What to Know About IBS Blood Tests

There is no single cause of irritable bowel syndrome (IBS). Instead, a variety of factors contribute to a person’s symptoms. Some common contributors to IBS include abnormal muscle contractions in the intestine and dysfunction in the nervous system. Stress, changes in the gut microbiome or a severe bacterial infection could also lead to the development of IBS. 

Regardless of the cause, some of the characteristic symptoms of IBS include diarrhea, bloating and constipation. When experiencing symptoms of IBS, it is helpful to discuss them with a healthcare provider. In addition to a physical exam, doctors can help to evaluate symptoms by ordering diagnostic tests, such as an antibody blood test for IBS

When making an IBS diagnosis, healthcare providers will ask about past experiences with food poisoning. This is because a previous case of food poisoning may indicate a specific type of IBS, known as post-infectious irritable bowel syndrome (PI-IBS). An IBS blood test is a reliable way to determine if a food-related infection led to the development of irritable bowel syndrome. With a diagnosis of PI-IBS from a blood draw, healthcare providers can create a more personalized treatment strategy. Medications, lowering stress and a low FODMAP meal plan are all ways to help to reduce symptoms of diarrhea, bloating or constipation. 

Understanding more about gut bacteria and the common toxins that harm the gut will help people to envision how food poisoning develops into IBS. It also helps to explain just why IBS blood tests are so effective in evaluating the risk for PI-IBS. To grasp the benefits of bloodwork for IBS, first learn more about how post-infectious IBS develops. 

What Is Post-Infectious Irritable Bowel Syndrome (PI-IBS)?

Post-infectious irritable bowel syndrome (PI-IBS) is a form of IBS caused by food poisoning. The term “post-infectious” means that the IBS was caused by a foodborne illness. A few different gastric infections can lead to symptoms, but they are all more commonly known as “food poisoning.” 

There are three main types of IBS: IBS-D (diarrhea predominant), IBS-C (constipation predominant) and IBS-M (diarrhea-constipation mixed). Post-infectious IBS almost always includes symptoms of diarrhea, which means patients are either suffering from IBS-D or IBS-M. For the healthcare provider, a diagnosis of IBS-C means it is less likely there is a presence of PI-IBS. 

A significant body of research shows a link between food poisoning and IBS, especially IBS-D. A recent review by the Mayo Clinic of over 45 studies revealed that one in every nine patients (11 percent) who get a case of food poisoning will also develop the hallmark symptoms of IBS. That amounts to over five million people per year who will develop the condition as a result of food poisoning. For this reason, cases of food poisoning are a leading known contributor to irritable bowel syndrome. 

How Food Poisoning Develops into IBS 

When food poisoning develops into IBS, it is usually due to a toxin called Cytolethal Distending Toxin B, or CdtB. It is released by all of the most common bacteria that causes food poisoning like Salmonella, Shigella, E. coli, Campylobacter, and C. difficile. These bacteria release the toxin CdtB into the body, which plays a role in making people sick. 

When the body detects the presence of CdtB, it responds by releasing an antibody. In this case, it is anti-CdtB. However, CdtB and a protein in your gut called vinculin share a similar structure. They can look alike in the body, so the immune system may think it needs to fight back against vinculin instead. This is why it may also produce another antibody in addition to the anti-CdtB, such as anti-vinculin. 

Unfortunately, the production of anti-vinculin is an autoimmune response and leads to both gut nerve damage and improper gastrointestinal functioning, which then presents itself as IBS-D or IBS-M. Symptoms may include abdominal discomfort, loose stools and gas. 

It is also important to know that IBS can develop long after the initial bacterial infection. Symptoms of IBS-D or IBS-M may not present themselves until more than a month after the food poisoning incident. Some people will not even remember the gastrointestinal event that led to their IBS symptoms. This is why healthcare providers may order the IBS blood test regardless of whether patients remember food poisoning or not. 

How to Evaluate the Risk of PI-IBS 

According to the Centers for Disease Control and Prevention (CDC), 48 million people per year get food poisoning in America. Patients of all ages can get food poisoning and develop post-infectious irritable bowel syndrome. 

Since PI-IBS presents itself as IBS-D or IBS-M, it is possible to have a case of post-infectious irritable bowel syndrome if the person: 

  • Experiences chronic diarrhea or a mix of symptoms of diarrhea/constipation 
  • Has abdominal pain and bloating 
  • Had a case of food poisoning in the past (may have been mild; may or may not remember)

It is always a good idea for a physician to investigate for PI-IBS even if there is not a significant gastrointestinal event like food poisoning. It is possible to validate IBS symptoms or the presence of PI-IBS through a doctor-ordered antibody blood test. Patients can even order the test during a virtual visit or request a testing kit for their next appointment.  

How Blood Tests Validate the Presence of PI-IBS  

It is helpful to use blood testing technology to validate the presence of conditions like PI-IBS which can increase your chances of getting food poisoning again, and will only worsen your symptoms. Blood tests help to validate the presence of PI-IBS by measuring scientifically validated biomarkers in blood. The test will measure the levels of the two biomarkers we’ve discussed, anti-CdtB and anti-vinculin, since we know they are both reliable biomarkers for detecting IBS from food poisoning. If either antibody measures above the test’s threshold, doctors are able to diagnose post-infectious IBS-D or post-infectious IBS-M with up to 100% certainty (positive predictive value).

