Low FODMAPs Diet For SIBO – Is It Worth It?

FODMAPs (fermentable oligo-, di-, mono-saccharides, and polyols) are difficult to digest or poorly absorbed sugars. In searching for an elimination diet to treat hives in the 1970‘s, Australian researchers created the beginnings of the low FODMAPs diet. In 2005 the diet was introduced as a diagnostic tool for irritable bowel syndrome (IBS) – if a patient felt better when eliminating FODMAPs from the diet, they most likely had IBS. The low FODMAPs diet has become the most commonly prescribed dietary intervention to treat IBS, and now SIBO – but this doesn‘t necessarily mean it‘s the most successful. 

Why Low FODMAPs? 

The poorly absorbed sugars highlighted in the low FODMAPs diet can play a role in IBS (and SIBO) symptoms. The hallmark of IBS is visceral hypersensitivity when the GI tract is distended or enlarged – which occurs when anything (food, water, and/or air) is introduced into the gut. Visceral hypersensitivity simply means that people with IBS feel gut distention at a much lower volume than those without the condition. When fermentable foods – foods that increase gut distention because of gas production by gut bacteria – are taken out of the diet, it makes sense that people with IBS and SIBO feel better (less gas production = less distention), but it doesn‘t makethem better.

Why NOT Low FODMAPs? 

For SIBO and other functional GI disorders (gut disorders characterized by persistent, ongoing GI symptoms) we need to look at the big picture: Eating in a way that restores balance to the gut microbiome can lead to long-term improvement in symptoms. The best way to do this is to eat fermentable foods that promote the growth of beneficial gut bacteria. When looking at IBS patients on a low FODMAPs diet, breath testing improves but microbial analysis does not. No increase in health-promoting short-chain fatty acids (SCFAs) is observed because the diet actuallydecreasesthe food substrates for SCFA production. 

While removing fermentable foods from the diet can temporarily improve your gas and bloating, it does’nt address the root cause behind SIBO (or IBS for that matter). While you may feel better in the short term because of the reduction in gut distention, in the long term your problem remains unsolved. Remember, the low FODMAPs diet was initially used in the gut as a diagnostic diet for IBS, not a therapeutic diet.

Conclusion 

In my office I get to be Santa Claus when a patient who has been following a low FODMAPs diet comes to me very unhappy about being on such a restrictive diet. I love being able to tell them to reintroduce all those delicious and important fibrous and fermentable foods. While symptoms of gas and bloating may increase in the beginning, in the long term, you’ll be on your way to solving your SIBO and improving your gut as well as overall health.

For more information on Dr. Chutkan’s recommended diet for microbial imbalance, check out her book The Microbiome Solution (Penguin 2015) for a step-by-step guide.