SIBO Diet: What to Eat, What to Avoid, and What the Evidence Shows

Last reviewed 25 September 2026 · 17 sources, all checked on PubMed · For adults with a breath-test diagnosis of SIBO or IMO

Once you have a SIBO diagnosis, the first question is usually what to eat. The honest answer surprises most people: no diet has been proven to cure small intestinal bacterial overgrowth on its own. Diet still matters. It can ease bloating and pain while treatment works, one medical diet clears a positive breath test in most people who complete it, and how you eat afterwards affects whether symptoms come back. This guide separates what the trials show from what the internet repeats.

The short answer

  • There is no proven “SIBO diet”. Reviews conclude that the evidence is too weak to back any single diet as a SIBO treatment [12] [11].
  • Treatment is usually an antibiotic. Rifaximin clears SIBO on a repeat breath test in about 7 of 10 people [5].
  • For symptoms, a short low-FODMAP phase has the most evidence, mainly from IBS trials, where it is the best-studied diet [7] [8].
  • A two-week exclusive elemental diet normalised breath tests in 73–85% of people in uncontrolled studies [3] [4]. It needs medical supervision.
  • Keep restriction temporary. Long-term low-FODMAP eating may also starve the gut bacteria you want to keep [11].

What SIBO is, and why you cannot simply “starve” it

SIBO means an excess of bacteria in the small intestine that causes symptoms, most often bloating, abdominal pain, diarrhoea and excess gas [1] [2]. It is usually diagnosed with a glucose or lactulose breath test. Under the North American consensus, a rise in hydrogen of at least 20 parts per million within 90 minutes counts as positive, and a methane level of 10 ppm or more counts as methane-positive [6]. Methane-producing microbes are now described as intestinal methanogen overgrowth (IMO), and breath testing is used to investigate methane-associated constipation [4] [6].

The popular idea is that cutting carbohydrates starves the bacteria. Diet does change what those microbes ferment, which is why the right foods can reduce gas and bloating. But overgrowth usually has a cause, such as slowed gut movement, previous abdominal surgery or another underlying condition. The American Gastroenterological Association advises that management should focus on identifying and correcting that cause, fixing nutritional deficiencies, and antibiotics [2]. Food alone rarely fixes the underlying problem.

The evidence, diet by diet

Here is how the main approaches compare. “Breath-test normalisation” means a repeat test came back negative. That is useful, but it is not the same as lasting symptom relief.

Approach What it involves Best human evidence Our read
Low-FODMAP diet Cut quickly fermented carbohydrates for 2–6 weeks, then reintroduce them one group at a time Ranked first among IBS diets in an earlier network meta-analysis (13 trials, 944 patients) and has the most trials of any IBS diet in a 2025 network meta-analysis (24 of 28 trials) [7] [8]. In a 2025 IBS trial it cleared SIBO in 50% of the SIBO-positive patients, against 64% with rifaximin, in a small subgroup [9]. Best-supported option for symptoms. Not proven to clear SIBO.
Exclusive elemental diet Nothing but a pre-digested liquid formula for 14 days 80% had a normal breath test at day 15 and 85% by day 21 (93 people, retrospective) [3]. With a more palatable formula, 73% normalised and 83% reported adequate symptom relief (30 people, no control group) [4]. Strongest effect on breath tests. Hard to follow. Use only under supervision.
Soluble fibre (PHGG) with rifaximin 5 g a day of partially hydrolysed guar gum alongside the antibiotic Eradication 85–87% with the fibre against 62% with rifaximin alone (randomised, 77 patients) [10]. Promising add-on. One trial only.
Probiotics Various strains, usually alongside other treatment Meta-analysis: 62.8% decontamination rate, better than no probiotic (RR 1.61), but no protection against developing SIBO [13]. In a 179-patient trial, adding herbs, probiotics and prebiotics to antibiotics plus low-FODMAP did not change breath-test gas levels, although remission was higher, mainly in methane-type SIBO [14]. Possible add-on. Low-quality evidence.
SCD, bi-phasic and other “SIBO-specific” diets Expert-designed variations of carbohydrate restriction We found no controlled trials of these diets in people with SIBO. Unproven. No better supported than low-FODMAP.

One newer option is worth knowing about. In the 2025 network meta-analysis of IBS diets, a starch- and sucrose-reduced diet ranked first for overall symptoms. It rests on only two trials, however, and none in SIBO [8].

What to eat on a SIBO diet

Because the low-FODMAP method has the best evidence for symptom relief, a practical SIBO diet looks like its first phase. The aim is to lower the load of carbohydrates that gut microbes ferment quickly without dropping whole food groups.

Food group Lower in FODMAPs (normal portions) Higher in FODMAPs (limit during elimination)
Protein Eggs, fish, chicken, beef, firm tofu, tempeh Large portions of beans, lentils and chickpeas
Grains and starches Rice, quinoa, potatoes, oats in moderate portions, sourdough spelt bread Large portions of wheat and rye bread or pasta; added inulin or chicory root fibre
Vegetables Carrots, courgette (zucchini), spinach, cucumber, tomatoes, green beans, aubergine (eggplant), red peppers Onion, garlic, leeks (white part), cauliflower, mushrooms, asparagus
Fruit Kiwifruit, oranges, strawberries, grapes, blueberries in moderate portions Apples, pears, mango, watermelon, cherries, stone fruit, dried fruit
Dairy Lactose-free milk and yoghurt, hard cheeses such as cheddar and parmesan Regular milk, fresh soft cheeses such as ricotta and cottage cheese, ice cream
Flavour and sweeteners Garlic-infused oil, chives, green tops of spring onions, herbs, spices Honey, agave, high-fructose corn syrup, “sugar-free” products with sorbitol, mannitol or xylitol

Portion size matters. Many foods are low in FODMAPs only in small servings. A dietitian trained in the method, or an app with laboratory-tested portion sizes, makes the elimination phase far easier. Completion is the hard part. In a 2026 survey of people with IBS, SIBO or IMO, fewer than half finished the diet, and those who completed both phases were about 3.5 times more likely to improve [17]. That was an unvalidated online questionnaire, so treat the number as a signal rather than proof.