There are many types of blood tests in the healthcare world, but the only licensed antibody test for IBS is known as ibs-smart™. This unique test was developed by physicians at Cedars-Sinai Hospital in Los Angeles. The ibs-smart™ test can accurately and quickly diagnose IBS and confirm its root cause – food poisoning. A biomarker-based IBS diagnosis can also help to prevent unnecessary diagnostic procedures, such as colonoscopies.

Click here to learn more about ibs-smart™ IBS blood test kits


How to Care for Post-Infectious IBS 

There are many ways to treat both IBS-D and IBS-M. To create a treatment plan, healthcare providers consider a few different factors, including blood tests results, gastrointestinal symptoms, current medications and overall health. According to Monash University, some treatment options for PI-IBS include: 

  • Antibiotics: There are a few different FDA-approved antibiotics to treat IBS symptoms. Some have shown more consistency in easing symptoms than others. It is important to discuss the pros and cons of each medication with a healthcare provider, including medication interactions and side effects.

  • Other Medications: Doctors may prescribe anti-diarrheal medications to help ease symptoms. Antidepressant medications and serotonin receptor antagonists may also reduce symptom severity and discomfort.

  • Dietary Modification: Low-fermentation diets, such as the Low-FODMAP diet, are shown to be effective in the treatment of IBS symptoms. Start by learning more about what FODMAP is and consider making an appointment with a healthcare professional or a qualified dietitian to discuss dietary options. 

Some people are interested in probiotics for gut health. The idea is that the presence of probiotic bacteria and yeasts helps to keep the gastrointestinal system and other parts of the body healthy. More research needs to be done on the benefits of probiotics, specifically for IBS. However, Harvard Health says it may be worth it to try probiotics for IBS to help reduce abdominal pain, fecal urgency and bloating. Before you begin any new probiotic regimen, consult with a trained dietitian. They can help determine which supplemental probiotic strain is beneficial for a person’s specific symptoms of IBS. 

What Is a Low-FODMAP Diet? 

We know that foods of all kinds can trigger or worsen IBS symptoms. Specialized modifications in the diet can play an important role in treating patients who have IBS. Some common diet adjustments include reducing gluten and fiber, avoiding sulfuric foods and reducing the consumption of alcoholic beverages. Even with these changes, patients may still find it difficult to determine what makes their IBS worse. For many healthcare providers, the first step for patients like these is to eliminate foods that are known as “FODMAPs.” 

A high-FODMAP food is a common culprit of IBS symptoms. FODMAPs are poorly absorbed and highly fermentable, which means they do not completely digest in the small intestine. When they do not break down properly in the body, they can lead to symptoms such as abdominal pain, bloating, gas, diarrhea and constipation. Garlic, onion, beans and apples are examples of popular, healthy foods that are also commonly associated triggers with abdominal pain and IBS. 

With the help of dietary modification, it is possible to identify if foods like these are causing IBS symptoms. The next step is removing them from the diet to alleviate discomfort. Discovering which foods cause disruption in the gut is important in designing the right long-term IBS diet plan. This is why the most popular diet treatment for IBS is an expertly-crafted menu of low fermentable (low-FODMAP) foods. 

The American College of Gastroenterology Clinical Guideline for Managing Irritable Bowel Syndrome recommends “a limited trial of a low-FODMAP diet in patients with IBS to improve global symptoms.” Patients who are new to a low FODMAP diet may find benefit in a low-FODMAP meal delivery service that makes it easy to get started on a low-fermentable food plan.  

How to Start a Low-FODMAP Diet 

Complete FODMAP elimination is challenging for most people, which is why a low-FODMAP program can be so helpful. It is rooted in science and based on Monash University’s research which shows that up to 75 percent of people feel better when using a low-FODMAP diet to treat their IBS symptoms. It is also meant to be temporary, which means that an initial restriction in foods will allow for more freedom to eat with less IBS symptoms in the future. 

With the help of ModifyHealth’s low-FODMAP program, the entire process of elimination and reintroduction takes around eight weeks. While it requires participants to eliminate foods and introduce them in phases, the process makes it possible to eventually expand dietary possibilities and enjoy many more foods both safely and comfortably. Upon finishing the eight-week program, it is possible to create a balance between FODMAPs that are well-tolerated and those that are not. An elimination diet assists in preventing the triggers that make PI-IBS worse while introducing an impactful way to take control of dietary choices.

It is also not the right choice for those with eating disorders or those who are currently underweight. For those who have preexisting conditions or do not know the cause of their digestive health issues, it is a good idea to speak to a doctor first before beginning any new meal plan. After being cleared by a healthcare provider, it is possible to try options like low-FODMAP meal plans and low-FODMAP meal delivery. 

Low-FODMAP Meal Plans for IBS 

After finding out the reason behind IBS, it is time to find ways to reduce and relieve symptoms. A helpful way to decrease diarrhea, bloating, abdominal pain and constipation is to begin with a low-FODMAP elimination and reintroduction protocol from ModifyHealth. Discovering the foods that contribute to digestive issues will make it possible to incorporate them more healthfully and responsibly, creating an impactful strategy for dealing with PI-IBS symptoms. This information also makes it easy to order fully prepared low-FODMAP recipes for every meal. Receive weekly, chef-curated meals at your doorstep and eliminate the burden of having to update your own menu. For PI-IBS and any type of irritable bowel, ModifyHealth makes it easy.