This post is the first in a three-part series on Small Intestine Bacterial Overgrowth focusing on SIBO symptoms, root causes and testing. Stay tuned for Part 2 and 3 on SIBO natural treatments, herbal supplements and diet.
About a year ago, I started noticing some mysterious symptoms creeping back into my life.
Having been through half a decade of digestive woes, I didn’t pay much attention to the occasional bloating and constipation. Didn’t consider how my usual diet – full of healthy foods that, in theory, supported good gut health – was starting to make me feel off after meals. Didn’t even worry that my habitual burping, and more than occasional tooting, was becoming a regular companion soundtrack to our nighttime Netflix binges.
There was so much easy rationalizing. I was drinking more homemade kombucha, which was fizzy. I was going semi-horizontal after meals, which was bad for digestion, but could eventually be corrected. And I was getting more and more comfortable in my relationship, which meant maybe it didn’t matter if I just let ‘er rip.
It wasn’t until later in the year, once my book tour downgraded to a more manageable pace, that I was able to pay attention to my daily habits and see myself more clearly. And what I saw was a muffin top.
If you’re familiar with my Hashimoto’s story, you’ll know that vanity was the original straw that broke the camel’s back and forced me to take my symptoms more seriously. My skin was such a raging mess I would have tried anything, even a year of intense monthly lifestyle changes, to make it better.
Well, bikini season was a similar wake-up call.
Perhaps it’s a testament to how comfortable I am with my weight and body overall that it took so long to notice the inner tube that had lodged itself in my abdomen, giving me a permanent first trimester bump.
In yoga class, I had begun to note how my stomach would dip over the tops of my leggings no matter how many bow poses I did in a week. This is what people talk about when they all of a sudden realize they’re getting older, I commiserated to a friend. Even when I go to Pilates twice a week, my body just won’t hold the same tight shape. C’est la vie.
Eventually, though, my self-consciousness forced me to consider other causes. And once I started to put the physical pieces together—the outward with the inward–I decided to see a functional medicine doctor for a full workup. And the prognosis I received was not the onset of a deep case of “The Thirties,” but a diagnosis of SIBO: small intestine bacterial overgrowth.
What is SIBO?
Small intestine bacterial overgrowth is exactly what it sounds like. It’s a type of dysbiosis, which simply means an imbalance in the trillions of bacteria that dominate the gut. In the case of SIBO, however, the issue is not necessarily the imbalance between good, beneficial bacteria and bad, pathogenic bacteria (though that could be part of it). Rather, the main problem is location, not type.
Though critters colonize all sections of our alimentary canal, the majority of it is found in the large intestine (also known as the colon), where it assists in the final step of the digestive labyrinth and prepares for evacuation.
The small intestine, on the other hand, is where your food intermingles with digestive juices and nutrients are absorbed into the bloodstream. It’s not a place where bacteria belong or have a function. In fact, as is the case with SIBO, the presence of too many critters gets in the way of nutrient absorption and causes a host of other issues.
Since these are living organisms with their own palates and cravings, bacteria in your small intestines means there are other people at the dinner table competing for food and taking sustenance for themselves.
And when there’s not much nourishment to be had, they turn to the next best thing: you.
When unwanted bacteria begin feasting on your intestinal lining in the small intestines, the result is often leaky gut disease, an increased permeability of said lining. The byproduct of leaky gut disease, where larger food particles (instead of just essential nutrients) seep into the bloodstream, is often food sensitivities and autoimmunity.
Though you can have leaky gut, food sensitivities, and an autoimmune disease without SIBO, it is not unusual for it to be a root cause. For example, according to one study published in the American Journal of Gastroenterology, 66 percent of patients with celiac disease who maintained a gluten-free diet, and still had unfortunate symptoms, tested positive for small intestine bacterial overgrowth.
Some of these unfortunate symptoms that point specifically to SIBO include: bloating, gas, burping, reflux and other discomfort after meals. Constipation and diarrhea are common, though usually you only go down one of those lanes.
The reason for the distended belly is because of all the gases the bacteria release when they eat. Your small intestine was not designed to withstand the build-up, and the gases tend to get trapped, or released anyway they can through reflux and burping, or out the other end. You can also experience nausea from slowed stomach emptying due to the traffic jam.
If the miscellaneous gastro symptoms I just described sound like the usual description for IBS, you’re right. The problem with diagnoses of IBS—the most common gastro “syndrome” in the world—is that they are usually BS. It’s meant to be a diagnosis of exclusion, only reached when all other possibilities are ruled out. A collection of symptoms, not a root cause.
The majority of these sufferers are actually experiencing SIBO in disguise (or, staring right at you, so long as you know what to look for)–60 percent of all IBS cases are caused by SIBO!
Other symptoms to look for are a result of the absorption issue: being underweight and anemic. As a consequence of all the shared meals with your bacteria, nutrient deficiencies are common, especially with vitamin B12, decreased ferritin and increased folic acid.
Lastly, brain fog, depression and anxiety can occur as a result of the damaged cell wall affecting the brain. It’s not personality or stress alone. It’s a symptom of the gut’s circumstance.
Here’s a symptom cheat sheet:
- Abdominal bloating
- Gas: belching and flatulence
- Abdominal pain and cramps
- Constipation, Diarrhea, or both
- Acid Reflux
- Food Sensitivities
- Joint Pain
- Eczema, rosacea or rashes
- Anxiety and depression
- Malabsorption / nutrient deficiency
- Anemia (Iron or B12)
- Weight Loss
What Causes SIBO?
