Long-term effects of low-FODMAP diet on IBS yet to be proven: Iranian review

By Cheryl Tay

- Last updated on GMT

More research on the long-term impact of the diet and IBS are needed. ©iStock
More research on the long-term impact of the diet and IBS are needed. ©iStock
A low-FODMAP diet (LFD) can control symptoms of irritable bowel syndrome (IBS), but only in the short term, according to researchers in Iran.

An estimated 10.9% of the Iranian population suffers from IBS, and the condition is more prevalent among women than it is among men.

Apart from the physical discomfort and general inconvenience IBS causes, it also leads to a heavy economic burden on patients and healthcare systems, as well as compromised work productivity.

While medication, psychological therapy, gluten and lactose elimination, and higher probiotic intake have been recommended to manage IBS, experts have also suggested the use of low dietary fermentable short-chain carbohydrates, such as fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAPs).

Common sources of FODMAPs include wheat, beans, rye, fruits and vegetables.

Does it last?

There has been limited research on how FODMAPs can affect IBS symptoms, with some saying a LFD led to a lower frequency of IBS symptoms and others saying the effects are merely short-term.

Researchers at the Tehran University of Medical Sciences and Isfahan University of Medical Sciences therefore conducted a study to collate the findings from previous evidence in order to systematically review how an LFD affected IBS.

They reviewed 15 interventional studies conducted between 2009 and 2016, involving IBS patients aged 11 to 74, who had been recommended an LFD or randomised to receive it.

The sample sizes ranged from 12 to 182 subjects — of which over 70% of the participants were women — and intervention duration was as short as two days and as long as 16 months.

Of these studies, nine were parallel randomised clinical trials, three were randomised crossover trials, and three were of a quasi-experimental design. Nine were conducted in Europe, three in Australia, two in the US, and one in Asia.

The researchers subsequently reported that eight of the studies showed that an LFD significantly improved all IBS symptoms, while one showed an improvement in all systems except constipation.

Another paper stated that an LFD had improved three-quarters of the diarrhoea cases the study had assessed.

On the contrary

However, another study could not find a significant difference between the effects of an LFD and lactobacillusGG​ on IBS symptoms, while yet another observed no notable effect of an LFD on IBS in comparison to the traditional diet recommended for IBS.

The researchers concluded that “adherence to an LFD was not associated with the severity of symptoms”​, and added that while consumption of an LFD might reduce symptoms of IBS, more studies are “required to shed light on inconsistencies in this field”​.

“The previous studies have demonstrated the efficacy of (the) short-term use of LFD in controlling IBS symptoms; however, further data regarding the long-term effects of the diet are needed.”


Source: International Journal of Preventive Medicine


“Consumption of a Low Fermentable Oligo-, Di-, Mono-saccharides, and Polyols Diet and Irritable Bowel Syndrome: A Systematic Review”

Authors: Helia Pourmand, Ahmad Esmaillzadeh

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