Written by Marcia Zimmerman, CN. Learn about the remarkable role of the gut in the body. 

The gastrointestinal tract is the largest interface between the inside and outside of the body. Totaling nearly 30 feet in length from mouth to anus, the gut will process approximately 60 tons of food during a lifetime. (1)  The gut contains many specialized areas for digesting, absorbing, processing, and eliminating food. Beginning with the mouth, these include the esophagus, stomach, small intestine, colon, rectum and anus. The gut lining or mucosa harbors tiny glands that produce digestive enzymes. Accessory digestive glands and organs including the salivary glands, liver and pancreas secrete juices that convert food into products that can be ferried via the bloodstream to all body tissues.

The remarkable gut is so complex, scientists call it the gut microbiome. It is an “organ” in the truest sense of the word, weighing in at approximately 5 pounds. (2) The gut microbiome has an intimate symbiotic (mutually beneficial) relationship with your body. (3)  It helps the body maintain homeostasis, a state of balanced metabolism under varying environmental conditions. The body provides a warm environment and food for the microbiome. How does this cozy arrangement play out? Let’s take a closer look.

Gut Feelings

Did you know that your gut has a brain? The enteric (gut) nervous system, which controls the digestive conveyer belt (peristalsis), is an intricate network in the gut wall that carries on bi-directional communication with the brain. The enteric nervous system is influenced by hormones, neurotransmitters, and central nervous system connections that affect gut muscle contractions, mucosal function, and blood vessels in the digestive tract. (4) Powerful emotions evoke both increased and decreased stomach secretions, depending upon the individual. (5)  Stress also affects gastric function because it disturbs the balance between the enteric neurotransmitters acetylcholine, which is calming and norepinephrine which is stimulating. (6)  Some familiar sensations that can accompany stressful episodes are tummy grumbling, gas, bloating and visceral (internal organ) pain. These effects have been amply demonstrated in animal studies. (7)

When under stress, it may be helpful to use a full spectrum digestive enzyme formula with everything you eat. Keep in mind that you need to be mindful of what you are eating. If what you are about to eat is merely to stop the rumbling in your tummy – but doesn’t excite your palate – you are cheating yourself from one of life’s greatest pleasures. You are also risking good digestive health.

Tummy Matters

At birth, the human gut is sterile. It will be colonized by some 500 to 1,000 kinds of bacteria that outnumber all the cells in your body, perhaps by as much as a factor of 10. (8)  The bacteria (microbiota) that make up the gut microbiome have many functions with duties being assigned to specific species of bacteria. They release essential amino acids from undigested food for absorption, synthesize vitamins and short-chain fatty acids, and break down sugars (xylose, pectin, arabinose, mannose, fructose, and galactose) many of which human enzymes cannot breakdown. Even for those enzymes we do produce, the microbiota boost overall digestive enzyme power. (9)

One of the most important functions of the microbiota is immune regulation. Immunoglobulin A (IgA) is the most abundant immune protein in all mucosal surfaces. It protects the body against pathogenic (disease causing) bacteria. IgA secretion from colonic mucosa has been found in animal models to be modified by the previously mentioned enteric neurotransmitters acetylcholine and norepinephrine. (10)  It has been found that norepinephrine and dopamine, selectively stimulate certain pathogenic bacteria. (11)  This further supports the idea that stress, which increases these neurotransmitters in the brain and gut, stimulates the growth of pathogenic bacteria.

Constipation is one of the most common complaints in the United States. More than 4 million Americans have frequent constipation, accounting for 2.5 million physician visits a year. (12) Constipation is defined as a bowel condition in which feces are dry and hard, and evacuation is difficult and infrequent. It is further categorized as either type A constipation (fewer than three bowel movements per week) or type B, characterized by stool hardness with excessive straining needed to evacuate. (13)

Constipation is not a disease, but may signal some metabolic disturbance or prescription drug interaction. In most cases, constipation can be remedied by making sure you eat five servings of fruits and vegetables each day and cut down on consumption of processed foods and sugar. Adding symbiotic formulas containing both probiotics and prebiotics to your daily regimen helps increase beneficial bacteria and provides soluble fiber to increase stool weight and improve its passage through the colon.

Posted December 4, 2009.  


  1. Hawrelak, J.A.; Myers, S.P. “The Causes of Intestinal Dysbiosis: A Review” Altern Med Rev. 2004;9:180-162.
  2. Lyte, M.; “The Microbial Organ in the Gut as a Driver of Homeostasis and Disease” Med. Hypothesis 2009, Nov 7 [epub ahead of print] PMID 19900764.
  3. Forsythe, P.; et al.; “Mood and Gut Feelings” Brain Behav. Immun. 2009; doi:10.1016/j.bbi.2009.05.058.
  4. Ibid.
  5. Havel, P.J.; “Periphral Signals Conveying Metabolic Information to the Brain: Short-Term and Long-Term Regulation of Food Intake and Energy Homeostasis” Soc Experim Biol Med 2001;1535-3702/01/22611-0963:963-977.
  6. Schmidt, L.D.; et al.; “Autonomic Neurotransmitters Modulate Immunoglobulin A Secretion in Porcine Colonic Mucosa” J Neuroimmunol. 2007;185:20-28.
  7. Berezina, T.P.; Ovsyannikov, V.I.; “Mechanism for the Inhibition of Contractile Activity of the Gastric Antrum and Pylorus in Rabbits During Psychogenic Stress” Bull Exp Biol Med 2008;147:296-300.
  8. Travis, J.; “Gut Check” Science News Online 5/31/03;163 (22).
  9. Gill, S.R.; et al.; “Metagenomic Analysis of the Human Distal Gut Microbiome” Science 2006;312:1355-1359.
  10. Schmidt, D.R.; Mangelsdorf, D.J.; “Nuclear Receptors fo the Enteric Tract: Guarding the Frontier” Nutr Rev. 2008;66(10 Suppl 2):S88-S97. doi:10.1111/j.1753-4887.2008.00092.x.
  11. Freestone, P.E.; Haigh, R.D.; Lyte, M.; “Blockade of Catecholamine-induced Growth by Adrenergic and Dopaminergic Receptor Antagonists in Escherichia coli O157-H7, Salmonella enterica and Yersinia enterocolitica” BMC Microbiology 2007;7:8 doi:10.1186/1471-2180-7-8.
  12. National Digestive Diseases Clearinghouse (NDDC)   http://digestive.niddk.nih.gov/ddiseases/pubs/constipation
  13. Amenta, M.; et al.; “Diet and Chronic Constipation. Benefits of Oral Supplementation with Symbiotic zir fos (Bifidobacterium longum W11 + FOS Actilight” Acta Biomed 2006;77:157-162.