OPTIMIZE YOUR HEALTH
Integrated Approach to Gastrointestinal Disorders

What Does Endocrinology Have to Do with the Gastrointestinal Tract Anyway?
By Jannet Huang, MD, FRCPC, FACE

You may be wondering why an endocrinologist is writing an article about bowel health. Let’s learn about how our endocrine system affects bowel health. You may not be aware that your bowels actually produce a lot of different kinds of hormones. The gastrointestinal (GI) tract has been called the largest endocrine organ because of its complement of endocrine cells. These cells produce a variety of chemical transmitters that are involved in gastrointestinal motility, secretion, absorption, growth, and development. Many hormones play various roles. Incretins (eg. GLP-1) regulate our energy and glucose metabolism. Hormonal signals include ghrelin, neuropeptide Y and peptide YY, which allow the gut and the brain (specifically the hypothalamus) to communicate to help regulate appetite and energy homeostasis.

Aside from producing hormones, the GI tract can also manifest symptoms of endocrine diseases. Examples include constipation in hypothyroidism, loose / frequent bowel movement in hyperthyroidism, and abdominal pain / nausea in adrenal insufficiency. Many women will also notice bowel habits fluctuating with they menstrual cycle as well.

Irritable bowel syndrome (IBS) is a chronic condition of the gastrointestinal tract. Its cardinal symptoms are abdominal pain and altered bowel habits. IBS is the most commonly diagnosed gastrointestinal condition and is second only to the common cold as a cause of absence from work. An estimated 10 to 20 percent of people in the general population experience symptoms of IBS, but only about 15 percent of affected people actually seek medical help.

A number of theories as to the origin of IBS have been proposed over the years. However, despite intensive research, no cause has been consistently identified. One theory suggests that IBS is caused by abnormal contractions of the colon and intestines (hence the term "spastic bowel," which has sometimes been used to describe IBS). The development of IBS following severe gastrointestinal infections (such as those caused by Salmonella or Campylobacter) has been well recognized for many years. The mechanisms by which the infections trigger the development of IBS are not well understood. Most patients with IBS do not have a history of having had one of these infections. It is known that stress and anxiety have a number of effects on the intestine; thus, it is likely that anxiety and stress worsen symptoms, but they are probably not the sole cause of symptoms. Some studies have suggested that IBS is more common in people who have a history of physical, verbal, or sexual abuse. Food intolerances are common in patients with IBS, raising the possibility that IBS is caused by food sensitivity or allergy. This theory has been difficult to prove, although it continues to be studied. The best way to detect an association between symptoms of IBS and food sensitivity is to eliminate certain food groups systematically (a process called an elimination diet), which is usually best accomplished under the supervision of a doctor or nutritionist.

Many researchers believe that IBS may be caused by heightened sensitivity of the intestines to normal sensations (so-called "visceral hyperalgesia"). This theory proposes that nerves carrying sensory messages from the bowel are overactive in people with IBS, so that normal amounts of gas or movement in the gastrointestinal tract are perceived as excessive and painful.

IBS is also commonly associated with other conditions such as fibromyalgia, chronic fatigue syndrome, interstitial cystitis, etc.

Treatment of IBS

GI conditions also provide good examples illustrating why mind-body medicine is so important. Stress, along with other lifestyle factors such as diet, exercise and sleep, affect our bowel health. To attain optimal bowel health, an integrative approach is necessary.

There are a number of different treatments for IBS. Many of these measures can be combined to effectively reduce the pain and other symptoms of IBS. Because of the wide variability of symptoms in people with this condition, different therapies work for different people. Treatment is usually a long-term process; during this process, it is important to maintain good communication with your doctor about your symptoms, your concerns, and any psychological and social issues that arise.

• Monitoring —close monitoring of symptoms to help identify factors that worsen IBS
  
  
• Dietary modification
  
  
• Increasing dietary fiber — (see Supplement Cabinet)
  
  
• Exercise — Many patients find that daily exercise can be extremely helpful to their sense of well-being. Exercise can also have favorable effects on bowel action.
  
  
• Psychosocial therapies — Stress and anxiety can worsen IBS. Some patients benefit from formal counseling with or without pharmacologic therapy or other treatments such as hypnosis and biofeedback. Participation in a support group can also be valuable.
  
  
• Drugs — Although many drugs are available to treat the symptoms of IBS, these drugs do not cure the condition, and they are used primarily to support other types of treatment. The choice among these drugs depends in part upon whether a person has diarrhea, constipation, or pain predominant IBS. Furthermore, the effectiveness of specific drugs varies from one person to another. As a general rule, drugs are reserved for patients whose symptoms have not adequately responded to more conservative measures. Types of medications used include anticholinergic drugs, antidepressants, anxiolytic drugs and drugs affecting serotonin receptors which are used specifically for IBS.
  
  
  • The drugs that block serotonin receptors are best suited for people with diarrhea-predominant symptoms. The first that received approval from the Food and Drug Administration was alosetron (Lotronex). Alosetron was withdrawn from the market soon after its introduction because of concerns related to its safety, but was later reintroduced under tight regulatory control. Whether other drugs in this class will prove to be safer remains to be determined.
    
    
  • On the other hand, Tegaserod (Zelnorm) is the first of the stimulating category of drugs to be approved by the Food and Drug Administration. In clinical trials, it appeared to be moderately effective for women with constipation-predominant symptoms.
    
    
  • Rifaximin (Xifaxan), an antibiotic that is not absorbed systemically, has been found to be helpful for the flatulence and bloating associated with IBS.  Rifaximin does not produce any systemic side effects since its being non-absorbable confines its effects within the intestinal tract.

Not all patients with IBS are alike, and it is important a to be evaluated by a team that knows you as a whole person. Since IBS is a condition that is affected by our lifestyle, both physical and psychological factors, an integrative approach should be utilized.

Internet Resources

• National Institute of Diabetes and Digestive and Kidney Diseases
• The American Gastroenterological Association
• The American College of Gastroenterology
• International Foundation for Functional Gastrointestinal Disorders

—July 2006

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