The Low FODMAPs Diet and Prebiotics: Complementary Solutions to IBS?

Functional gastrointestinal disorders (FGDs), such as irritable bowel syndrome (IBS), affect more than 40% of the worldwide population and account for 12% of all primary care appointments (Fikree and Byrne., 2021). FGDs are characterised by chronic, recurring gastrointestinal symptoms, such as abdominal pain, diarrhoea, constipation, bloating and flatulence, and as such can have negative implications for, not only physical wellbeing, but also mental and social wellbeing (Fikree and Byrne., 2021). Whilst there are no underlying structural abnormalities that explain why FGDs occur, the cause of these conditions is thought to be related to gastrointestinal motility, visceral hypersensitivity and altered central nervous system function (Fikree and Byrne., 2021). However, as knowledge surrounding the gut microbiota and its role in health increases, the delicate microbial community residing in the gut have been suggested to also play a role in the pathophysiology of FGDs, as well as potentially being a therapeutic target in the management of these conditions (Wei et al., 2021).

The role of the gut microbiome and the gut-brain axis

The gut microbiome has been shown to have far-reaching benefits for health (Lau et al., 2021). However, when the optimal balance of microbes is disrupted, in what is referred to as dysbiosis, this can contribute to the development of disease, including those of a functional nature such as FGDs (Lau et al., 2021). Studies have shown that those with FGDs, such as IBS, tend to have dysbiosis and lower levels of beneficial bacteria, such as bifidobacteria when compared to healthy individuals (Selvaraj et al., 2020), highlighting a possible role of the gut microbiota in the pathogenesis and potential management of these conditions.

Furthermore, it is important to highlight where the microbiota-gut-brain connection fits into this picture. This network, also called the gut-brain axis, refers to the two-way communication between the brain and the trillions of microbes housed in the gut that is centred upon endocrine, neural and neuroimmune pathways (Tang et al., 2021). The gut-brain axis not only influences mood and cognition, but also influences many gastrointestinal processes including motility and transit, permeability and mucus secretion (Asadi et al., 2022). As a result of its far-reaching capabilities, any disruption to this communication network can contribute to the dysfunction of these processes and the subsequent development of FGDs (Bercik., 2020). Some disruptors of the gut-brain axis and gut microbial composition include modifiable lifestyle factors such as diet, stress, sleep and physical activity, and as such, are often targeted in the management of FGDs.

Dietary solutions and the Low FODMAPs Diet

When looking at the role of dietary patterns in FGDs, Western dietary patterns with a high proportion of refined and processed foods have been shown to increase the risk of developing FGDs and exacerbating symptoms (Dale et al., 2023). Dietary management strategies include the Mediterranean, gluten-free and low FODMAPs diet. The low FODMAPs diet (LFD), in particular, is recommended as a key dietary therapy by national guidelines (Rej et al., 2021) and is one that advises minimising the consumption of indigestible and often fermentable carbohydrates such as lactose, fructose, fructans and sugar alcohols, due to their potential to increase intestinal osmolarity, motility and gas production which can exacerbate symptoms of FGDs (van Lanen et al., 2021).

Whilst clinical trials have proven the effectiveness of the low FODMAP diet in managing FGDs, it is a diet that is restrictive in nature that can have repercussions socially, psychologically and nutritionally, particularly with long-term adherence. Due to the restriction of dietary carbohydrates, often individuals fail to reach their daily fibre requirements which can have implications for the functioning of the gastrointestinal tract. Importantly, fibre is a key dietary component that has been shown to modulate the composition, diversity and richness of the gut microbiota, acting as a food source for beneficial bacteria to support a more favourable balance of microbes (Cronin et al., 2021).

Therefore, questions are being raised as to whether positive modulation of the gut microbiota could complement the use of a low FODMAPs diet and support its efficacy in managing FGDs.

Use of Biotics in the management of FGDs

Biotics, such as probiotics, prebiotics and synbiotics, are fast becoming known as an effective way to support gut health and help to maintain a favourable microbial composition. Whilst similar in the effect they have on the gut microbiota, they are some key differences in what they are and how they work:

  • Probiotics are live micro-organisms, such as bacteria, that aim to colonise in the large intestine and offer health benefits to the host.
  • Prebiotics are indigestible carbohydrates, usually fibres, that when ingested act as a food source for commensal gut microbes.
  • Synbiotics are a combination of a probiotic and a prebiotic that have been tested together to confer a health benefit. These can work independently or together, referred to as complementary or synergistic.

Research suggests that using biotics to modulate the gut microbiota could be an effective way to manage symptoms of FGDs and potentially act as a complementary therapeutic alongside other management strategies, such as the LFD. A recent study by Wilson and co (2023) saw patients diagnosed with IBS as per the Rome III criteria given 1.8g Bimuno GOS daily for 4 weeks whilst simultaneously following a LFD. The results indicated that 67% of participants experienced symptom relief, compared to 50% following a LFD alone and 30% in the control group (Wilson et al., 2023). Furthermore, the addition of Bimuno resulted in a higher number of responders to treatment (Wilson et al., 2023), suggesting that modulation of the gut microbiota with biotics could provide an additional benefit when following an LFD for the management of FGDs.


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