What’s Good For A Healthy Gut May Not Work For IBS

If you are suffering from irritable bowel syndrome (IBS), you’ve probably looked into different probiotics, prebiotics, and dietary fibres with mixed or even inconclusive results. From my clinical and personal experience with IBS, I have found that multistrain probiotic supplements, fermented foods like kefir and kimchi, and dietary soluble fibre (oats, chickpeas, whole grains, etc.) either have no effect, or they actually worsen symptoms! Why is it that these healthy things don’t work for IBS?

How Is IBS Different?

All IBS sufferers have a few things in common based on how IBS works. IBS is considered a chronic condition of the small intestine. It manifests as a disruption of the healthy gut bacteria populations (aka dysbiosis) and intestinal lining (aka leaky gut), which stem from a motility problem, leading to bloating, pain, and bad bowel movements.

Although IBS is generally not considered an inflammatory condition, it is characterized by an overactive immune system. This is why many IBS patients end up with multiple food sensitivities and non-celiac gluten sensitivity (NCGS). Many of these symptoms are primarily mediated by an immune system molecule called histamine. Fermented foods tend to be very high in histamine and natural probiotics, so frequently consuming them can add to the histamine and immune burden of IBS.

The beneficial effects of probiotics and fibre are not the same for IBS sufferers as in healthy individuals. The healthy intestine will react positively to a molecule called butyrate. Butyrate is a short chain fatty acid (SCFA) produced when the good bacteria eat your food, usually soluble fibres and short chain carbohydrates (from starchy foods). This process is called fermentation. In a healthy individual, butyrate and a high microbiome diversity are associated with many positive health benefits including healthy weight, improved cardiovascular outcomes, better mood, less allergies, and more.

But in IBS, the process of fermentation is generally a bad thing. What the healthy intestine does with butyrate is completely different from what happens in the dysfunctional intestine. In IBS, any kind of fermentation is potentially inflammatory, and extra butyrate can actually hinder intestinal healing. In diarrhea IBS, there is always extra butyrate kicking around in the small intestine, which in turn alters the colonic microbiome when it gets in, perhaps by feeding other bacterial groups that aren't meant to be fed. Many species in a multistrain probiotic are also known to increase butyrate production. This explains why IBS-D patients sometimes feel terrible when consuming soluble fibre and multistrain probiotics.

So What Works?

The best outcomes for IBS result from decreasing fermentation (and probably butyrate production), as the decrease of bacterial species that produce butyrate seems to be an adaptive response in IBS.

Reducing the fermentation of soluble fibre and short-chain carbohydrates either by decreasing their consumption in your diet, or by directly decreasing the overgrown bacteria, is the most reliable way of reducing IBS symptoms and healing the gut. Some patients find good relief from herbal antimicrobial treatments, antibiotics, and pro-motility drugs or supplements (prokinetics), along with a low FODMAP low starch diet.

Lifestyle modifications such as not eating late, eating smaller meals, not overfilling, managing stress, and periodic fasting are very useful tools in decreasing IBS symptoms. A small subset of IBS cases also results from a diminished serotonin synthesis or utilization, so looking into pharmaceutical support if you have severe mood issues alongside your IBS could be helpful as well.

There are also single strain probiotics that generally do not worsen IBS symptoms and show benefits more often compared to multistrain products, including Lactobacillus reuteri, Lactobacillus rhamnosus, Saccharomyces boulardii, and Bifidobacterium longum. These strains have a place in IBS treatment. Look out for future blogs discussing these probiotic strains in more detail.

A Final Word

We’ve just thrown a lot of information your way, so to sum up, IBS often stems from a chronic motility problem of a dysfunctional intestine. This then leads to dysbiosis or overgrowth, leaky gut, and food sensitivities. The keynote symptoms are bloating after meals, abdominal pain, and altered stool quality which usually result from increased immune activity and out-of-control gas production by the dysbiotic microbiome. While probiotics, fermented foods, and dietary fibre can be extremely beneficial for healthy individuals, they can increase immune reactivity and gas production in IBS, and we need to be cautious with their use.

Looking For More Digestive Support?

If you’re ready to learn more about how Naturopathic Medicine can support IBS, SIBO, and other gut disturbances, you can check out our resource pages here.