IBD Explained: Causes, Symptoms, And Treatments

Inflammatory bowel disease, or IBD, is a term that refers to conditions that are marked by chronic inflammation of the gastrointestinal tract, per the Mayo Clinic. The most common symptoms of IBD include diarrhea, rectal bleeding, abdominal pain, fatigue, and weight loss. Additionally, IBD quadruples the risk for colon (colorectal) cancer. 

As described by the Centers for Disease Control and Prevention (CDC), the two main types of IBD are Crohn's disease and ulcerative colitis. Although it can occur in any segment of the GI tract, Crohn's disease most commonly targets the section of the small intestine before the large intestine/colon. Inflamed portions of the gut extend into the deeper intestinal layers and are mixed in with areas of healthy tissue. Meanwhile, ulcerative colitis develops in the large intestine (colon) and rectum. The inflammation affects only the innermost lining, typically beginning in the rectum and progressing to the colon. Unlike Crohn's disease, the damaged segments are continuous and not interrupted by normal tissue. 

According to John's Hopkins Medicine, IBD is considered to be an autoimmune disorder wherein the body's immune system mistakenly attacks its own healthy tissues. However, the triggers for IBD have not been identified, and it is not known why only certain people are affected, although people of Jewish ancestry have a higher risk for IBD. IBD is hereditary, but can also occur randomly. It can affect children, particularly teenagers. While there is no cure for IBD, inflammation and symptoms can be reduced. 

As determined by a 2021 systematic analysis published in The Lancet Gastroenterology & Hematology, the prevalence of IBD increased substantially in nearly 200 countries and territories from 1990 to 2017. The researchers report that the global prevalence of IBD is currently (as of 2021) close to 4 million among the female population and nearly 3 million among males, and these numbers continue to rise. 

IBD is more prevalent among people with higher socioeconomic status. This may be related to better diagnostic testing and/or delayed or reduced childhood exposure to common infectious microbes, resulting in an altered immune response in children genetically predisposed to IBD. Since IBD is generally a lifelong condition with high disability, much of the social costs include early retirement, sick leave, and other indirect costs. Thus, notes the researchers, IBD has a considerable impact on healthcare systems, as well as the overall economy. 

Consistent with the findings of the recent systematic analysis above, IBD is more common to industrialized nations, per a report published via StatPearls. Accordingly, North America and Europe have a significantly higher prevalence of IBD than Asia and Africa. Ulcerative colitis tends to be equally distributed between males and females, whereas Crohn's disease is more commonly observed in females versus males. 

As reported by WebMD, IBD results from an interplay between genetic, immune, and environmental factors. A single environmental trigger or combination of triggers (e.g., viruses, bacteria, or antigens), activates an inflammatory immune response in the gut. Since roughly 20% of people with IBD have a family history of the disease, genetics appears to play a role as well. Indeed, since 2006, scientists have identified over 200 regions of the human genome associated with IBD risk. 

While most people who develop IBD are 15 to 30 years old, a second spike in IBD occurs in people over age 60 (via Medical News Today). Other risk factors include the use of nonsteroidal anti-inflammatory drugs (NSAIDs), birth control, and antibiotics. A higher risk of ulcerative colitis, specifically, is associated with people of Jewish heritage. Similarly, smoking is strongly tied to Crohn's disease, doubling the risk. 

The cause of IBD is not fully understood (via ScienceDirect). Evidence suggests that the microbiota (the normal intestinal flora) inappropriately trigger an immune response in the gut that causes severe collateral damage to the intestinal lining. People with a genetic predisposition to IBD are more likely to develop this abnormal immune response. That said, the microbiota may be considered a human organ; in this regard, IBD can be seen as an autoimmune disorder. In autoimmune diseases, the immune system is unable to distinguish between the body's own cells and foreign cells, whereupon the body attacks and damages its own cells by mistake. 