So if SIBO is an underlying cause of IBS, leaky gut, and autoimmune disease, what is the underlying cause of this bacterial overgrowth?
Diet certainly affects the balance of bacteria in our bodies. But one of our internal functions must go haywire in order for our bacteria to enter the small intestines and become trapped there.
Contrary to what some may think, the migration of bacteria from the colon doesn’t just happen. The small intestine is its own organ with a front and back door–completely separate chambers from the large intestine. Which means the problem must occur earlier on in the digestive process.
On the front end, the main culprit to explore is low stomach acid, usually a result of popping one too many Peptos, Prevacids or other Proton Pump Inhibitors in one’s lifetime.
Though certain drug companies have tried to convince you otherwise, your stomach acid is very necessary for maintaining gut health, preventing food poisoning, and generally, making sure that outside bacteria get killed before making their way into the small intestine.
But even if some unwanted bacteria get through that initial hurdle, our migrating motor complex (MMC) should ensure that it gets pushed down and out. This internal function also protects against back flow from the large intestine.
Which is why Dr. Allison Siebecker, who’s arguably one of the world’s leading experts on SIBO, believes that the root cause of SIBO centers around the malfunction of the MMC. The question, as she puts it, is why aren’t the bacteria being removed, not why are they there.
The Root Cause of the Root Cause: Why the MMC Goes Haywire
The Migrating Motor Complex only activates during a fasting state, between meals and overnight, and relies on your immune cells to kick it into gear.
The most common cause of low MMC function is food poisoning, also known as post-infectious IBS. When harmful bacteria enter the small intestine (often as a result of low stomach acid) they release a toxin that kills the immune cells that trigger your MMC.
Often times you’ll feel better from food poisoning a day or two later. The deeper symptoms related to the MMC may take months to arise, which is why doctors don’t always link it to SIBO.
The second cause is structural—a kinking of the intestines (blind loop syndrome), an impasse or strictures from abdominal surgeries (hernia, C-section, appendectomy, endometriosis, etc.), or other organs pressing on it.
Finally, another important cause: hypothyroidism can slow the migrating motor complex (!!). There’s still a little ambiguity regarding the connection, but several studies have chronicled the link between sibo and hypothyroidism. And the most common GI complaint among low functioning thyroid sufferers is constipation, a result of slowed motility.
It’s worth noting that most people experience constipation when the MMC is not functioning properly, but you can have poor motility in the small intestine and still experience diarrhea if there’s fast motility in the large intestine.
The good news is that SIBO only becomes chronic when the underlying cause is not addressed. The bad news is there is a high probability of relapse, especially when the underlying cause is not fixable. I will get into how to address some of these issues during part two of this series that focuses on treatment.
How Do You Test For SIBO?
The main SIBO test involves drinking a synthetic sugar solution and breathing into a tube at various intervals thereafter. It is fairly time consuming, but not unpleasant on the grand spectrum of gastrointestinal tests!
The test measures the levels of hydrogen and methane in your breath as the sugar solution makes its way through various parts of your intestines.
Carbs are your bacteria’s number one food source, and symptoms of bloating are caused by the gases they produce as they eat our food. Hydrogen and methane can only be produced by bacteria so their presence in your breath is a dead giveaway. The timing is what indicates whether it is in your small or large intestine. It usually takes two hours to progress to the latter.
The tests only vary in the type of sugar solution used: glucose or lactulose. There are pro’s and con’s to each, and some doctors after receiving a negative result, will try the other.
Glucose can only test the first two to three feet of the intestines, because after that it’s absorbed into the body. But you tend to get a better, clearer reaction from it, so long as the bacteria is actually in that area of the intestines. Lactulose is the safer bet if you want to test for bacteria beyond that point, where it is more likely to hang out.
One thing to note is that doctors and labs still lack a definitive consensus on what levels constitute a positive result. If you come up negative and doubt that diagnosis, it may be worth trying the other sugar (lactulose or glucose) or taking your results to another specialist for a second opinion.
If you treat your SIBO and still have symptoms but come up negative on the SIBO test, there’s likely another diagnosis at play. Most of the time we have more than one digestive problem. And if the connection between SIBO and other conditions is any indication, that is usually true of our whole health picture.
What Are My SIBO Treatment Options?
There are many options for treating SIBO, both through antibiotics, herbal supplementation and diet, or a combination of all three. It often varies for the individual case, and can take a few tries to hit on the right recipe.
The next post in this series will cover the many options out there for SIBO treatment, and the final installment will do a deep dive on how diet factors into getting rid of this pesky bacterial overgrowth and healing the gut.
Hopefully by then I will also have my latest results to share with you!
- Dr. Will Cole answered reader questions about SIBO on Facebook LIVE with me. Watch the interview here.
- Dr Allison Siebecker’s site is hub of amazing information, SIBOinfo.com
- Much of the above advice was gleaned from this course I took, SIBO Fundamentals, which is meant for practitioners, but I found really informative. It includes a lecture with Dr. Allison.
- Gut Health Protocol
- The New IBS Solution, which is out of date, but one of the pioneering books on SIBO.
Do you have questions about SIBO and how to treat it?
Not your first rodeo with this digestive disorder? Please share your experiences and queries in the comments section.
I will address them in future posts!