The Link Between Hydrogen Sulfide and Gut Issues (IBD/IBS) - Part 1

3 minute read

A topic I feel is relatively underappreciated in regards to gut health is hydrogen sulfide. Hydrogen sulfide is one of the gases that the bacteria in our gut can produce, and in this article I will explain how it relates to gut issues such as IBD and IBS. For me personally, understanding this topic has been a game-changer for my health when nothing else seemed to help. I believe it could be particularly helpful to people who haven’t responded well long-term to IBS treatments and people like me who didn’t do well on diets like SCD or GAPS used for IBD.

The Importance of Sulfur

Before looking at how sulfur relates to gut issues, it is crucial to understand what sulfur is and why it’s so important. Sulfur is the third most abundant mineral element in the body and comes in primarily through our diet. Lots of the healthiest foods are high in sulfur, such as garlic, onions, eggs and cruciferous vegetables. It is not sulfur itself that provides benefit to the body, but the sulfate that sulfur gets converted into. Sulfate is incredibly important for detoxification, building connective tissue, immune function and much more. Having enough sulfate around in the body is a top priority.

Bacterial Overgrowth

An issue arises if our body’s ability to convert sulfur into sulfate becomes impaired and we aren’t getting the necessary amount of sulfate that our body needs. You may be consuming a high sulfur diet, but if this sulfur cannot be converted efficiently into sulfate then it’s going to get “backed-up”. An idea that Dr Greg Nigh has put forward in his excellent book ‘Devil in the Garlic’ is that, as a workaround for impaired sulfur metabolism, our bodies will grow a type of bacteria in our gut called sulfur-reducing bacteria (SRB). These bacteria consume the sulfur we eat and produce hydrogen sulfide as a byproduct. Hydrogen sulfide is a substrate for sulfate production, meaning it is able to be converted into sulfate. It can be dispersed freely throughout the body to the mitochondria, where it can then be oxidised into the sulfate we desperately need. Whilst being a handy workaround, the downside is that too much hydrogen sulfide can cause nasty symptoms, many of which we associate with IBS. Some of the symptoms that might be experienced include digestive issues like diarrhea and constipation, brain fog, memory issues, fatigue and skin issues like redness.

Hydrogen Sulfide and Butyrate

Ulcerative colitis has been associated with an increased production of hydrogen sulfide in the gut1, indicating that it plays some sort of role in the disease. One of these roles I believe is its inhibition of butyrate metabolism2. Butyrate is so incredibly important for gut health. It provides the fuel for colonocytes, the cells that line our gut, allowing them to maintain the integrity of the gut lining. “Leaky Gut” occurs when this integrity is lost, which can cause even more problems as undigested food particles and toxins are “leaked-out” into the bloodstream. So not only do high levels of the Hydrogen Sulfide gas itself cause problems, the decrease in butyrate production as a result of this can lead to even more issues.


It is worth reflecting on the idea that whilst we may be dealing with such awful symptoms and health problems associated with excess hydrogen sulfide, it may be a side-effect of our bodies adapting to the environment. At the end of the day, survival is the body’s primary objective, so getting the sulfate it needs to survive is of primary importance. It also challenges the idea germs themselves cause disease, as it is not the SRB that are the root cause of these conditions, but rather our impaired sulfur metabolism and the resulting shift in our microbiome.

In part 2 I’ll be going over how sulfur metabolism can get messed up, leading to the overgrowth of SRB.