Searching online for diet plans can be extremely frustrating. It’s hard to know which eating plans are medically responsible, which ones are controversial but based on research or science, and which ones are simply fad diets.
More importantly, it’s hard to know which ones really work.
Just the names of many diets, loaded with initials or buzzwords, are so difficult to decipher that lots of people skip right over them.
The SIBO Diet is one of those somewhat-mysterious eating plans. You may have seen references to it but scrolled right past them, since it’s a lot easier to get your brain around a “low-carb diet” or even a “Paleo Diet” than it is to figure out what “SIBO” is supposed to mean.
You probably haven’t missed anything. The SIBO Diet isn’t designed for fast weight loss, and it’s not a plan for healthy eating which will gradually help you get into shape and lose weight. It’s strictly a medical diet – or more accurately, a broad-brush description of diets – which help people with the symptoms and pain caused by a serious issue in the digestive tract: Small Intestinal Bacterial Overgrowth (SIBO).
SIBO diets are extremely restrictive. One of them is so restrictive that even patients desperate to relieve their symptoms have so much trouble following it just throw up their hands and give up.
If you suffer from the often-excruciating pain of SIBO, however, the right diet can be a godsend.
Is SIBO a Real Disease?
Small Intestinal Bacterial Overgrowth isn’t actually a disease, but it’s definitely real. For years, many doctors pooh-pooed the entire concept of keeping gut bacteria (the “healthy” or “beneficial” bacteria, and the “harmful” or “bad” bacteria) in balance. More recently, SIBO was thought to be quite rare and not a major concern.
However, research has shown that SIBO is not only real, but a lot more common than had been believed or taught in medical school.  More than 28 studies have been done on the subject and show that as many as 78% of patients with IBS (irritable bowel syndrome) also have SIBO – and that the pain often diagnosed as IBS symptoms may really be caused by SIBO.  A number of other digestive disorders like Crohn’s disease and celiac disease have also been linked to SIBO.
In a nutshell, here’s how it works.
We all start with a relatively healthy balance of beneficial and harmful bacteria in our gastrointestinal tract. In fact, there are trillions of bacteria living in what’s known as the microbiota; among other things, they help the body process food, fight undesired infections, assist in powering the metabolism and protect the immune system. The proper balance between good and bad gut bacteria is what allows the body to function properly.
For one of several possible reasons, the small intestine (also called the small bowel, and is between the stomach and large intestine) may stop processing food fast enough. Excess food sitting in the intestine creates an environment conducive to the growth of harmful bacteria, they multiply quickly, and there aren’t enough beneficial bacteria to kill them all off. All of a sudden, the gut’s bacterial balance is thrown out of whack and you have a small intestinal bacterial overgrowth which can cause severe pain. It can also lead to other difficult problems like leaky gut and malabsorption of key nutrients.
What could lead to that intestinal issue? There are no specific underlying causes known, but a number of risk factors have been identified:
- Chronic diseases including lupus, diabetes and inflammatory bowel disease.
- An immune system weakened by problems like AIDS or a deficiency in immunoglobulin-A.
- Regular or frequent use of opioids, proton pump inhibitors (medications that control stomach acid), antibiotics – and sadly – some of the anti-spasmodic medications used to treat IBS.
- Diverticulosis, previous colon surgery, or scar tissue from previous surgeries.
- Being older and/or being female.
All of the mechanisms by which SIBO can develop aren’t completely understood just yet. But no matter what causes it, it can be horrendously painful.
Symptoms of SIBO
There are no symptoms that are specific to SIBO. In other words, nothing allows doctors to automatically and definitively diagnose the condition.
The noticeable problems that are caused by SIBO all affect the digestive system, and occur on a regular or periodic basis. They include:
- Abdominal pain (usually after eating)
- Gas, cramps and bloating
- Diarrhea or constipation
- Always feeling full
- Unexplainable weight loss
Those who already suffer from medical issues like IBS and Crohn’s have probably guessed that those diseases are what are causing their symptoms. That’s why a special test is necessary to diagnose SIBO: a lactulose breath test. (Some doctors prefer to diagnose based on symptoms and exams instead of the test – but the test is faster and more conclusive.) 
The test is easy to complete (although you will likely have to modify your diet, medication and supplement regime before the test). You drink a beverage that’s filled with the sugar lactulose, and every 15 minutes you have to breathe into a balloon. Each time, the air is tested to determine if it contains excess methane or hydrogen. If so, that indicates SIBO – and treatment is the next step.
Hydrogen-prevalent SIBO (diagnosed, obviously, if hydrogen levels in the patient’s breath are high) is treated with the antibiotic rifaximin, sometimes also used to treat IBS. Methane-prevalent SIBO is more stubborn so it’s treated with two antibiotics, rifaximin and neomycin. The antibiotics are meant to kill the overgrowth of bad bacteria, relieving much of the pain that sufferers experience.
Rifaximin isn’t actually federally approved for the treatment of SIBO, and it’s very expensive. So some doctors try other antibiotics in its place, such as ciprofloxacin or metronidazole.
There’s another key element of treatment, though: permanently restoring the balance of good and bacteria in the gut. The use of anti-microbial herbs is one approach that doctors take, but whether or not herbs are suggested, patients will also be directed to make dietary changes. That means following a SIBO-friendly diet.
Most patients dealing with any medical condition are given recommendations and suggestions rather than a rigorous diet to follow. SIBO patients are no different.
