Onion and garlic are in nearly every standard soup and broth base, and they’re also two of the most concentrated fructan sources in an ordinary kitchen. Get those out of the pot and the rest of the plan holds up well. Leave them in, and you may spend three days making your own symptoms worse while believing you’re doing something gentle for your gut.
A disclosure before we go further: I develop soup cleanse products, which is a reason to read the evidence sections closely rather than take my word for it. Where the research is thin, I’ve said so.
Get the diagnosis right first
IBS is a diagnosis of exclusion, which means a doctor has ruled out other explanations before landing on it. If you haven’t had that evaluation and you’re dealing with abdominal pain, bloating, or irregular bowel habits, see a doctor before trying any dietary experiment, cleanse included. Blood in the stool, unexplained weight loss, fever, anemia, symptoms that wake you at night, a first onset after age 50, or a family history of colon cancer, celiac disease, or inflammatory bowel disease all warrant medical evaluation rather than a soup plan.
If you already have a confirmed diagnosis, the rest of this applies to you directly.
The real risk is the recipe, not the format
A liquid diet for three days isn’t inherently risky for IBS. What’s risky is loading that liquid diet with fructans, and onion and garlic are two of the most concentrated fructan sources in an ordinary kitchen. Fructans are a type of FODMAP, a fermentable carbohydrate the small intestine can’t fully absorb. When they reach the colon, gut bacteria ferment them, and in someone with IBS, that fermentation produces the gas, bloating, and cramping that define the condition.
Every standard soup and bone broth base includes onion and garlic. That’s the single most consequential ingredient swap for anyone with IBS attempting a cleanse.
The fix is straightforward. Fructans dissolve in water but not in oil, so garlic-infused and onion-infused oil carry the flavor without the trigger. Cook the whole clove or chopped onion in oil, then remove the solids before using the oil in your broth. A few commercial infused oils are certified low FODMAP if you’d rather buy one. Fresh ginger, turmeric, and most other herbs aren’t FODMAP concerns and can carry the rest of the flavor.
Vegetable portions worth watching
Most of the vegetables in a typical soup cleanse shopping list are fine in ordinary amounts. Carrot has no meaningful FODMAP ceiling and can be used freely. Zucchini, kale, and spinach are the same. Two vegetables need a closer look.
Sweet potato contains mannitol, a FODMAP that climbs with portion size. Roughly half a cup is the low-FODMAP range; go much beyond that in one serving, and you’re into moderate to high territory. Celery contains mannitol too, in smaller absolute amounts, but it adds up faster than people expect if you’re using several stalks per pot rather than one. Neither vegetable needs to come out of the pot entirely. Both need portioning rather than free use.
If you want exact current thresholds, the Monash University FODMAP app is the primary reference and gets updated as new foods are tested. General food-blog charts on this vary more than they should, and a cleanse isn’t worth building around a number that can’t be sourced back to Monash directly.
Vegetable broth or bone broth
Vegetable broth, blended so it keeps its fibre, is the default and a complete option on its own. It carries no meat, no gelatin, and no animal protein, and none of that matters for FODMAP purposes, since protein and fat don’t carry FODMAPs at all.
Bone broth isn’t required for this, and it doesn’t work any better than vegetable broth does. Made correctly, with no onion or garlic in the pot, it’s inherently low in FODMAPs, since bones, water, and salt essentially contain none. That can make it a simpler starting point for someone newly avoiding trigger ingredients, purely because there’s less to think about. It isn’t a sign that bone broth does more for the gut than vegetable broth does. For the fuller comparison, see Bone Broth vs. Vegetable Broth.
What this cleanse is not
This isn’t a version of the low-FODMAP diet, and shouldn’t be mistaken for one. The actual low-FODMAP protocol is a structured elimination followed by a careful reintroduction, usually run with a dietitian, and it has real trial evidence behind it. A 2024 randomized trial in the Lancet Gastroenterology and Hepatology found that a low-FODMAP diet combined with standard dietary advice brought meaningful symptom relief to 76% of participants after four weeks, with 68% still improved at six months.
A three-day soup cleanse with the trigger ingredients removed borrows the same logic for a much shorter window. It hasn’t been tested in a trial, and it doesn’t treat anything. What it plausibly does is give you three days without your usual fructan exposure, which for some people is enough to notice a difference and decide whether a longer, properly structured elimination is worth pursuing with a dietitian afterward.
How fiber withdrawal cuts both ways
If your IBS runs toward constipation, be aware that abruptly dropping your usual fiber intake for three days can make things worse rather than better, even with a blended, fiber-retaining soup. Soluble fiber is the kind with real evidence behind it for IBS, and going without your normal intake and then expecting improvement isn’t how that evidence works. If constipation is your main issue, keep the soups blended rather than strained, and don’t treat this cleanse as a fiber-reduction strategy.
If your IBS runs toward diarrhea, a low-residue liquid diet for a short stretch often does feel easier day to day, independent of anything specific to soup. That relief comes from volume and residue rather than any specific property of broth, and it won’t outlast the three days unless the trigger foods stay out afterward too.
Running it
Keep it to three days. This isn’t the population to extend a cleanse for.
Remove onion and garlic; replace with infused oil and other aromatics. This is the one non-negotiable substitution.
Portion sweet potato and celery rather than cutting them, unless you already know from experience that they bother you.
Watch for worsening symptoms. If cramping or pain gets worse rather than settling, that’s a stop signal, separate from ordinary hunger. End the cleanse and eat a normal meal instead of pushing through it.
If hunger becomes severe, stop the three days entirely rather than adding solid food partway through. A soup cleanse that quietly includes a soft-cooked egg on day two isn’t a completed three-day cleanse, and pretending otherwise defeats the point of doing it deliberately. The full reasoning behind that line is in the 3-day guide.
Skip this entirely if you haven’t had a confirmed IBS diagnosis. The standard exclusions apply too, pregnancy or breastfeeding, diabetes or medication that requires food, kidney or liver disease, being underweight, or a history of disordered eating; see the full list in the 3-day guide.
Common questions
- Do I need bone broth if I have IBS?
- No. Vegetable broth, blended so it keeps its fibre, is a complete option on its own. Bone broth isn’t required and isn’t more effective; made without onion or garlic, it’s simply low in FODMAPs by default, which can make it a simpler starting point.
- Is a soup cleanse the same as the low-FODMAP diet?
- No. The low-FODMAP diet is a structured elimination and reintroduction, usually run with a dietitian, with real trial evidence behind it. A three-day soup cleanse with onion and garlic removed borrows the same logic for a much shorter window, but it hasn’t been tested in a trial and shouldn’t be mistaken for the real protocol.
- What if I don’t have a confirmed IBS diagnosis?
- See a doctor before trying any dietary experiment, cleanse included. IBS is a diagnosis of exclusion, and symptoms like blood in the stool, unexplained weight loss, or a first onset after age 50 warrant medical evaluation rather than a soup plan.
Two ingredients make the difference
As a category, a soup cleanse isn’t unsafe for IBS. Written the standard way, with the standard recipe, it can be, because that recipe leans on two of the most reliable trigger ingredients that exist. Take those out, watch two vegetables that most people never think twice about, and the three days become a reasonable, low-risk experiment rather than a plan that quietly works against you.