A low-FODMAP diet is a common short-term restrictive diet that’s used to manage IBS symptoms. Although there are benefits to this dietary pattern, there are several potential drawbacks, which can have their own health implications.
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Digestive discomfort can be frustrating, debilitating, and, at times, embarrassing. For many people with conditions like irritable bowel syndrome (IBS), a low FODMAP diet has become the go-to strategy for managing symptoms like bloating, gas, and abdominal pain. For 70% of people, it works, but it is only a temporary solution [1].
Although a low FODMAP diet can offer some much-needed relief, it’s not without its downsides. For example, it can cause more harm than good if it is followed for too long, too strictly, or without proper physician supervision [2]. It can be particularly harmful to your gut microbiota due to the diet's restrictive nature.
Here, we discuss some of the lesser-known drawbacks of a low FODMAP diet and what you can do to support your gut health more sustainably.
What is a low FODMAP diet?
A low-FODMAP diet is an elimination diet developed by researchers at Monash University in 2005 [3]. It is a three-step, evidence-based dietary approach to managing IBS that involves restricting, then reintroducing, specific fermentable carbohydrates.
FODMAPS are:
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Fermentable – carbohydrates that are fermented by gut bacteria, which produce gases
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Oligosaccharides – soluble fibers known as probiotics, such as fructans and galacto-oligosaccharides, and include foods such as onions, beans, lentils, garlic, and wheat
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Disaccharides – lactose, a sugar found in milk and dairy products
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Monosaccharides – the fermentable sugar in this group is fructose, the sugar found in fruit and honey
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Polyols – also known as sugar alcohols (sorbitol and mannitol), which are commonly used in artificial sweeteners and can be found naturally in some fruits and vegetables
These carbohydrates are poorly absorbed in the small intestine and rapidly fermented by gut bacteria, leading to gas production and digestive symptoms in some sensitive individuals. By restricting and then reintroducing these foods, you can identify your IBS triggers and follow a diet pattern that keeps your symptoms in check.
Phases of the low-FODMAP diet
There are three distinct phases of the low-FODMAP diet: restriction, reintroduction, and personalization [4].
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Restriction |
Swap high FODMAP foods for low FODMAP alternatives |
2 to 6 weeks |
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Reintroduction |
If symptoms improve in phase 1, start reintroducing FODMAPs by introducing 1 food daily and record responses |
8 to 12 weeks |
|
Personalization |
You should now be able to identify which foods you can tolerate and which trigger symptoms to help you build a personalized diet plan |
Long-term diet |
The potential drawbacks of a low-FODMAP diet
Clinical trials have demonstrated that a low-FODMAP diet can have great benefits for IBS sufferers. For example, one study found that 90% of IBS and diarrhoea (IBS-D), 75% of IBS and constipation (IBS-C), and 84% of mixed IBS patients respond well to a low-FODMAP diet and report an overall improvement in their symptoms [5].
However, despite its benefits, there are some potential long-term consequences of following a low-FODMAP diet, including the risk of nutritional deficiencies and a low-diversity gut microbiome.
1. Your gut microbiome can be negatively impacted
Many FODMAPs are not just problem foods; they’re also prebiotics, which means they feed beneficial gut bacteria. So, when you restrict them, you risk starving the microbes that support your gut health.
Research shows that a low-FODMAP diet lowers your total gut bacterial count and gas production [6]. The diet also reduced Bifidobacteria levels, one of the most common and beneficial genera present in the gut [7], which have a key role in:
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supporting digestion
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maintaining the gut lining
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regulating the immune system
At the same time, reducing fermentable and prebiotic fibers can lower the production of short-chain fatty acids (SCFAs) like butyrate. These are compounds that can help nourish the cells lining the colon and reduce inflammation. Over time, this can lead to a less diverse and less resilient gut microbiome.
2. Increased risk of nutritional deficiencies
Although the restrictive phase of the low-FODMAP diet is short-lasting, nutritional deficiencies can occur and potentially worsen gastrointestinal symptoms. Some of the many nutrient-rich foods that may be restricted as part of a low-FODMAP diet, include:
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fruit
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vegetables
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beans, legumes, and wholegrains
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dairy products
Long-term restriction of these foods can lead to lower intakes of important nutrients such as:
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fiber
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calcium
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B vitamins
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vitamin D
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vitamin C
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antioxidants and polyphenols
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zinc
Catassi and colleagues suggested that the risk of nutritional deficiencies on a low-FODMAP diet may be higher among people with lower socio-economic status. That’s because they may have limited access to many of the expensive and alternative foods, supplements, and dietary items that may be included in a low-FODMAP diet [8].
