Onions and IBS go hand in hand as onions are a high fodmap and a common trigger food for symptoms of IBS such as:
- Abdominal pain and diarrhea
When someone has irritable bowel syndrome or digestive issues, one of the questions I always ask is, how do you tolerate high fodmap foods such as onion and garlic? Most people with IBS and SIBO notice a worsening of IBS symptoms after eating onions or garlic, even in small amounts.
If someone has an onion intolerance, I am always suspicious of SIBO, an overgrowth of bacteria in the small intestine. Avoiding garlic and onions forever is not the answer and is highly challenging as these foods are used to flavor so many savory dishes.
In the short term, avoiding high fodmap trigger foods such as garlic and onion is beneficial. Finding onion substitutes, such as the tops of green onions, is a much-needed crux for many people. But I always try to dig deeper to find out what may be an underlying root cause of SIBO, such as a sluggish gallbladder and low bile flow.
Diarrhea, intolerance to fatty foods, and onion always have me thinking about a sluggish gallbladder contributing to SIBO and, thus, IBS symptoms.
Specific foods such as onion and garlic are almost always IBS triggers as they are high in fermentable oligosaccharides. These short-chain carbohydrates are rapidly fermentable and problematic when fermented by bacteria in the small intestine.
When I worked at a health food store, people frequently came in with digestive symptoms such as bloating, abdominal pain, and burping. Onions and garlic were among the top triggers when I asked if they noticed any triggers for their IBS symptoms.
Following a low fodmap diet free of onion and garlic is only part of the solution. Optimizing digestive health and taking antimicrobials for SIBO were necessary to improve and resolve SIBO symptoms.
Are onions low fodmap?
According to Monash University, both onions and garlic are high fodmap. Still, onion substitutes can flavor your food, such as green onion powder or large onions pickled in vinegar, although you have to be mindful of portion sizes.
Red onion, white onion, shallots, and raw onions are all high fodmap. The tops of green onions are low fodmap in a 75-gram serving or 1.5 cups per meal. Cooking with green onions is a great onion substitute and a way to flavor savory foods.
The bulb of spring onions is high in the fodmap fructose and contains moderate amounts of fructans in a 75-gram serving (1 cup). Be sure only to use the green tops of green onions if you are intolerant to onions.
Gourmend foods have a low-fodmap green onion powder that can be used to season dishes to make low-fodmap foods more flavourful. One serving is ¼ tsp, so use it in small amounts only.
A serving of red onion (3/4 onion) is high in the fructan fodmap, and white onion is high in fructans and moderate amounts of GOS.
One shallot in a 6-gram serve is high in fructans.
Large pickled onions are low fodmap in 45-gram serving size and should be tolerated well by people with IBS. Anyone with a severe onion intolerance, even in small amounts, is better off avoiding onion until a full SIBO protocol has been implemented and you are in the reintroduction phase.
Is garlic high fodmap?
Garlic cloves are right up there with onions as the top IBS triggers, especially for people intolerant to the fructan fodmaps. One clove of garlic (3 grams) is high fodmap.
Garlic powder is also high fodmap even in small amounts, as a serving size of 1 tsp or 2 grams is high in fructans.
Instead, you can try cooking with garlic shoots, as six tablespoons have been tested to be low fodmap. But watch portion sizes as ½ a cup contains moderate amounts of fodmaps, and 1 cup is high in the fodmaps fructose and fructans.
For a garlic substitute, you can also season with garlic scape powder. Garlic-infused olive oil is another excellent way to flavor foods when cooking low fodmap meals.
Understanding the connection between garlic, onions and IBS
The consumption of garlic and onion is a common trigger for IBS symptoms due to the high fructan content in these vegetables. The fructan fodmaps are rapidly fermentable and especially problematic for people with SIBO and IBS.
Individuals with food intolerances to onion often are intolerant to garlic as they both contain fructan fodmaps. Most people with IBS experience a worsening of IBS symptoms within 3 hours after eating high fodmap foods that they are intolerant to.
Bloating, gas and abdominal pain are common symptoms that IBS patients experience after eating onion or garlic, but IBS symptoms are diverse. People can also experience diarrhea, constipation, and alternating diarrhea and constipation! How confusing are those symptoms? Bowel movements can vary drastically for anyone with IBS.
There are different types of fodmaps, but anyone intolerant to fructans will likely notice onions and garlic as common IBS trigger foods. Wheat is also high in fructans and is another common trigger for IBS and SIBO symptoms. People can also experience varying degrees of stomach pain and painful gas as the build-up of excess gas causes pressure.
Crucial questions you need to ask when you have IBS
The big question I always ask when someone has gut health problems is how do you tolerate onions, garlic, and wheat? Do you notice a worsening of digestive symptoms? What are your IBS and SIBO symptoms?
It’s also crucial to ask are onions and garlic the problem or just the trigger. Is the underlying problem due to an overgrowth of bacteria in the small intestine that is feasting on fructan fodmaps in onions?
Those are some fundamental questions to ask yourself as many individuals don’t know that small intestinal bacterial overgrowth is the reason why they have become intolerant to high fodmap vegetables such as onion and garlic. While these foods are high fodmap, they are also highly nutritious vegetables that are not allowed on the low fodmap diet.
I will leave you with another crucial question. Did you know that an underlying root cause of SIBO and IBS is poor bile flow from a sluggish gallbladder? Many SIBO practitioners are missing the root cause of IBS and SIBO, and as a result, people relapse after taking antimicrobials for SIBO.