IBS and SIBO are common and can interfere with quality of life. Symptoms include bloating, abdominal pain, and altered bowel function (constipation or diarrhea). As we are learning more about IBS and SIBO, we are learning that alterations in the intestines may be a cause. Excitingly, recent evidence suggests that certain dietary changes may help repair the intestines in those with IBS and SIBO. Let’s discuss.
Healing the Cause of IBS and SIBO
Dr. Michael Ruscio: Hi, this is Dr. Ruscio. Let’s discuss healing the cause of IBS and SIBO.
IBS, or irritable bowel syndrome, and SIBO have much overlap, and the symptoms can include things like bloating, abdominal pain, and altered bowel function, meaning either constipation or diarrhea, or perhaps a mixture of the two. It can be a very debilitating condition. Fortunately, as we’re learning more about the gut, we are learning some of the underlying changes that can occur in the intestines that can cause IBS and cause SIBO.
Excitingly, one diet in particular has been shown to have the ability to, at least in part, repair some of what may be the underlying changes in the intestines that causes IBS and/or SIBO.
The diet is the low FODMAP diet. And a low FODMAP diet essentially restricts forms of carbohydrates that encourage or feed bacteria. And these are sometimes seemingly healthy foods, like broccoli and asparagus. However, for some people, these foods can feed bacteria in the gut and that may be problematic, especially for people with IBS and SIBO, because the low-FODMAP diet does have an impressive number of clinical trials that have shown benefit.
But what happens in the intestines? One study in particular has shown the ability of a low FODMAP diet to increase serotonin cells in the intestines, and actually make the number of serotonin cells proximate, or become more like that of healthy controls.
Now, why is serotonin important? Well, for IBS, irritable bowel syndrome, serotonin can be important because serotonin is involved in what’s known as nociception or pain. So that pain signaling, or lack of serotonin, and its influence on pain may account for the abdominal pain that is reported in IBS. Or the bloating, because sometimes people report a bloating-type discomfort pain. And it also may account for slowed motility.
Serotonin in the gut is partially responsible for motility, or the ability of food to move through your intestinal tract at the appropriate pace. When this does not happen, you can have a condition known as small intestine bacterial overgrowth. Some of the medications that are used to prevent SIBO, small intestine bacterial overgrowth, from coming back once it’s been cleared are actually agents that help to facilitate the release and the function of serotonin in the gut. So, interesting that the low FODMAP diet has been shown, at least in one study, to have the ability to increase serotonin receptors.
Now, the study I’m referencing that showed this change in serotonin receptors occurred in the colon. It would be ideal if we had data showing that this change occurred in the small intestines, but it’s much harder to perform biopsies of the small intestine. I’m going to make an assumption—I think it’s a fairly safe one—that this would also occur, this increase in serotonin cells, would occur in the small intestine in addition to the colon.
Now, if you zoom way out, it’s not a large stretch to say that a diet that has been shown to be very helpful for those with IBS and with SIBO, namely the low FODMAP diet, would probably cause a repair or healthy changes in the intestines in the people who went on it, hence the increase in the serotonin cells in the gut. This is important because sometimes a low FODMAP diet is criticized, which I’m open to, but it’s criticized for potentially causing a decrease in bacteria in the gut.
And the data here are not all consistent. That hasn’t been conclusively shown. But it may be that for people with IBS, and certainly for people with SIBO, they need an approach that may dampen, or decrease, or trim the microbiota back.
So this is very exciting news. And it, I think, illustrates one important principle. That if something is working for you, if something has a good clinical outcome for you, then be confident in that. Because if you look at mechanisms, like for example bacteria counts may go down on a low FODMAP diet, and if you’ve been told that’s bad, it would be really unfortunate if you stopped using a diet that helped you— the low-FODMAP diet. Because at the same time, you may actually be repairing and allowing the growth of additional serotonin cells in your intestines, which are very important to help your intestines function properly.
So this is where you can get into the debate regarding mechanism. It’s why I always recommend that we look at clinical trials and outcome data to steer the recommendations that we make. So a low FODMAP diet for those with IBS and SIBO can be very helpful. Remember, you don’t have to be on a highly restrictive, low FODMAP diet in perpetuity. You start low, and then you try to broaden your diet to the broadest diet that you can tolerate. But remember, evidence is showing, at least according to this one preliminary study, which is very exciting in my opinion, that a low FODMAP diet can help heal and repair the intestines via a very interesting mechanism, which is that of allowing an increase in serotonin cells in the gut.
So this is Dr. Ruscio, and I hope this information helps you get healthy and get back to your life. Thanks.
What do you think? I would like to hear your thoughts or experience with this.
Dr. Ruscio is your leading functional and integrative doctor specializing in gut related disorders such as SIBO, leaky gut, Celiac, IBS and in thyroid disorders such as hypothyroid and hyperthyroid. For more information on how to become a patient, please contact our office. Serving the San Francisco bay area and distance patients via phone and Skype.