- Small intestinal bacterial overgrowth (SIBO) is a condition that causes gas, bloating, and diarrhea.
- The SIBO diet can help relieve symptoms by eliminating foods that digest more slowly in the gut.
- SIBO diets cut out whole grains, legumes, soft cheeses, and fiber-rich fruits or vegetables.
- Visit Insider’s Health Reference library for more advice.
Small intestinal bacterial overgrowth (SIBO) occurs when too much bacteria, usually coliforms, grow in the small intestine. Coliform bacteria ferment carbohydrates, which often lead to symptoms like excess gas, bloating, abdominal pain, and diarrhea.
The idea behind the SIBO diet is to maintain gut health by eating foods that are less likely to ferment in the intestine and feed coliform bacteria.
While SIBO is initially treated with antibiotics, “we think that the diet will prevent the bacteria from coming back,” says Mark Pimentel, MD, director of the Medically Associated Science and Technology program and associate professor of gastroenterology at Cedars-Sinai health organization.
There has been relatively little research conducted on the SIBO diet, but it has many overlaps with the low-FODMAP diet, which has more scientific backing as a treatment for gastrointestinal issues.
Here’s what you need to know about the risk of developing SIBO and how the SIBO diet can help.
Foods to avoid on the SIBO diet
While the low-FODMAP diet was originally designed to treat IBS, it is often prescribed to treat SIBO as well. Like the low-FODMAP diet, the SIBO diet aims to reduce foods that can ferment in your intestines — this means cutting out foods that normally digest more slowly like fiber and certain sugars like lactose.
The main difference between the SIBO diet and the low-FODMAP diet is the level of restriction, says Pimentel. For example, the low-FODMAP diet cuts out most fruits and some root vegetables like onions and garlic, while the SIBO diet is more lenient.
On the SIBO diet, you should not eat:
- Any kind of sugar alcohol — these are often found in “sugar-free” products and often end with “ol” like sorbitol
- Soft cheeses and milk
- Probiotic supplements and foods containing probiotics like yogurt
- Whole grain bread or oatmeal
- Beans or legumes, including whole or ground up, like in hummus
- Cruciferous vegetables like cabbage and leafy greens
- Apples, pears, and bananas should be eaten in limited amounts
Foods to eat on the SIBO diet
Foods that break down quickly into simple sugars are good for SIBO, because they give you nutrition without feeding the bacteria in your lower intestines. SIBO diet-friendly foods include:
- Any type of meat
- Hard cheeses and lactose-free milk
- White bread, pasta, cream of wheat
- Root vegetables like carrots and beets
- Fruit vegetables like peppers, tomatoes, cucumber, and squash
How effective is the SIBO diet?
Though there’s less published scientific evidence for the SIBO diet’s effectiveness compared to the low-FODMAP diet, Pimentel recommends that SIBO patients should choose the SIBO diet after taking
“The FODMAP diet is studied a lot more, but has some risks because of the restrictive nature,” Pimentel says, adding that staying on the low-FODMAP diet for more than 3 months can put you at risk for malnutrition.
Pimentel advises that people should not try to follow the diet on their own, and should always work with a doctor. While people with conditions like IBS or SIBO often feel better when eating highly-restrictive diets, they may harm their overall health in their effort to avoid symptoms. “Being under the guidance of a dietitian is the proper way to do it so that you don’t fall into the traps of the diets,” says Pimentel.
If one round of antibiotics and the SIBO diet don’t work to get rid of SIBO symptoms, you may need to do multiple courses of antibiotics, Pimentel says. If there is an underlying condition like
or an obstructed bowel causing SIBO, you may develop recurrent SIBO and you will need to treat the larger problem or regularly take courses of antibiotics.
Risk factors for developing SIBO
Many people assume that SIBO is caused by “bad bacteria” in the gut, but the issue is not the type of bacteria, but rather the amount.
It is normal to have a lot of bacteria in the colon, where digestion moves more slowly, but an overgrowth of bacteria in the small intestine causes problems like gas and bloating or more concerning symptoms, like diarrhea and constipation.
Here’s what can increase your risk of developing SIBO:
- Age. There isn’t enough research to determine how many young people have SIBO. However, among older adults, SIBO is fairly common – around 15% of older people have the condition. Older adults are more susceptible to SIBO because they are more likely to have slow digestion and to get gastrointestinal surgeries, which can disrupt the balance of gut bacteria.
- IBS and other diseases. There’s also a huge overlap in symptoms between irritable bowel syndrome (IBS) and SIBO and some estimates calculate that one-third of IBS patients have SIBO. You may be at greater risk of developing SIBO if you have a disease that slows digestion like Parkinson’s disease, hypothyroidism, or diabetes.
- Bowel obstruction. Having a bowel obstruction or deformity in your intestine caused by surgery can also put you at greater risk of developing SIBO.
- Proton-pump inhibitors. If you have a condition like acid reflux for which you take proton-pump inhibitors like omeprazole, this will decrease your levels of stomach acid. Stomach acid is important because it prevents an overgrowth of bacteria in the upper small intestine, so without it, you’re more likely to develop SIBO.
The SIBO diet may help relieve gas, bloating, and diarrhea caused by small bacteria intestine overgrowth. It requires cutting out whole grains, legumes, soft cheeses, and fiber-rich fruits or vegetables.
While there are promising results for low-fermentation diets treating gut diseases like IBS, there is no evidence yet proving this type of diet will have the same effect for SIBO. No matter what diet you choose to follow, make sure that you are always under the supervision of a medical provider.