A sample low-FODMAP day

  • Breakfast: oats made with lactose-free milk, strawberries and a spoon of peanut butter.
  • Lunch: rice bowl with grilled chicken or firm tofu, carrots, cucumber and spinach, dressed with olive oil and lemon.
  • Snack: a kiwifruit and a small handful of walnuts.
  • Dinner: baked salmon, a jacket potato and green beans with garlic-infused oil.

How long should you follow it?

Follow the elimination phase for two to six weeks. If symptoms improve, reintroduce one FODMAP group at a time and keep every food you tolerate. If nothing has improved by the end of the elimination phase, this diet is probably not your answer. Go back to your clinician rather than cutting more foods.

There are two reasons not to stay on it indefinitely. A 2022 review warns that long-term low-FODMAP eating may shift gut bacteria in an unfavourable direction and deepen the dysbiosis seen in SIBO [11]. And most low-FODMAP trials never studied the reintroduction phase, so the long-term picture is still unclear [7].

Diet during and after treatment

Antibiotics come first for most people. A meta-analysis of 32 studies with 1,331 patients found that rifaximin cleared SIBO in about 71% of cases, with side effects in under 5% [5]. In a non-randomised comparison, an herbal antimicrobial regimen performed similarly, clearing 46% against 34% for rifaximin [16]. The Brazilian Federation of Gastroenterology’s 2025 position paper describes probiotics and dietary changes, particularly low-FODMAP, as ways to complement antibiotic therapy [15].

Fibre may help the antibiotic work. In the only randomised trial of its kind, adding 5 g a day of partially hydrolysed guar gum to rifaximin raised eradication from 62% to about 85% [10]. This is one trial of 77 patients, so it needs repeating.

The elemental diet is an alternative, not a shortcut. It is an option to discuss when antibiotics are unsuitable. Two weeks of formula only is demanding, palatability is the main barrier to finishing it, and it should be supervised [3] [4].

Afterwards, rebuild variety. SIBO often returns, and the position paper stresses long-term follow-up [15]. Preventing relapse depends on the underlying cause, for example prokinetics when gut movement is slow. Permanent food restriction is not the answer. Reintroduce fibre you tolerate and, if they suit you, fermented foods.

When diet is not the right first step

  • See a doctor promptly for weight loss, anaemia, blood in the stool, fever, or diarrhoea that wakes you at night. These need investigation, not a diet.
  • Check your nutrients. SIBO can cause vitamin B12 deficiency and other nutritional deficiencies [2].
  • Elemental diets replace all food for two weeks. Do this only with medical supervision, especially if you have diabetes or another medical condition, are pregnant, or are underweight.
  • A history of an eating disorder makes elimination diets risky. Work with a specialist team before restricting what you eat.

If your clinician suggests a fibre add-on

The only randomised SIBO trial of a fibre supplement used partially hydrolysed guar gum (PHGG), 5 g a day, alongside rifaximin [10].

Partially hydrolysed guar gum on iHerb ↗

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Frequently Asked Questions

What is the best diet for SIBO?

No diet has been proven to cure SIBO. For symptom relief, a short low-FODMAP elimination phase followed by structured reintroduction has the most evidence, mostly from IBS trials. An exclusive elemental diet has the strongest effect on breath tests but must be medically supervised.

Can diet alone get rid of SIBO?

Occasionally, but it is not reliable. In a 2025 trial, a low-FODMAP diet cleared SIBO in half of the SIBO-positive IBS patients, against about two-thirds with rifaximin. Most people need treatment of the overgrowth and of its underlying cause.

How long should I follow a SIBO diet?

Two to six weeks of elimination, then reintroduce foods one group at a time. Long-term restriction may harm beneficial gut bacteria, so the goal is the widest diet you can tolerate.

Should I take probiotics if I have SIBO?

Probiotics improved breath-test clearance in a meta-analysis, but the studies are of low quality and results vary by strain. Treat them as an add-on to discuss with your clinician, not a replacement for treatment.

What should I eat after SIBO treatment?

Reintroduce foods gradually and aim for a varied diet with the fibre you tolerate. Relapse is common, so treating the underlying cause matters more than permanent restriction.

Sources

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  3. Pimentel M, Constantino T, Kong Y, et al. A 14-day elemental diet is highly effective in normalizing the lactulose breath test. Dig Dis Sci. 2004;49(1):73-77. PubMed · DOI
  4. Rezaie A, Chang BW, de Freitas Germano J, et al. Effect, Tolerability, and Safety of Exclusive Palatable Elemental Diet in Patients With Intestinal Microbial Overgrowth. Clin Gastroenterol Hepatol. 2025;23(12):2306-2317.e7. PubMed · DOI
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  10. Furnari M, Parodi A, Gemignani L, et al. Clinical trial: the combination of rifaximin with partially hydrolysed guar gum is more effective than rifaximin alone in eradicating small intestinal bacterial overgrowth. Aliment Pharmacol Ther. 2010;32(8):1000-1006. PubMed · DOI
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