The small intestine is a pink tube-shaped organ lined with muscle. It is about 20 feet long on average (can vary from 15 to 30 feet) and about one inch in diameter. The top is connected to the stomach and the bottom is attached to the large intestine. To move food along, the intestines normally contract about a dozen times a minute. Digestion begins by chewing and breakdown in the stomach, but the majority of further digestion and nutrient absorption occurs in the small intestine where various additional enzymes that break down nutrients are introduced. Food is transformed into glucose (sugar), fatty acids (fats), amino acids (protein) and a myriad of micronutrients. All these nutrients pass through the thin walls of the intestine via nutrient absorbing projections (villi) into the bloodstream. Water-soluble nutrients (carbohydrates, amino acids, water-soluble vitamins) are absorbed by transport across brush border cells through passive and active transport systems. Fat soluble nutrients (fat soluble vitamins such as A, D, E and K / fatty acids) must first undergo emulsification with bile and are then taken into the lymphatic system for later association with plasma proteins. For proper nutrient absorption, the intestine’s mucous membrane lining must be healthy. If not, absorptive pathways can develop defects, leading to deficiencies of nutrients. The mucosal barrier is also a defense against unwanted toxins, antigens, and sick microbes.
Malabsorption occurs when one of the many steps of digestion are disrupted. Causes, sometimes overlapping, include
- Food doesn’t get broken down properly. Pancreas or liver problems can diminish production of digestive enzymes or bile needed for digestion, making nutrient absorption incomplete or lacking.
- Excessive sick bacteria in the small intestine may interfere with digestion.
- Damage to the intestinal lining interferes with absorption. Certain drugs, many toxins, excessive alcohol consumption, and over processed non-foods, as well as celiac disease, Crohn’s disease, other diseases, and radiation therapy for cancer, can cause damage to the lining.
- Some forms of obesity.
- Surgery that shortens the amount of the small intestine available to absorb nutrients.
Signs of malabsorption include: abdominal bloating and gas, weight loss, chronic diarrhea or loose stools, more stool volume than usual, excess fat in stools ( pale looking, extra foul smelly, bulky, greasy). Other symptoms are specific to nutrient deficiencies. In older adults, symptoms can be subtle and more difficult to recognize. Nutritional support to the lining of the small intestine, pancreas or liver and measures to reduce sick bacterial overgrowth can be provided. A quality digestive enzyme or bile salts supplement taken with meals can aid digestion and other problems such as celiac disease, lactose intolerance or leaky gut require dietary changes. Boosting nutrient intake to help make up for the deficits resulting from malabsorption and to support intestinal repair can correct or ward off serious deficiencies and resultant disorders. Unbalanced diets, typified by the highly processed low fiber Western diet, alter intestinal barrier function and promote a leaky gut and consequential problems. A healthful real food diet rich in non-digestible but fermentable fiber components can definitely help. Zinc and nucleic acids (such as ribonucleic acid) are among the nutrients that help prevent and heal injury. Glutamine, the most abundant amino acid in the body, plays several important roles in the intestine. For example, glutamine regulates protein metabolism and intestinal inflammation among other mechanisms.