Prebiotics vs. low-FODMAP Diet

Posted on Mon, 3 Sep 18

Prebiotic supplements have been shown to reduce digestive symptoms, but so has the low-FODMAP diet, which restricts prebiotics. To solve this contradiction a study compared the two strategies directly. 

The low-FODMAP diet limits consumption of fermentable fibres and has been used to help reduce digestive symptoms such as flatulence, bloating, pain, constipation/ and or diarrhoea. Although it can be helpful, the diet is also restrictive and results in changes in gut bacteria that may have adverse effects in the long-term. 

In contrast, a seemingly conflicting approach is also helpful; increasing intake of fermentable fibres with prebiotics. Prebiotics have demonstrated similar benefits to a low-FODMAP diet but improve gut bacteria. 

Specifically, the low-FODMAP diet reduces Bifidobacteria, a key species of the microbiome, while prebiotics increase their abundance. 

To directly contrast the effects of these different nutritional therapies, a randomized, parallel, double-blind study of patients with functional gastrointestinal disorders with flatulence was performed. The interventions were either 1) prebiotic supplement (1.37g of beta- galactooligasaccharide) and a Mediterranean-type diet, or 2) a placebo supplement plus a low-FODMAP diet. 

After 4 weeks there were opposite effects on gut bacteria, with an increase in Bifidobacteria abundance in the group taking prebiotics while the low-FODMAP diet decreased Bifidobacteria. Further, Bilophila wadsworthia decreased in the prebiotic group and increased in the low-FODMAP group. 

Symptom reduction, including abdominal bloating, distension and abdominal discomfort and pain, was significant and similar in both groups. Reductions in flatulence and borborygmi were not significant in the prebiotic group, but when treatment values minus pretreatment values were compared there was no difference between the two interventions. 

Interestingly, people in the low-FODMAP diet were more likely to have a symptom relapse when tested again 2-weeks after the 4-week study, although symptom relapse was still lower than pretreatment.

“From a practical perspective, our study indicated that, in the short run, daily administration of beta-galactooligasaccharide prebiotic was equally effective as an low-FODMAP diet,” commented the study investigators. ‘ 

"Since dietary restrictions, particularly the low-FODMAP diet, are cumbersome to follow, these results present an alternative patient management strategy. Furthermore, given the sustained effect of beta-galactooligasaccharide compared to the reversible effects of low FODMAP diet, intermittent treatment with beta-galactooligasaccharide might represent an additional advantage over the continuous treatment required with low-FODMAP diet,” they said. 

Reference: 

Huaman JW, Mego M, Manichanh C, et al. Effects of Prebiotics vs a Diet Low in Fodmaps in Patients with Functional Gut Disorder. Gastroenterology. 2018 Jun 28. pii: S0016-5085(18)34687-0. doi: 10.1053/j.gastro.2018.06.045. [Epub ahead of print]