Eating with Gut Problems (Part 2) - the low FODMAP diet

The picture

One of the most common reasons patients see me in practice is for their digestive issues. If you are reading this, you may be part of the 20% of the population that suffers from irritable bowel syndrome (IBS) [1].

IBS is highly heterogenous, meaning that it is difficult to map similarities in patients with this condition [2]. They all present differently. Some have food sensitivities with carbohydrates, others with fat, some have diarrhea, others are constipated, and others have alternating stool patterns.

This is why it is so important to take an individualized approach when treating this condition, and also to run the right labs such as the Hydrogen and Methane Breath Test.

So you have gut problems... but have you heard of SIBO?

A percentage of patients diagnosed with IBS may test positive for small intestinal bacterial overgrowth (SIBO), although it isn’t as high as we once thought [3]. SIBO, as its name implies, is an abnormal overgrowth of bacteria in the small intestine. It occurs when bacteria that normally live in the large intestine inappropriately migrate to the small intestine, causing numerous health issues.

These bacteria like carbohydrates, and consequently release lots of gas in the bowels which results in bloating/distention, abdominal pain, and a change in osmotic pressure. This change in pressure leads to an influx of fluid (water) in the bowel and the end result may be:

• Diarrhea

• Loose stools

• Constipation with loose stool

• Potentially other adverse gastrointestinal symptoms like acid reflux

• Extra-intestinal issues like joint pain, difficulty concentrating, rosacea, acne, etc.

Sounds similar to IBS, right?

Diet is the foundational intervention for IBS and SIBO

A diet that has been studied for its positive outcomes in IBS and SIBO is the low-FODMAP diet [4].

FODMAP stands for fermentable oligosaccharides, disaccharides, monosaccharides, and polyols. These are short-chain carbohydrates that easily ferment in the guts of susceptible individuals (i.e., those with IBS or SIBO), causing excessive gas, bloating, and many other symptoms such as those listed above.

Foods are either categorized as FODMAP friendly or unfriendly. Below is a snapshot of a list of approved and restricted foods retrieved from Stanford Hospital and Clinics (click for the full list) [5].

The premise of the diet is to eat low FODMAP foods in order to reduce/eliminate pain, gas production, and also to promote peristalsis of the gut (i.e., remain regular with normal stool consistency). 

Like I mentioned earlier, some foods will trigger certain individuals, but not others. Apples, for example, tend to set off gas and bloating in many. Further, gluten and dairy elimination has shown some relief for IBS individuals in clinical studies, but some are sensitive to just the lactose in dairy, whereas others are sensitive to multiple dairy components, namely lactose, casein, and whey.

A low-FODMAP diet can help normalize the osmotic pressure in the large intestine, and thus help reduce chronic diarrhea. But what about those who are constipated? For constipation, a low-FODMAP diet in combination with non-fermentable fibre and/or soluble fibre may be more helpful in promoting regularity.

When carbohydrates are not the only issue ...

An overgrowth of bacteria in the small bowel can impact fat absorption, too. Normally, fat is completed absorbed in the small intestine. However, an overgrowth of bacteria can deconjugate bile acids - which means bile can't do its job of absorbing fat.

These bacteria also "steal" nutrients by capturing and metabolizing them before they can be absorbed by the small intestine [6]. So, we end up seeing people with classic SIBO symptoms also present with greasy, floating stools, and nutrient/vitamin deficiencies. 

Clinical outcomes of a low FODMAP diet in IBS populations

Much like chronic conditions in general, the low-FODMAP diet does not fix the issue - it simply reduces symptoms. But, it can greatly improve the quality of life for sufferers, which at the end of the day, can mean everything.

Research has also found that the low FODMAP diet can positively influence serotonin cells in the digestive tract. Ever wondered whether there is a link between your digestive issues and depression? Read below... 

It is estimated that 90% of the body's serotonin is made in the digestive tract [7]. And we also know that abnormalities in serotonin re-uptake have been found in IBS population[8].

So, here is the most fascinating part about the low-FODMAP diet; preliminary research suggests a low-FODMAP diet in IBS patients positively changes the density of serotonin cells in their gut [9] .This change in serotonin could partly explain the mechanism of reduced abdominal pain and improved peristalsis/motility experienced by people following the low-FODMAP diet, since it is serotonin's role to dampen pain signalling and modulate motility of food moving through the digestive tract. 

While this diet isn't a long-term solution, it is certainly a step in the right direction toward feeling better!

Dr. Dominique Vanier is a registered naturopath in Burlington with a clinical focus on digestion and women’s hormones. Naturopath Burlington. This article is for information purposes only. It is not intended to treat or diagnose any health conditions.

References

1. Saha L. Irritable bowel syndrome: Pathogenesis, diagnosis, treatment, and evidence-based medicine. World J Gastroenterol. 2014;20(22):6759. doi:10.3748/wjg.v20.i22.6759.

2. Sood R, Gracie D, Law G, Ford A. Systematic review with meta-analysis: the accuracy of diagnosing irritable bowel syndrome with symptoms, biomarkers and/or psychological markers. Aliment Pharmacol Ther. 2015;42(5):491-503. doi:10.1111/apt.13283.

3. Ghoshal U. Irritable bowel syndrome and small intestinal bacterial overgrowth: Meaningful association or unnecessary hype. World J Gastroenterol. 2014;20(10):2482. doi:10.3748/wjg.v20.i10.2482.

4. Ghoshal U, Shukla R, Ghoshal U. Small Intestinal Bacterial Overgrowth and Irritable Bowel Syndrome: A Bridge between Functional Organic Dichotomy. Gut Liver. 2017;11(2):196-208. doi:10.5009/gnl16126.

5. The Low FODMAP Diet (FODMAP=Fermentable Oligo-Di-Monosaccharides And Polyols). Stanford, California: Stanford University Medical Center; 2012. Available at: http://fodmapliving.com/wp-content/uploads/2013/02/Stanford-University-Low-FODMAP-Diet-Handout.pdf. Accessed February 19, 2018.

6. Fan X, Sellin J. Review article: small intestinal bacterial overgrowth, bile acid malabsorption and gluten intolerance as possible causes of chronic watery diarrhoea. Aliment Pharmacol Ther. 2009;29(10):1069-1077. doi:10.1111/j.1365-2036.2009.03970.x.

7. Yano J, Yu K, Donaldson G et al. Indigenous Bacteria from the Gut Microbiota Regulate Host Serotonin Biosynthesis. Cell. 2015;161(2):264-276. doi:10.1016/j.cell.2015.02.047.

8. Padhy S, Sahoo S, Mahajan S, Sinha S. Irritable bowel syndrome: Is it "irritable brain" or "irritable bowel"?. J Neurosci Rural Pract. 2015;6(4):568. doi:10.4103/0976-3147.169802.

9. Mazzawi T, El-Salhy M. Effect of diet and individual dietary guidance on gastrointestinal endocrine cells in patients with irritable bowel syndrome (Review). Int J Mol Med. 2017;40(4):943-952. doi:10.3892/ijmm.2017.3096.