Is IBS Genetic? What the Research Tells Us

Irritable bowel syndrome (IBS) affects up to 20% of people in the Western world.

Scientists have long been baffled as to its etiology, but researchers have found a genetic defect that they believe makes some people more vulnerable to poor bowel function.

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The Genetic Link

Irritable bowel syndrome is a complex condition with no known cure. It causes a reduced quality of life due to its debilitating symptoms, repercussions on health, and impact on finances.

Poor diet and stress are two of the biggest factors contributing to irritable bowel syndrome; however, through genetic research other causative pathways have been discovered. (Henström & D'Amato, 2016)

Researchers have found that patients with a particular subset of IBS typically have a genetic defect that could be a key factor in the onset of irritable bowel syndrome.

This genetic defect is a mutation of the SCN5A gene, which affects the Nav1.5 channel, causing issues with bowel function. (Beyder, Mazzone, Strege, et al., 2014)

The Nav1.5 is a sodium channel in the gastrointestinal smooth muscle and pacemaker cells. Sodium channels provide regulatory functions. When the sodium channel is impacted it can send signals within the gastrointestinal smooth muscle and pacemaker cells.

This triggers the muscle and cells remain in constant action, causing gastrointestinal disturbances. (Sanders, Kito, Hwang, & Ward, 2016)

In one study, the sodium channel of 584 people with IBS was observed against 1,380 control subjects. The defect of the SCN5A gene was found in 2.2 percent of the IBS patients.

Later, these results were re-confirmed by researchers from the Karolinska Institutet in Sweden, and others in Italy and Greece in a genome-wide association study. (Beyder, Mazzone, Strege, et al., 2014)

Though this research is still in the early stages, it has given researchers the potential to find new ways of addressing gastrointestinal disorders. Until now, gastrointestinal disorders have been treated based on symptoms. This study may open doors to finding an effective long-term treatment of IBS.

For example, researchers used a drug called mexiletine to help a patient — with a defective SCN5A — treat symptoms of constipation-predominant IBS . Mexiletine reversed the patient's symptoms, which included constipation and abdominal pain.

What This Means for You

This means that in the near future if you have the defect of the SCN5A gene, more treatment options are likely to be available. For now, if you are at risk of IBS or have IBS symptoms, it is good to evaluate other potential factors which could have contributed to the onset of your IBS.

Family history is one risk factor. If you have a family history of IBS, you likely have a genetic predisposition to IBS, as well. (Saito, 2008)

Below are additional risk factors of IBS

• Being female — An increased risk of IBS in women was evaluated in a study in which researchers discovered a genome-wide significant association on chromosome 9q31.2 as well as the role sex hormones play in the onset of IBS. (Bonfiglio, Zheng, Garcia-Etxebarria, Hadizadeh, Bujanda, Bresso, et al., 2018)
• Age — People from their teens to '40s have a higher risk of developing IBS.
• A high-stress lifestyle — The stress hormone cortisol has been linked to a higher risk of IBS. (Sugaya, Izawa, Saito, Shirotsuki, Nomura, & Shimada, 2015)
• Suffer from mental illness — Psychological trauma or mental illness is linked to an increased risk of IBS. (Qin, Cheng, Tang, & Bian, 2014)  
• Food sensitivities — Food intolerances are reported in 70% of those with IBS . Two-thirds of those with diagnosed IBS avoid trigger foods to obtain relief from symptoms. (Monsbakken, Vandvik, & Farup, 2006)
• Taking medications — Several studies have linked antibiotic use and drugs containing sorbitol to IBS. (Distrutti, Monaldi, Ricci, & Fiorucci, 2016)
  

Symptoms of IBS to be aware of

• Abdominal pain and cramping
• Gas
• Diarrhea
• Constipation
• Food Intolerance
• Bloating
• Weight loss
• Nausea
• Fatigue

Ways to Find Relief  

Though there is not yet a cure or effective long-term treatment for IBS, you still have options. Several ways to find relief from IBS symptoms include:

• Behavioral therapy — This is a great way to get relief from IBS that is aggravated or developed as a result of mental illness.
• Effective stress management — This is key to lowering cortisol levels and alleviating stress-related IBS symptoms. Some ways accomplish this is through yoga, meditation, taking a bath, or running.
• Avoiding trigger foods — Foods such as dairy, caffeine, spicy foods, fatty foods, and alcohol are all culprits in triggering IBS symptoms. Avoid these foods for longer lasting relief.
• Eating more fiber — Eating foods high in fiber can help with constipation-related IBS.
• Herbal medicines — Can be very effective at alleviating IBS symptoms. For example, peppermint oil is excellent for spasms; chamomile relaxes sphincters, which reduce gas; and other herbs are effective laxatives if constipation is present.
• Taking a daily probiotic — Because antibiotics can cause gastrointestinal distress by killing off good bacteria, it helps to replenish the gut with good gut bacteria. Probiotics should be chosen specifically with a strain that has solid evidence for addressing particular aspects of IBS.
  
  For example, these strains are effective for bloating: Lactobacillus plantarum 299v (Jarrow Ideal Bowel Support), Lactobacillus rhamnosus GG (Culturelle), Bifidobacterium lactis HN019 (Xymogen ProbioMax).
  
  For constipation: Bifidobacterium lactis HN019 (Xymogen ProbioMax) reduces transit time,  Lactobacillus reuteri DSM 17938 (BioGaia Protectis) is effective for when methane levels are elevated, and Bifidobacterium Bb12 (TruBiotics) is effective as well.
  

Treatment is best done under supervision with a qualified healthcare practitioner.

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