3. Highly restrictive and difficult to follow
Following a low-FODMAP diet is not as simple as just cutting out one ingredient; it requires a multi-faceted approach that involves:
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reading food labels carefully for their ingredients
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understanding portion sizes and portion control
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awareness of hidden FODMAPs
This complexity can make everyday eating more stressful, especially when travelling, eating out, or socializing.
Some examples of high and low FODMAP foods are:
One study found that adherence to a low-FODMAP diet ranged from 10% in patients with IBS-C to 51% in patients with IBS-D [9]. Over time, this level of restriction can reduce your enjoyment of food and make the diet difficult to adhere to.
4. May affect your relationship with food
Mari et al., (2019) found that greater adherence to a low-FODMAP diet was linked with disordered eating behaviours [10], which is something everyone needs to be aware of, especially those with a history of eating disorders.
The low-FODMAP diet can significantly impact your relationship with food, resulting in anxiety, fear of eating, and social restriction because of the diet's restrictive nature. This is one of the reasons why a low-FODMAP diet is not recommended long-term because it can turn eating into a stressful and mental burden.
5. Low-FODMAP diet is not a cure for IBS
The low-FODMAP diet is not a cure. Instead, it offers a way to manage IBS symptoms. It helps you to identify the potential triggers for your gastrointestinal symptoms and eliminate them completely from your diet.
However, if FODMAPs are not an underlying contributory factor to your IBS symptoms, it is unlikely that a low-FODMAP diet will be beneficial.
Alternative therapeutic approaches in IBS
While dietary strategies like the low FODMAP diet can be helpful, they are not the only option for managing the debilitating symptoms of IBS. Increasingly, research is focusing on therapies that directly target the gut microbiome, such as probiotics and prebiotics, emerging as alternatives or complementary approaches.
Probiotics: Can “good bacteria” restore balance?
Probiotics are live microorganisms that, when consumed in sufficient quantities, can provide health benefits, particularly by helping restore balance in the gut microbiome. Research has shown that probiotics are safe and effective in IBS patients, especially when used for less than 8 weeks [11].
One review found that a multi-strain probiotic had greater potential to improve IBS symptoms than a single-strain probiotic [12].
A 2024 meta-analysis involving more than 3,000 people found that probiotics were more effective than a placebo in improving global IBS symptoms and quality of life. The same research suggested that supplements containing multiple probiotic strains or high doses were preferable for symptom management [13].
Prebiotics: Feeding your microbiome
Prebiotics, on the other hand, are non-digestible compounds that selectively nourish beneficial gut microbes, offering a powerful way to work with your microbiota to promote diversity. You may be thinking that prebiotics can worsen IBS symptoms, especially those sensitive to FODMAPs. That’s true, particularly in the case of more traditional prebiotic types.
However, newer approaches, such as human milk oligosaccharides (HMOs), may differ. One 2020 study by Iribarren et al. found that a 4:1 mix of 2’fucosyllactose (2’-FL) and Lacto-N-neotetraose (LNnT) increases faecal Bifidobacteria levels without aggravating IBS symptoms in 4 weeks. A 10g daily dose had the greatest influence on overall faecal microbiota composition [14].
A 12-week study by Palsson and colleagues found that a 5g daily 4:1 mix of 2’-FL and LNnT improved IBS symptoms and quality of life without any substantial side effects [15].
Overall, HMOs could offer a more selective and gentle way to nourish your gut microbiome by increasing beneficial species and supporting a healthier gut microbiota profile. They are also well tolerated with fewer side effects.
▶ Want to try HMOs to manage your IBS symptoms? Order our PureHMO® IBS Support with IBS Defend Probiotic, a combination of 2’-FL and LNnT and Lactobacillus acidophilus, a probiotic strain developed for IBS relief.
Summary
Managing IBS often involves a trial-and-error approach and may require more than 1 strategy to achieve long-term symptom improvement. Although restrictive diets like low-FODMAP can help in the short term, they don’t always support your long-term nutrition and gut health.
By reintroducing foods, prioritising diversity, and supporting your gut microbiome with targeted solutions such as HMOs, you can move beyond restriction towards lasting digestive health.
Author details
Written by: Leanne Edermaniger, M.Sc. Leanne is a professional science writer who specializes in human health and enjoys writing about all things related to the gut microbiome. She has written extensively on inflammatory bowel disease, prebiotics, and microbiome research.
Her work focuses on translating complex medical science into evidence-based, practical health guidance.