Per WebMD, the goals of medical treatment for IBD are to heal intestinal inflammation to reduce symptoms, stop future flare-ups, and achieve and maintain remission. Initially, doctors often prescribe milder drugs such as aspirin-like anti-inflammatory medications. More potent corticosteroids (NSAIDs) may then be used to quell more persistent inflammation and symptoms. If steroids do not provide sufficient relief, the next-in-line treatment is immunosuppressive drugs, which inhibit the release of inflammation-inducing chemicals from the immune system. Since these drugs may take effect only after 2 to 3 months of use, they are not indicated for severe flare-ups. 

Biologics are high-level therapies for more severe cases of IBD. These treatments (e.g., Remicade, Humira) are essentially antibodies that neutralize other proteins in the body that fuel inflammation. For example, Remicade blocks TNF-alpha, a proinflammatory cytokine produced by immune cells that may trigger the tissue damage associated with Crohn's disease. Clinical trials involving new treatments are an option for IBD patients who do not improve with drug therapies. 

At times, additional drugs and supplements may be recommended for specific symptoms, reports the Mayo Clinic. Antibiotics (e.g., Cipro) may be indicated for infections while anti-diarrheal medications (e.g., Imodium A-D) or fiber supplements such as Metamucil can help alleviate mild to moderate diarrhea. Acetaminophen (e.g., Tylenol) is the drug of choice for pain relief, as opposed to ibuprofen, naproxen, and diclofenac (which can all worsen the disease).  Finally, vitamins and other supplements may be suggested when malabsorption is an issue. 

As reported by WebMD, diet modification mat help improve symptoms of IBD. A low-residue (i.e., low fiber) diet is frequently recommended to alleviate symptoms of diarrhea and abdominal pain. Since this is a very restrictive diet, supplementation with vitamins may be suggested to prevent nutrient deficiencies. Eating small, frequent meals and minimizing dairy products may ease IBD symptoms as well. 

Increasing consumption of oily fish and other foods rich in omega-3 fatty acids and cutting back on processed foods high in omega-6 fats may help suppress inflammation and enhance the gut microbiota (via Johns Hopkins Medicine). Some people with IBD note that they feel better when avoiding gluten, the protein in wheat, rye, and barley. They also report less bloating, cramping, and fatigue on the gluten-free diet. Evidence from some studies supports the use of a diet low in FODMAP to calm IBD symptoms. FODMAP is an acronym that denotes specific carbohydrates (sugars) that are poorly absorbed and digested, resulting in IBD-like symptoms such as gas, bloating, and flatulence. Notably, sorbitol and other sugar-alcohol sweeteners are disallowed on the low FODMAP diet, as they are particularly notorious for aggravating diarrhea. Finally, alcohol and caffeine can potentially provoke IBD symptoms, and may need to be restricted. 

Per a 2018 review in Clinics in Colon and Rectal Surgery, the risk of colorectal (or colon) cancer (CRC) is substantially increased (up to four times) in people diagnosed with IBD before the age of 30. Thus, the longer the disease duration, the greater the risk of CRC. 

Other risk factors for IBD-related CRC include the extent and severity of IBD. For example, increasing length of affected colon increases the risk of CRC; conversely, disease affecting short segments of colon do not increase CRC risk. The degree of inflammation is linked to the risk of cancer as well. Pseudopolyps signify previous severe inflammation and healed damage to the inner lining of the gut. Their presence doubles the risk of CRC within the diseased area. Lastly, a family history of colorectal cancer independently increases CRC risk in IBD patients. 

An article published in a 2021 edition of Frontiers in Pharmacology discussed the contribution of the gut microbiota to CRC risk in IBD patients. There is widespread agreement that gut microbes communicate with the innate immune system and stimulate immune responses. The gut microbiota of IBD patients with CRC is marked by the overgrowth of certain species of bacteria that play a role in the development of IBD and CRC. The use of probiotics to increase levels of favorable bacteria could restore balance to the microbiota and potentially improve the IBD-CRC condition. A key benefit of greater amounts of beneficial bacteria is their production of short-chain fatty acids (SCFAs), which possess anti-inflammatory properties.