blood pressure, thereby causing profound fluctuation in blood pressure. See the test for Short chain polypeptides
Symptoms of malabsorption
Almost any symptom could result from malabsorption, from failure to thrive, weight loss, fatigue, to organ failure.
- Diarrhoea often reflects the disease process causing the malabsorption.
- Stools may have undigested fat in them causing large, offensive, pale, greasy stools which float and are therefore difficult to flush away.
- Blood or excessive mucous in the stool.
- Wind, gas and bloating as a result of fermentation in the gut.
- Offensive wind points to a fermenting gut. See Fermentation in the gut and CFS.
Tests of malabsorption
Any or all of these tests may be needed to work out the cause:
- Faecal fat: measures the level of fat in stools.
- Pancreatic elastase: an indicator of pancreatic function.
- Comprehensive digestive stool analysis: CDSA - this looks at digestion and absorption of fats and proteins, gives us an idea of fermentation in the gut, together with microbial content of the gut. It also looks at faecal occult blood and short chain fatty acid profile. As an extra you can ask for faecal calprotectin (which is a good indicator of gut inflammation), faecal elastase (pancreatic function) and bile salts.
- Short chain polypeptides. This looks at proteins which have leaked from the gut into the blood stream and therefore gives us an indication of leaky gut. I don't do this test very often as it doesn't narrow down a diagnosis very much, but can be useful to help explain otherwise inexplicable symptoms.
- Vascular endothelial growth factor - Salivary test for hypochlorhydria
Treatment of malabsorption
Ideally this needs to be overseen by an experienced physician, but not many are conversant with all of the above issues.
Identify the cause of the malabsorption by going through the above check list and the tests listed below.
Correct any nutritional deficiencies which may have arisen from years of malabsorption. This would initially be achieved through taking my standard regime of Nutritional Supplements, backed up by nutritional screening tests such as B12 and folic acid, ferritin and calcium levels (this is an indication of vitamin D deficiency, all of which can be easily done by NHS blood testing). If the patient does not feel completely restored by these interventions then one would consider more sophisticated tests of nutritional status such as Antioxidant status, B vitamin profile, fat soluble vitamins including vitamin D and Essential Fatty Acids.
- Full blood count
- Elastase - a new test for pancreatic disease
- Comprehensive Digestive Stool Analysis
- Vascular endothelial growth factor (VEGF)- salivary test for hypochlorhydria
- Short chain polypeptides
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