In cases which aren’t too severe, minor dietary adjustments may do the trick. A nutritious and balanced diet, consumed in small and more frequent meals, will sometimes be enough to prevent food from building up in the small intestine. Probiotics may also help restore gut health and lessen the possibility of another SIBO incident.
If SIBO symptoms have become serious enough for patients to seek treatment, though, a more rigorous and restrictive dietary approach is often needed. The two diets which are usually suggested are a low-FODMAP diet and an elemental diet. The elemental diet is still relatively controversial and quite difficult to endure, so we’ll look at the more-universal low-FODMAP diet first.
What In the World is Low-FODMAP?
If SIBO wasn’t bad enough to understand, now we have FODMAP. It stands for the types of carbs which are difficult for the small intestine to absorb: fermentable oligosaccharides, disaccharides, monosaccharides and polyols. (See? SIBO wasn’t that hard, in comparison.) And the low-FODMAP diet is viewed by most experts as the best diet for SIBO patients.
Since that probably didn’t clear things up for you very much, here’s a more specific rundown of the FODMAPs.
- Fermentable carbohydrates: This simply means that the carbs are so difficult to break down that the bacteria trying to do it produce lots of gas.
- Oligosaccharides: These foods contain high amounts of the type of sugar typically found in rye and wheat, garlic and onions, and beans and legumes.
- Disaccharides: These are most often the lactose contained in milk and other dairy products.
- Monosaccharides: The most common one is fructose, found in many vegetables and used in artificial sweeteners like high-fructose corn syrup.
- Polyols: Naturally found in fruits like plums and peaches, and vegetables like cauliflower and mushrooms, they’re the sugar alcohols that are also added to sugar-free foods in the form of sweeteners like xylitol and sorbitol.
That’s probably a little more help, but it still doesn’t really tell you which specific foods you can and can’t eat. Here’s a general do-and-don’t list, but it’s not exhaustive; a doctor, dietician or nutritionist can (and should) give you more specific direction. They can also advise you on nutritional supplements and vitamins which may be needed, since many foods needed on a balanced diet are forbidden by the low-FODMAP protocols.
Here’s a sample of low-FODMAP foods that you can eat on this diet.
- Vegetables include lettuce and leafy greens tomato, green beans, lentils, broccoli, eggplant, carrots, some starchy vegetables like potatoes, and some squashes and zucchini
- Fruits include strawberries, cantaloupe, pumpkin, blueberries, grapes and kiwi
- Dairy (or “dairy”) options include hard cheese, feta cheese, almond and soy milk
- Proteins are basically limited to eggs, tofu and seafood (although some FODMAP diets also allow meat)
- A few grains or grain substitutes like quinoa, vegetable or corn pasta, some types of gluten-free bread, gluten-free crackers or gluten-free cereal, rice and gluten-free noodles
- Nuts and seeds including peanuts, sunflower seeds, macadamia nuts and peanuts
- Sweeteners like table sugar, maple syrup and dark chocolate (!)
So that’s the general list of foods that are OK, and many of them have the added benefit of containing prebiotic properties that help restore gut balance.
Now, swallow hard – here are the high-FODMAP foods you can’t eat.
- Vegetables including mushrooms, cauliflower, peas, asparagus, Jerusalem artichokes, onions and garlic, butternut squash, and beans and most other legumes
- Fruit like apples, peaches, watermelon, cherries, peaches, plums and dried fruit
- Most dairy including milk, flavored yogurt and ice cream
- Smoked, cured and many processed proteins (some FODMAP diets prohibit all meat and poultry)
- Most breads, cereals and snack foods, particularly those containing wheat, rye and barley
- Some nuts and seeds like pistachios and cashews
- Sweeteners or sweetened foods containing high-fructose corn syrup, honey and agave nectar, and all sugar-free foods
If you try this diet without the assistance of a health professional, one good source of information is the database created by Australia’s Monash University, a leading research department on FODMAP.  They have an easy-to-use app that can be invaluable.
There’s some good news about the FODMAP diet: it’s not intended for long-term use. You follow the complete eating plan for anywhere from two weeks to two months (depending on the severity of your symptoms).
After that, you gradually start reintroducing foods, keeping a diary of which ones cause problems and which seem to be fine. Over time, you create your own personalized and less-restrictive low-FODMAP diet that can permanently eliminate or reduce the pain and suffering caused by SIBO.
Another version of a SIBO diet, created by Dr. Allison Siebecker, combines the low-FODMAP approach with the completely grain-free Specific Carbohydrate diet (SCD), and is even more restrictive. The same goes for the Gut and Psychology Syndrome diet (GAPS), an elimination diet which lasts for weeks. That one revolves around cooked homemade food without most carbs and is also quite arduous. For that reason most doctors don’t suggest these diets, but they might help with difficult cases.
The Diet That’s “Elementary”
Some doctors prefer that their SIBO patients follow what’s called an elemental diet, which is administered in liquid form for several weeks – with no solid foods allowed.
The elemental diet contains essential nutrients that are in as close to their natural form as possible, blended into a liquid that’s either drunk or given through a feeding tube. It can restore bacteria balance in the microbiota, very quickly in many cases. However, studies show that about one-quarter of the patients given an elemental diet are unwilling to actually stay on it for as long as 2-3 weeks, because it’s so difficult to deal with.  Additionally five percent find the taste of the liquid unpalatable, although there are good-tasting options now available.
For that reason, many doctors don’t even suggest an elemental diet except in very serious cases. Chances are that if you’re suffering from SIBO, you’ll be given a low-FODMAP diet to follow, and it should definitely help.