Anna Marija Helt, PhD & Aubrey Levitt
Let’s geek out on SIBO. What is SIBO? It doesn’t stand for small, irregular body output. Not quite. SIBO means small intestinal bacterial overgrowth. Now, if that isn’t any more clear, I will tell you what that means in just a moment. First, a little background on our gut bacteria….
We’ve evolved to get as much out of our food as possible. Nature likes zero waste! Even the stuff we don’t digest — fiber and complex starches for example — is digested by our resident gut bacteria. (Mostly those in the large intestine, which has a gazillion more bacteria than the small intestine.) Not to be left out, the microbes in the small intestine are important, too…they assist in nutrient absorption, influence metabolism of the intestinal lining, protect us from invading pathogenic microbes, encourage small intestine motility and even produce some nutrients for us. Not bad considering there aren’t so many of the little guys.
Back to SIBO. SIBO is usually when bacteria from the large intestine creep up into the small intestine where they don’t belong. Occasionally, SIBO is due to overgrowth of species normally present in the small intestine. They get a little carried away. Either way, and when this there is increased fermentation of starches and fiber in the small intestine, leading to uncomfortable side effects such as gas and bloating. On top of that, bacteria in your small intestine may munch on the bile you need for digestion and absorption of fat and fat-soluble vitamins, leading to deficiencies.
SIBO can also be an underlying cause of IBS, or, in turn, may result from IBS.
So, how do we wind up with too many bacteria in the small intestine?
Turns out there are lots of possible causes, and more than one may be at play if you’re unlucky:
- Insufficient digestive secretions – Stomach acid kills bacteria. Not enough acid means more bacteria reaching the small intestine. Digestive enzymes made by the stomach, pancreas and small intestine also inactivate bacteria, so lower enzyme levels may also allow excessive bacterial growth.
- Sluggish intestinal motility – Our intestines essentially squeeze food and digestive juices down the line via contractions of the intestinal walls. This also helps push bacteria from the small intestine downstream, while also keeping those from the large intestine from migrating upwards. But, even when there’s no food around, movements called “migrating motor complexes” (MMC) help keep the bacteria heading in the right direction….DOWN. Yes, that’s right. That gurgling you notice between meals may not mean you are hungry, but that your intestines are doing a little maintenance to clean themselves. Like running the vacuum, MMC are cleaning up leftovers and doing some scrub-a-dubbing. When this system is slowed down or interrupted, then bacteria will not be moved along as they normally are. Note that eating too often will interfere with MMC. Remember the MMC does its work when we are fasting. Also, an infection, like a case of food poisoning, can have lasting results on the MMC. And, when we get older, our MMC start to slow down on the job.
- Immune system irregularities – A fully operational immune system offers another line of defense to regulate unwanted bacteria growth. Just, a reminder, chronic stress can weaken the immune system. Anyone suffer from stress? Not me, of course. (Yeah, right.)
- A wimpy barrier between the small and large intestine – The ileocecal valve controls transit between the small and large intestines. It opens to let digested (or undigested, in some cases) food into the large intestine, while otherwise preventing bacteria from moving up the train track.
- Other structural issues in the intestine – For example, diverticulitis, where pockets form in the intestine. These make great (from a bacterial point of view) apartments for bacteria to fill up. Or the aftermath of intestinal surgery may be the problem.
- Diseases – Such as diabetes, Celiac disease, Crohn’s disease, liver disease and others.
How do you know you have SIBO?
It’s not so easy, as some of the symptoms may be due to any number of problems: Boating, discomfort, diarrhea, weight loss, and such. Testing for SIBO is difficult and often inaccurate. Samples from the small intestine are considered the gold standard, but these are pretty invasive by their nature…an endoscope or other instrument inserted via your mouth (fun!). This technique isn’t great if the bacteria are partying in a site the scope can’t access. There are breath tests that can be conducted by your doctor, which are way easier to do (and go through!). Though these don’t necessarily give the most reliable results, due to a lack of agreement on what different levels of the substances measured actually mean. But, breath tests are what most docs rely upon. The idea is that gases like hydrogen and methane that are produced by bacteria that normally live in the large intestine (and largely farted out) show up in the small intestine with SIBO and come out the other end.
Ways you can manage SIBO
SIBO is often stubborn and reoccurring. About 45% of cases return after any sort of treatment. As you can imagine, killing the bacteria often does not tackle to the root problem…usually the bacteria will overgrow again around 1-2 months later, if the reason they overgrew in the first place isn’t or can’t be addressed. This is why it is important to look at more holistic approaches when it comes to managing SIBO.
- Take prokinetic herbs – These are herbs or foods, like ginger, that stimulate normal contractions in the intestines (while also reducing painful spasms).
- Don’t snack between meals – The MMC comes through about every 90-120 minutes, assuming you’re not eating. It’s about a two-hour long process for this cleaning crew to get the job done. The process doesn’t work if you eat more frequently than this.
- Consider herbs to manage bacterial growth – In one study herbal remedies went head to head with the leading drug treatment for SIBO, rifaximin, and the herbs did slightly better. There isn’t much evidence, to our knowledge, of bacteria developing resistance to herbs, which are more complex, chemically-speaking, than drugs.
- Limit intake of sugar and refined carbs – Bacteria love these, so limiting them may help to mitigate symptoms when you have an overgrowth problem. Note that complex carbs are an important part of a balanced diet, so we don’t want to go carb-free long term.
- Manage your stress – Easier said than done 🙂
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