Jay W. Marks, MD, is a board-certified internist and gastroenterologist. He graduated from Yale University School of Medicine and trained in internal medicine and gastroenterology at UCLA/Cedars-Sinai Medical Center in Los Angeles.
Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.
The treatment of IBS is a difficult and unsatisfying topic because so few
drugs have been studied or have been shown to be effective in treating IBS.
Moreover, the drugs that have been shown to be useful have not been
substantially effective. This difficult situation exists for many reasons, as
follows:
Life-threatening illnesses (for example,
cancer,
heart disease , and high blood
pressure), capture the public's interest and, more
importantly, research funding. IBS is not a life-threatening illness and has
received little research funding. Because of the lack of research, an
understanding of the physiologic processes (mechanisms) that are responsible for
IBS has been slow to develop. Effective drugs cannot be developed until there is
an understanding of these mechanisms.
Research in IBS is difficult. IBS is defined by subjective symptoms,
(such as pain), rather than objective signs (for instance, the presence of
an ulcer). Subjective symptoms are more unreliable than objective signs in
identifying homogenous groups of patients. As a result, groups of patients
with IBS who are undergoing treatment are likely to contain some patients
who do not have IBS, and this may negatively affect the results of the
treatment. Moreover, the results of treatment must be evaluated on the basis
of subjective responses (such as improvement in pain). In addition to being
unreliable, subjective responses are more difficult to measure than
objective responses (such as the healing of an ulcer).
Different subtypes of IBS (for example, diarrhea-predominant,
constipation-predominant, etc.) are likely to be caused by different
physiologic processes (mechanisms). It also is possible, however, that the
same subtype may be caused by several different mechanisms in different
people. What's more, any drug is likely to affect only one mechanism.
Therefore, it is unlikely that any one medication can be effective in
most-patients with IBS, even patients with similar symptoms. This
inconsistent effectiveness makes the testing of drugs difficult. Indeed, it
can easily result in drug trials that demonstrate no efficacy (usefulness)
when, in fact, the drug is helping a subgroup of patients.
Subjective symptoms are particularly prone to respond to placebos
(inactive drugs, or sugar pills). In fact, in most studies, 20% to 40% of
patients with IBS will improve if they receive inactive drugs. Now, all
clinical trials of drugs for IBS require a placebo-treated group for
comparison. So, the placebo response means that
these clinical trials must utilize large numbers of patients to detect
meaningful (significant) differences in improvement between the placebo and
drug groups. Therefore, such trials are expensive to conduct.
The lack of understanding of the physiologic processes (mechanisms) that
cause IBS has meant that treatment cannot be directed at these mechanisms.
Instead, treatment usually is directed at the symptoms, which are primarily
constipation, diarrhea, and abdominal pain. These symptoms are not mutually
exclusive since patients may have abdominal pain with either constipation or
diarrhea. Moreover, periods of constipation may alternate with periods of
diarrhea. This variation in symptoms over time can make the treatment of
symptoms complex. The psychotropic drugs (antidepressants) and psychological
treatments (for example, cognitive behavioral therapy) treat hypothetical causes
of IBS (such as abnormal function of sensory nerves and the psyche) rather than
the symptoms.
Abdominal pain is pain in the belly and can be acute or chronic. Causes include inflammation, distention of an organ, and loss of the blood supply to an organ. Abdominal pain can reflect a major problem with one of the organs in the abdomen such as the appendix, gallbladder, large and small intestine, pancreas, liver, colon, duodenum, and spleen.
Diarrhea is a change is the frequency and looseness of bowel movements. Cramping, abdominal pain, and the sensation of rectal urgency are all symptoms of diarrhea. Absorbents and anti-motility medications are used to treat diarrhea.
Gas or "intestinal gas" means different things to different people. Everyone has gas and eliminates it by belching or farting (passing it through the rectum).
Constipation is defined medically as fewer than three stools per week and severe constipation as less than one stool per week. Constipation usually is caused by the slow movement of stool through the colon. There are many causes of constipation including medications, poor bowel habits, low fiber diets, abuse of laxatives, hormonal disorders, and diseases primarily of other parts of the body that also affect the colon.
Fibromyalgia, formerly
known as fibrositis, causes chronic pain, stiffness, and
tenderness of muscles, tendons, and joints without detectable inflammation. Fibromyalgia patients have an unusually low pain threshold. Symptoms of fibromyalgia include fatigue, abnormal sleep, mental/emotional disturbances, abdominal pain, migraine and tension headaches, and irritable bladder. Treatment of fibromyalgia involves patient education, medication, exercise, and stress reduction.
In lactose intolerance, the digestive system cannot digest lactose (the main sugar in milk). Symptoms of lactose intolerance include diarrhea, flatulence, abdominal pain, abdominal bloating, abdominal distention, and nausea. There are several tests to diagnose lactose intolerance. Treatment is generally made with dietary changes, supplements, and adaptation to small amounts of milk.
Small intestinal bacterial overgrowth (SIBO) refers to a condition in which abnormally large numbers of bacteria (at least 100,000 bacteria per ml of fluid) are present in the small intestine and the types of bacteria in the small intestine resemble more the bacteria of the colon than the small intestine. There are many conditions associated with small intestinal bacterial overgrowth, to include: diabetes, scleroderma, Crohn's disease, and others. There is a striking similarity between the symptoms of irritable bowel syndrome and SIBO. It has been theorized that SIBO may be responsible for the symptoms of at least some patients with irritable bowel syndrome. Symptoms of SIBO include: excess gas, abdominal bloating, diarrhea, and abdominal pain.
Dyspepsia (indigestion) is a functional disease in which the gastrointestinal organs, primarily the stomach and first part of the small intestine, function abnormally. It is a chronic disease in which the symptoms fluctuate infrequency and intensity. Symptoms of dyspepsia include upper abdominal pain, belching, nausea, vomiting, abdominal bloating, early satiety, and abdominal distention (swelling). These symptoms are most often provoked by eating.
Digestion is the complex process of turning food you eat into the energy you need to survive. The digestive process also involves creating waste to be eliminated, and is made of a series of muscles that coordinate the movement of food.
Irritable bowel syndrome (IBS) is a functional disease that can affect the quality of those who suffer from this condition. Individuals with IBS can make lifestyle changes that may modify or control the number and severity of episodes. Certain foods, medications, and hormone levels may trigger IBS episodes. Learn how to prevent the number and severity of IBS episodes of diarrhea and constipation.
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